regional variation of spring n uptake and new production in the southern ocean 1 nitrate ammonium and urea uptake were examined in the southern ocean australian sector during the 2001 austral spring on the basis of n uptake conditions three regions were distinguished 1 the sub antarctic zone and the sub antarctic front 2 the polar and inter polar frontal zones and 3 the antarctic zone south and the seasonal ice zone n uptake was highest in region 3 and dominated by new production region 1 had the lowest n uptake and switched from regenerated to new production between two visits approximately 1 month apart region 2 displayed intermediate n uptake and the lowest new production this contrasts with previous study at 170 w where new production was high around the polar front and indicates that this area is not highly productive nor particle exporting at all longitudes overall n uptake and new production were low all along the latitudinal transect compared to other areas of the southern ocean under spring conditions

evidence for interaction of a spreading ridge with the outer california borderland abstract the southward passage of the rivera triple junction and its effect on the north american plate are primary controls on the miocene tectonic evolution of the outer borderland of california detrital modes of sand shed off the patton ridge and cored by the deep sea drilling project provide evidence of progressive tectonic erosion of the patton accretionary prism and near trench volcanism volcanic glass in the sediment is predominantly calcalkaline rhyolite and andesite typical of subduction related volcanism but also includes minor low k2o tholeiitic basalt we attribute these compositional features to interaction with a spreading ridge associated with a possible trench ridge trench triple junction along the patton escarpment from 18 to 16 ma this study suggests that evidence of ridge trench interaction may be commonly preserved along submerged plate margins in contrast to its more limited recognition and discussion in the literature based on exposed examples in chile japan and alaska

sedimentology and reservoir potential of matilija sandstone an eocene sand rich deep sea fan and shallow marine complex california the matilija sandstone of the santa ynez mountains of southern california records a major regressive event in the eocene santa ynez basin in which turbidites were deposited and subsequently covered by shallow marine deposits despite thick favorable source beds and generally good initial reservoir characteristics the matilija sandstone is not a productive unit in the basin low reservoir permeability generally less than 1 md and porosity 1 to 10 are interpreted to be the result of early compaction cementation and diagenesis the lower part of the matilija sandstone is a 1 300 ft 400 m thick sand rich deep sea fan complex which overlies basin plain turbidite deposits of the juncal formation the matilija sandstone consists of anastomosing outer fan lobes lobe fringe and interlobe deposits overlain by channelized middle and inner fan deposits the upper matilija sandstone consists of shallow marine cross bedded sandstone red beds and carbonate evaporite lignite sequences which overlie the turbidites deposition of the matilija sandstone was terminated by a rapid basin deepening event which culminated in deposition of basin plain slope and turbidite deposits of the cozy dell formation the lower matilija sandstone deep sea fan deposits have a high sandstone to shale ratio 4 1 to 10 1 and consist of submature arkoses folk 1980 the depositional lobes consist of facies b c and d turbidites and a channelized sequence of facies a and b turbidites the average sandstone is medium grained moderately sorted subangular to subrounded and massive containing 40 quartz 35 feldspar about equal amounts of plagioclase and potassium feldspars 10 lithic fragments mostly volcanic and metamorphic types and minor amounts of detrital clay illite mica chert and heavy minerals early compaction carbonate cementation and authigenic pore lining and pore filling chlorite albite potassium feldspar quartz and localized laumontite have reduced the initial porosit and permeability the only remaining porosity is secondary resulting from the dissolution of detrital feldspars and minor fracture porosity

lithofacies analysis of the dezadeash formation jura cretaceous yukon canada the depositional architecture of a mud sand rich turbidite system abstract the dezadeash formation is a northwest trending belt of predominantly jura cretaceous deep marine siliciclastic rocks in southwestern yukon canada it is truncated to the southwest by the denali fault system a major transcurrent fault along which 370 km of dextral slip occurred in post early cretaceous time and it is flanked to the northeast by the kluane schist a mainly mica quartz schist assemblage of unknown age and origin this study provides a robust quantitative description of lithofacies comprising a point source mud sand rich turbidite system approximately 16 335 m of measured strata from 75 sections throughout the dezadeash formation indicate that up to 29 lithofacies types are present and these are dominated by thin to thick bedded sandstone mudstone couplets and medium to thick bedded sandstone the various lithofacies are grouped into conglomerate sandstone sandstone mudstone and siltstone mudstone lithofacies associations which are interpreted as slide channel lobe transition lobe and overbank architectural elements respectively stacked channel lobe transition and lobe elements predominate but the depositional architecture displays no apparent overall vertical trend the dezadeash formation represents mainly the lower middle and lower subdivisions of a point source mud sand rich turbidite system that records a single stage of fan growth as it prograded transversely from a volcano plutonic arc into the basin

cyclic stacking pattern architecture and facies of the turbidite lobes in the macigno sandstones formation chattian aquitanian northern apennines italy abstract this study presents a detailed facies analysis of an 800 m thick stratigraphic succession in the basinal turbidites of the macigno sandstones formation msf recording the first foredeep in the northern apennines italy this stratigraphic succession shows an evident stacking pattern that besides the basal part 200 m thick dominated by fine grained and thin beds is characterized by seven magnificently exposed sandstone lobes from 90 to 19 m thick separated by well developed fine grained interlobe deposits thanks to the detailed facies analysis not only a well defined architectural hierarchy has been identified but a facies scheme has also been proposed whereby cyclic recurring of three facies associations has in turn been identified each facies association records a well determined evolutionary stage of lobe development where an early depositional stage of the lobe building phase is followed by a flow impact and bypass stage recording flow decelerations and hydraulic jumps induced by the morphology created by the underlying depositional lobe the latter phase promotes a switching and channel feeder avulsion that heralds the third phase of abandonment with the deposition of fine grained interlobes the facies stacking pattern and the evolutionary model of the msf also supported by other similar field and experimental works are intended as a contribution to the understanding of intrinsic autogenic mechanisms at the basis of sand rich depositional lobe development

re examining the antarctic paradox speculation on the southern ocean as a nutrient limited system the southern ocean is the largest of the high nutrient low chlorophyll hnlc regions of the world ocean phytoplankton production fails to utilise completely the pool of inorganic nutrients in the euphotic zone giving rise to low phytoplankton biomass and leaving relatively high summer nutrient concentrations this enigma is of considerable significance for our understanding of the role of the oceans in the global carbon cycle various limiting factors have been considered low light low temperature absence of necessary trace elements grazing pressure and other means of biomass removal the dynamics of nitrogen uptake by phytoplankton are of particular importance classically nitrate mixed into the surface layer during winter provides the nitrogen pool for growth in the spring bloom some organic material is exported to depth whilst the remainder is recycled providing ammonium and other reduced species as nitrogenous substrates for growth during the remainder of the season the oxidation state of the inorganic nitrogen supply thus identifies new and recycled carbon fixation whilst this is convenient shorthand for the nitrogen nutrition of carbon export in much of the ocean it is an inappropriate model for the southern ocean here nitrate and ammonium use are simultaneous and nitrate is never exhausted by the annual phytoplankton production we speculate that a range of environmental factors combine to make the large pool of nitrate partially inaccessible to phytoplankton in addition to the documented effects of low iron availability and high ammonium concentrations the low temperatures characteristic of the southern ocean may decrease nitrate availability because of the increased energetic overheads in its uptake and reduction this in turn makes ammonium an important nitrogenous substrate and its production by zooplankton and heterotrophic microorganisms is an important component of the plankton nitrogen cycle there is some evidence that ammonium production by large grazing animals may stimulate phytoplankton growth microbial removal of nitrogen from sedimenting phytoplankton cells may result in local decoupling between the carbon and nitrogen cycles allowing some reduced nitrogen to remain in the euphotic zone whilst carbon is exported to depth

sensitivity of δ15n of nitrate surface suspended and deep sinking particulate nitrogen to seasonal nitrate depletion in the southern ocean 1 we report measurements of the 15n of nitrate suspended particulate nitrogen pn and sinking pn from cruises and moored sediment traps in the subantarctic zone saz and polar frontal zone pfz south of australia as expected surface water nitrate 15n increased as nitrate was consumed during the spring summer bloom in contrast the seasonal cycles of surface water suspended and sinking pn 15n did not fit expectations from nitrate assimilation alone rather than increasing the 15n of surface suspended pn was relatively constant in the saz at 1 and decreased during the summer in the pfz from 0 to 4 most likely due to the production of low 15n pn by summertime ammonium recycling deep sediment trap pn 15n also displayed seasonal decreases from 4 to 1 in the saz and from 3 5 to 0 5 in the pfz which correlated with pon flux magnitude during high flux periods exported pn 15n values were close to expectations from nitrate based export but low flux periods exhibited higher 15n consistent with either a reduction in the isotope effect of nitrate assimilation or more extensive isotopic alteration of the sinking material during low flux periods the mass balance between net nitrate supply and exported pn that links sinking flux 15n to nitrate utilization requires only that the annually integrated rather than the seasonally varying sinking flux of pn 15n correlates with nitrate depletion while a correlation between annually integrated sinking pn 15n to nitrate depletion was observed in both the saz and pfz the sensitivity of sinking pn 15n to nitrate depletion was lower than expected moreover the seasonal observations raise the possibility that loss of the summertime high flux period represents an alternative explanation to increased nitrate utilization for the high sedimentary pn 15n observed during glacial periods

slope and deep sea fan facies and paleogeography of upper cretaceous chatsworth formation simi hills california the upper cretaceous chatsworth formation is a sand rich deep sea fan deposit consisting of thick channelized sequences and interchannel deposits typical of middle fan facies it has poorly developed outer fan lobes and slope facies petrographic and x ray diffraction xrd data indicate the arkosic deposits of the chatsworth formation were derived from an uplifted granitic terrane paleocurrent studies indicate northward sediment transport and an east trending slope regional comparisons of the simi hills with the santa monica and santa ana mountains suggest these terranes were once contiguous and covered part of a deep sea fan system that comprised much of the southern california area subsequently these terranes have been offset along the malibu cucamonga and elsinore faults and rotated in response to the opening of the los angeles basin and to other adjustments in the tectonic framework of the area the chatsworth formation is thought to be part of a forearc basin deposit similar to the great valley sequence and not part of the salinian borderland block the original geographic position of the forearc basin was to the south of the sierra nevada mountains and the great valley sequence

forecasting of scatterometer derived wind fields in the north indian ocean with a data adaptive approach 1 a combination of genetic algorithm ga and empirical orthogonal function eof analysis has been employed to forecast satellite scatterometer observed surface winds in the north indian ocean the eofs are used to compress the major part of the spatial variability into a few eigenmodes the temporal variability is contained in the corresponding principal components pc which have been subjected to singular spectrum analysis for filtering out the random part forecast of the deterministic part has been carried out using ga with lead times varying from 1 to 4 days the entire analysis has been done separately for the zonal and meridional winds finally predicted wind fields have been generated as linear combinations of the spatial eigenmodes weighted by the predicted pcs forecast quality has been evaluated by comparing with an independent validation data set as well as with buoy data the performance of the algorithm has been found to be quite encouraging

moored sediment trap measurements of carbon export in the subantarctic and polar frontal zones of the southern ocean south of australia sediment trap moorings were deployed from september 21 1997 through february 21 1998 at three locations south of australia along 140 e at 47 s in the central subantarctic zone saz with traps at 1060 2050 and 3850 m depth at 51 s in the subantarctic front with one trap at 3080 m and at 54 s in the polar frontal zone pfz with traps at 830 and 1580 m particle fluxes were high at all the sites 18 32 g m 2 yr 1 total mass and 0 5 1 4 g organic carbon m 2 yr 1 at 1000 m assuming minimal flux outside the sampled summer period these values are similar to other southern ocean results and to the median estimated for the global ocean by lampitt and antia 1997 and emphasize that the southern ocean exports considerable carbon to the deep sea despite its high nutrient low chlorophyll characteristics the saz site was dominated by carbonate 50 of total mass and the pfz site by biogenic silica 50 of total mass both sites exhibited high export in spring and late summer with an intervening low flux period in december for the 153 day collection period particulate organic carbon export was somewhat higher in all the traps in the saz range 0 57 0 84 gc m 2 than in the pfz range 0 31 0 53 with an intermediate value observed at the saf 0 60 the fraction of surface organic carbon export estimated from seasonal nutrient depletion lourey and trull 2001 reaching 1000 m was indistinguishable in the saz and pfz despite different algal communities

quantifying the hierarchical organization of compensation in submarine fans using surface statistics abstract stratigraphy is often interpreted within hierarchical or scale dependent frameworks that subdivide deposits based on distinct jumps in characteristics such as duration of deposition or scale while the interpretation is logically valid few studies quantitatively demonstrate that the jumps exist rather recent work has quantitatively shown some characteristics of stratigraphy to be fractal or scale invariant compensational stacking the tendency for sediment transport systems to preferentially fill topographic lows is a concept widely used in stratigraphic interpretation here we use the compensation index a metric that quantifies the strength of compensational stacking in sedimentary deposits to describe the architecture of stratigraphy exposed in outcrops of submarine fan strata in the carboniferous ross sandstone representing contrasting architectural styles 1 predominantly lobe elements and 2 predominantly channel elements in both datasets the stratigraphic architecture is classified into hierarchical classes of beds stories and elements results are the following first at both sites we document statistically significant increases in the strength of compensation across larger hierarchical levels supporting the use of hierarchical interpretations of stratigraphy it is therefore plausible for some characteristics of sedimentary systems to be hierarchical and others to be fractal second we document that lobe elements stack more compensationally than channel elements we interpret this pattern to document that compensation increases along a longitudinal transect through this distributive submarine fan

high frequency cyclicity milankovitch and millennial scale in slope apron carbonates zechstein upper permian north east england the upper permian zechstein slope carbonates in the roker formation zechstein 2nd cycle carbonate in north east england consist of turbidites interbedded with laminated lime mudstone studies of turbidite bed thickness and relative proportion of turbidites percentage turbidites in 20 cm of section reveal well developed cyclicities consisting of thinning upward and thickening upward packages of turbidite beds these packages are on four scales from less than a metre up to 50 m in thickness assuming that the laminae of the hemipelagic background sediment are annual allows the durations of the cycles to be estimated in addition counting the number and thickness of turbidite beds in 20 cm of laminated lime mudstone which is approximately equivalent to 1000 years each lamina is 200 m gives the frequencies of the turbidite beds the average thicknesses and the overall sedimentation rates through the succession for 1000 year time slots figures obtained are comparable with modern rates of deposition on carbonate slopes the cyclicity present in the roker formation can be shown to include milankovitch band ca 100 kyr short eccentricity ca 20 kyr precession and ca 10 kyr semi precession cycles and sub milankovitch millennial scale cycles 0 7 to 4 3 kyr eccentricity and precession scale cycles are related to highstand shedding and relative sea level change caused by milankovitch band orbital forcing controlling carbonate productivity the millennial scale cycles which are quasi periodic probably are produced by environmental changes controlled by solar forcing i e variations in solar irradiance or volcanic activity most probable here are fluctuations in carbonate productivity related to aridity humidity and or temperature changes precession and millennial scale cycles are defined most strongly in early transgressive and highstand parts of the larger scale short eccentricity cycles the duration of the roker formation as a whole can be estimated from the thickness of the laminated lithotype as ca 0 3 myr

flow bearing structures of fractured rocks insights from hydraulic property scalings revealed by a pumping test abstract a long duration pumping test conducted over 151 days in a fractured sandstone and shale formation displays a nonstandard drawdown response and anomalous pressure diffusion which cannot be properly interpreted using existing frameworks e g homogeneous double porosity boundary conditions and fractal models an alternative framework with simple geometry and more complex hydraulic properties is thus proposed to interpret such kind of drawdown responses the analytical development allows first to demonstrate all scaling relations in this interpretation framework then and most importantly the multi scale hydraulic test provides consistent scalings of transmissivity t to storativity s over distances ranging from 83 to 383 m in a faulted area drawdown analysis in several monitoring wells shows persistent decrease of transmissivity in highly channelized fracture flow structures in one structure the cubic dependency of transmissivity to storativity identifies a well defined fault and also demonstrates the validity of poiseuille flow at a scale rarely investigated in the other structure the linear dependency of transmissivity to storativity indicates that the flow bearing structure is the surrounding fracture network well designed pumping tests combined with scaling analysis driven by geological evidence thus provide essential information on flow bearing structures for site characterization and modeling tasks at least for moderate to low permeable fractured rocks the scaling of transmissivity to storativity appears to be more informative than any separate interpretation of hydraulic property scaling exponents

predicting wind field in the bay of bengal from scatterometer observations using genetic algorithm 1 a technique based on genetic algorithm ga is applied for predicting wind field in the bay of bengal bob using satellite scatterometer observations empirical orthogonal function eof analysis is used for compressing the spatial variability into a set of eigenmodes the time series of each principal component pc is subjected to singular spectrum analysis ssa and ga is applied to the resulting filtered time series the forecast pcs are weighted by the spatial eigenmodes for computing forecast wind fields predictions made up to 5 days in advance are found to be superior to forecast by persistence method

late devonian to early carboniferous turbidite facies and basinal development of the eastern klamath mountains california abstract the late devonian to early carboniferous bragdon formation eastern klamath mountains california is a thick turbidite sequence deposited as a submarine fan complex within an arc related basin laminated mudstone and less abundant classical turbidites comprise most of the lower part of the bragdon and represent a lower fan environment amalgamated beds of normally graded to massive sandstone and pebbly sandstone occur throughout the bragdon but are most abundant in its upper half where they are associated with very thick channel fill beds of pebbly sandstone and conglomerate the upper half of the bragdon formation represents a mid fan to upper fan environment and it also includes closely interbedded classical turbidites interpreted as interchannel or levee deposits an upper slope facies of bioturbated mudstone with an early carboniferous fauna occurs at the top of the formation clastic material in the bragdon formation indicates little contemporaneous vulcanism and was probably derived from lower paleozoic metasediments which were uplifted to the north deposition of the bragdon was initiated by rifting and subsidence of an underlying middle devonian arc complex infilling of the resulting basin during the late devonian and early carboniferous is indicated by overlap of turbidite facies across middle devonian arc deposits and by an upward stratigraphic trend in the bragdon from lower fan to upper fan and slope environments

predicting wave heights in the north indian ocean using genetic algorithm 1 the present work reports the development of a nonlinear technique based on genetic algorithm ga for the prediction of wave heights in the north indian ocean time series observations of surface wind speed and significant wave height at three locations in the arabian sea as and the bay of bengal bob have been used for developing and testing the technique the predictions have been compared with persistence forecasts and it has been found that the prediction by ga is always superior to persistence forecast and thus represents a net information gain the predicted wave heights have been found to be consistent with the results obtained with autocorrelation analysis applied on the respective time series of wave heights

braided and meandering submarine fan channel deposits tesnus formation marathon basin west texas abstract exposures of predominantly mid fan channel deposits from the tesnus formation upper mississippian lower pennsylvanian of west texas provide an opportunity to examine possible meandering and braided deposits in a single submarine fan system within the tesnus six fan related sedimentary facies are recognized i amalgamated sandstone without vertical thickness trends ii amalgamated sandstone with thinning upward trends iii massive matrix rich sandstone iv interbedded sandstone and shale v chaotic sandstone and shale and vi black mudrock and chert the arrangement of sedimentary facies the nature of facies contacts and sandstone geometries differ significantly for braided versus meandering channel deposits sheet like braided channel deposits commonly exhibit a more random facies ordering and abrupt facies transitions whereas pod shaped meandering channel deposits commonly possess a more orderly arrangement of facies from base to top facies i vi in sequential order with gradual facies transitions the aforementioned differences in channel deposit characteristics are believed due primarily to variations in the migrational history of the braided abandonment and rapid shifting versus meandering gradual erosion and migration channel networks

controls on the carbon isotopic composition of southern ocean phytoplankton carbon isotopic compositions of suspended organic matter and biomarker compounds were determined for 59 samples filtered from southern ocean surface waters in january 1994 along two north south transects woce sr3 from tasmania to antarctica and across the princess elizabeth trough pet east of prydz bay antarctica along the sr3 line bulk organic matter show generally decreasing 13c contents southward which are well correlated with increasing dissolved molecular carbon dioxide concentrations co2 aq this relationship does not hold along the pet transect using concentrations and isotopic compositions of molecular compounds we evaluate the relative roles of several factors affecting the 13c of southern ocean suspended particulate organic matter along the woce sr3 transect the concentration of co2 aq plays an important role it is well described by a supply versus demand model for the extent of cellular co2 utilization and its associated linear dependence of isotopic fractionation ep on the reciprocal of co2 aq an equally important factor appears to be changes in algal assemblages along the sr3 transect with their contribution to isotopic fractionation also well described by the supply and demand model when formulated to include the cell surface volume control of supply changes in microalgal growth rates appear to have a minor effect on ep along the pet transect algal assemblage changes and possibly changes in microalgal growth rates appear to strongly affect the carbon isotopic variations of suspended organic matter these results can be used to improve the formulation of modern carbon cycle models that include phytoplankton carbon isotopic fractionation

structural and statistical characterization of joints and multi scale faults in an alternating sandstone and shale turbidite sequence at the santa susana field laboratory implications for their effects on groundwater flow and contaminant transport abstract this paper describes the properties of faults and fractures in the upper cretaceous chatsworth formation exposed at santa susana field laboratory and its surroundings simi hills california where groundwater flow and contamination have been studied for over three decades the complex depositional architecture of this turbidite consisting of alternating sandstones and shales interacting with formative stress conditions are responsible for multi scale fault hierarchies and permeable fractures in which nearly all groundwater flow occurs intensity and distribution of background fractures and their relation to bedding thickness are established for sandstones the dominant lithology the architecture of faults with increasing displacement is described and relationships among fault dimensional parameters captured data from 400 boreholes and piezometers reveal the effect of faults and fractures on groundwater flow large hydraulic head differences observed across fault zones with shale rich cores indicate these structures as cross flow barriers moreover hydraulic head profiles under ambient conditions and pumping tests suggest strong hydraulic connectivity in all directions to depth of hundreds of meters this outcrop based structural characterization relates the horizontal hydraulic conductivity to the observed well connected fracture network and explains the strong vertical connectivity across low hydraulic conductivity shales as faults and sheared fractures provide flow pathways

compaction corrected paleomagnetic paleolatitudes for late cretaceous rudists along the cretaceous california margin evidence for less than 1500 km of post late cretaceous offset for baja british columbia the paleolatitudinal distribution of bivalve rudists has important significance for the baja british columbia baja bc hypothesis that western canadian superterranes from british columbia have been displaced 3000 km since cretaceous time rudists are not observed in baja bc sedimentary rocks yet they are common in late cretaceous strata in california and baja california which have the same paleomagnetically determined paleolatitudes approximately 25 n as baja bc rocks of late cretaceous age in order to resolve this contradiction and to delimit more exactly the southern paleolatitudes of baja bc paleomagnetic inclinations corrected for the effects of burial compaction were used to determine the paleolatitudinal distribution of rudists along the california margin compaction corrected paleomagnetic data from the peninsular ranges and salinia terranes indicate that rudists were restricted to paleolatitudes between 34 and 40 n evidence of coastal upwelling in the latest cretaceous marca shale may explain the northern limit of the rudist distribution these data suggest that baja bc was no farther south than 40 n in the late cretaceous thus limiting its post cretaceous displacement to less than 1500 km and that burial compaction has also affected the paleomagnetism of nanaimo group sedimentary rocks from vancouver island this result also helps resolve the conflict between paleomagnetic results which show 1500 km of post late cretaceous offset between the insular coast plutonic complex superterrane and the intermontane superterrane and geologic observations which can allow only tens of kilometers of offset between these terranes in the methow tyaughton basin

sedimentation in deep sea lobe elements implications for the origin of thickening upward sequences the frequency and origin of thickening upward packages in the sediments of deep sea environments has been a topic of much recent debate excellent bed scale exposures in the carboniferous ross formation western ireland allow single surfaces to be traced laterally and the detailed architecture of whole packages to be evaluated using multiple vertical logs the deposits comprise architectural elements including bed sets lobe elements and composite lobes with the lobe elements being arranged in thickening upward depositional packages results show that these packages are the result of the progradation of each lobe element whereby each package records a vertical trend from distal to proximal deposits accompanied by an increasing frequency of megaflutes and ultimately the development of broad erosional surfaces we propose a six stage model for lobe element evolution that documents successive phases of deposition sediment bypass erosion and lobe abandonment this new model provides a mechanism for lobe element switching and explains the development of thickening upward successions this allows the re examination of existing process models for these sedimentary packages in deep sea sediments

anatomy of collapsed and re established delta front in lower cretaceous of eastern spitsbergen gravitational sliding and sedimentation processes spectacular coastal cliff exposures in an early cretaceous deltaic succession near kvalvagen in eastern spitsbergen norwegian arctic show a variety of styles of gravity driven deformation and resedimentation associated with delta front progradation and instability the large scale collapse involved a distributary channel sand unit some 20 m thick and the underlying delta slope prodelta shaly heterolithics the deformation was essentially brittle whereby large blocks of the delta front succession slid and rotated its gross style involved two large cuspate tear away scars at least 1 1 5 km wide and 50 60 m deep separated by narrow remnant buttresses of in situ strata the basement in the region was tectonically active and the delta front failure was most likely sei mically triggered initial infill of the collapse scars involved slumps and debris flows derived from scar walls and locally from the sliding blocks themselves these deposits partly smoothed the local topography created by the slide blocks this early infill was followed by deposition of thin mainly muddy turbidites probably shed from the scar walls by small localized failure renewal of fluvial supply of sand led to the main infill of the scar depressions this stage involved effluent generated turbidites heterolithic and increasingly sandier turbidites and liquefied sandflows derived from unstable oversteepened distributary mouthbars the mouth bar systems eventually achieved stability and prograded across the infilled scars they were affected by periodic storm wave attack and sudden increa es of water depth the scar infill at that stage was subject to minor growth faulting possibly related to new seismic tremors

a statistical test for significance of thinning and thickening upwards cycles in turbidites abstract in turbidite successions asymmetric cycles identified in vertical sections are often used as indicators of sedimentary processes in submarine fan models thickening and coarsening upwards cycles are thought to characterize depositional lobes whereas thinning and fining upwards cycles are believed to be produced by filling and abandonment of channels a non parametric statistical test based on the signs of differences between consecutive bed thickness values may be used to determine whether the cycles in a particular measured section are statistically significant the test can be modified to deal with bed thickness values that have been smoothed by moving averages and with multiple partial sections in an incompletely exposed unit

the puncoviscana trough a large basin of late precambrian to early cambrian age on the pacific edge of the brazilian shield during the late precambrian to early cambrian a large basin with a homogeneous psammitic pelitic sediment fill existed in the area of the nw argentine andes it is now exposed in different tectonic levels this basin of meridional elongation was situated on a stable continental margin at the western edge of the brazilian shield it was underlain by segmented older continental crust according to the modal and chemical composition of the greywackes and subgreywackes a predominant metasedimentary source may be supposed four clastic facies types indicate a transport by gravity currents within a submarine fan system while massive red pelites represent cut off periods and rare carbonates deposition on rises the gravity currents derived from easterly directions the sedimentation age is proved by a rich ichnofauna and some medusoid impressions

biogeochemical iron budgets of the southern ocean south of australia decoupling of iron and nutrient cycles in the subantarctic zone by the summertime supply 1 climate change is projected to significantly alter the delivery stratification boundary currents aridification of landmasses glacial melt of iron to the southern ocean we report the most comprehensive suite of biogeochemical iron budgets to date for three contrasting sites in subantarctic and polar frontal waters south of australia distinct regional environments were responsible for differences in the mode and strength of iron supply mechanisms with higher iron stocks and fluxes observed in surface northern subantarctic waters where atmospheric iron fluxes were greater subsurface waters southeast of tasmania were also enriched with particulate iron manganese and aluminum indicative of a strong advective source from shelf sediments subantarctic phytoplankton blooms are thus driven by both seasonal iron supply from southward advection of subtropical waters and by wind blown dust deposition resulting in a strong decoupling of iron and nutrient cycles we discuss the broader global significance our iron budgets for other ocean regions sensitive to climate driven changes in iron supply

limitation of algal growth by iron deficiency in the australian subantarctic region in march 1998 we measured iron in the upper water column and conducted iron and nutrient enrichment bottle incubation experiments in the open ocean subantarctic region southwest of tasmania australia in the subtropical convergence zone 42 s 142 e silicic acid concentrations were low 1 5 m in the upper water column whereas pronounced vertical gradients in dissolved iron concentration 0 12 0 84 nm were observed presumably reflecting the interleaving of subtropical and subantarctic waters and mineral aerosol input results of a bottle incubation experiment performed at this location indicate that phytoplankton growth rates were limited by iron deficiency within the iron poor layer of the euphotic zone in the subantarctic water mass 46 8 s 142 e low concentrations of dissolved iron 0 05 0 11 nm and silicic acid 1 m were measured throughout the upper water column and our experimental results indicate that algal growth was limited by iron deficiency these observations suggest that availability of dissolved iron is a primary factor limiting phytoplankton growth over much of the subantarctic southern ocean in the late summer and autumn

quartzose turbidites of the accretionary complex of barbados ii variations in bedding styles facies and sequences abstract barbados provides the only subaerial exposures of the barbados ridge an accretionary complex lying outboard of the lesser antilles volcanic arc within nine measured sections of quartzose turbidites five major types of sequences are recognized 1 1 progradational sequences basin plain outer fan of uniformly fine grained flat based base absent turbidites that thicken upward and gradually become coarser grained and base present at the top of the sequence 2 2 a single rejuvenation rapid progradational sequence was identified as an abrupt progradational sequence above abandoned lobe deposits and is not characterized by stacked well developed upward thickening successions as many progradational sequences are 3 3 channelized successions of coarse grained base present turbidites arranged in packets 5 20 or 50 140 m thick which are midfan and inner fan deposits respectively the distinction between predominance of base present and base absent turbidites seems to correspond with the interpreted change from midfan channelized to outer fan sheet flow deposition 4 4 one example of a major retrogradational sequence of midfan deposits above inner fan sandstones has been found on barbados minor sequences of facies retrogradation are relatively common in the outer fan environment where upward thinning sandstone beds overlie upward thickening units to define symmetric sequences 5 5 abandonment successions are major as indicated by massive accumulations of mudstone minor as indicated by abrupt reversals of upward thickening trends in outer fan lobe deposits and cryptic where indicated by thick 4 m bioturbated zones of massive sandstone

statistical appraisal of bed thickness patterns in turbidite successions andaman flysch group andaman islands india abstract the bed thickness distribution of two turbidite successions in the oligocene andaman flysch group india which differ in terms of their paleogeography and sediment supply has been assessed statistically the purpose was to evaluate depositional cyclicity using the non parametric waldron test and also to assess possible environmental control on the bed thickness magnitude distribution both sections reveal a positively skewed distribution in bed thickness patterns the z value obtained through waldron s test failed to reject the null hypothesis of randomness and thus discards a cyclic pattern juxtaposition of sediments of different proximalities in an elongated forearc fan complex is the possible cause for this absence of cyclicity the studied sections however differ in their bed thickness magnitude distribution slope turbidite successions with sediment supply solely from the outer arc reveals a scaling behavior while the outer fan succession with mixing of sediments from different sources show a negative exponential distribution this highlights the possible control of the depositional system and sediment supply on the bed thickness magnitude distribution of turbidite successions irrespective of the triggering mechanism unequivocal application of the power law distribution in turbidite successions demands reconsideration

sedimentation of deep water slope base and inner fan deposits the drosgol formation ashgill west central wales abstract the sedimentology of the drosgol formation is summarised in terms of nine sedimentary facies with particular attention given to the pebbly mudstones and major arenites sedimentary facies geometry and palaeocurrents suggest the interpretation of the major arenites as inner fan channel deposits locally preserving their levees the lower less organised part of the formation suggests a slope base environment with small scale channelling slumping and development of mass flow deposits a new definition of the upper boundary of the formation is proposed and map references are given to key localities

intraseasonal periodicities in indian rainfall abstract spectral analysis of a 70 year 1901 70 record of daily precipitation from 3700 stations in the country of india is carried out to search for periodicities on subseasonal time scales during the summer monsoon two statistically significant spectral peaks are found a 40 50 day spectral peak corresponding to the madden julian oscillation is found over most of the portion of india south of 23 n the phase of the oscillation is such that the precipitation maximum appears first over the relatively dry southeastern portion of the peninsula ten to 12 days later the precipitation peaks simultaneously all along the coast west of the western ghats and along a line running across india between 20 and 25 n the precipitation maximum then spreads slowly northward and loses significance cross spectral analysis shows strong coherence between the precipitation patterns and wind oscillations the zonal wind oscillations at 850 and 200 mb am about 180 degrees out of phase equatorward of about 20 n but in pha

relationship of nitrogen isotope fractionation to phytoplankton size and iron availability during the southern ocean iron release experiment soiree the 15 n composition of sediments has been used as a proxy for nitrate utilization in surface waters to assess the role of southern ocean export production in glacial interglacial changes in atmospheric co 2 concentration interpretation has relied on a temporally constant isotope effect associated with uptake and assimilation of nitrate by phytoplankton to investigate the reliability of this approach we examined the relationships between the 15 n compositions of dissolved nitrate bulk and size fractionated 200 70 20 5 1 mm suspended particulate organic nitrogen pon and sinking particles obtained from sediment traps during the southern ocean iron release experiment soiree we found variations in phytoplankton nitrogen isotopic compositions with both cell size and iron availability d 15

late quaternary depositional systems and sea level change santa monica and san pedro basins california continental borderland a suite of seismic reflection data that provides different degrees of resolution and penetration was used to map the depositional systems that have developed in santa monica and san pedro basins during the late quaternary submarine fan growth particularly at the mouths of hueneme and redondo canyons has been the dominant mode of basin filling mass movement processes ranging from creep to large scale catastrophic slumping have been important locally in general large scale fan growth fits normark s model in which the suprafan is the primary locus of coarse sediment deposition smaller scale morphologic and depositional patterns on the hueneme and redondo fans e g distributary channels and coarse sediment concentrations basinward of the inner suprafan suggest that a significant amount of coarse sediment presently bypasses the suprafans however long distance coarse sediment transport was particularly pronounced during late wisconsinan lowstand of sea level and resulted in progradation of lower mid fan and lower fan deposits as sea level rose rapidly between 18 000 y b p and 10 000 y b p shelves trapped much of the sediment supply consequently rates of basin sedimentation decreased markedly and the area of fan developmen was restricted as the rate of shelf sedimentation decreased concomitantly with a decrease in the rate of sea level rise 10 000 y b p sediment transport to the basins was renewed and modern depositional patterns were established fan development also has been influenced by large scale mass movement extensive mid fan overbank flow and the consequent development of sediment waves deflection of turbidity currents by bathymetric obstacles and local tectonism correlations between sand layer characteristics and high resolution echo types for fan and basin plain deposits show trends similar to some of those observed in deep sea depositional environments however because santa monica and san pedro basins are small enclosed tectonically active basins that receive sediment from relatively large drainage areas proximal to distal changes in sand layer thickness abundance and frequency are less pronounced than those observed in deep sea environments

the age of water and ventilation timescales in a global ocean model abstract the age of water in the world ocean is studied using a passive age tracer introduced into a global ocean model additional information is derived from a transient dye tracer that tracks the time dependent spreading of surface waters into the model ocean interior of particular interest is the nature of ocean ventilation over the 10 100 yr timescale as well as the simulated age of deep and bottom water masses in the upper model levels young water is found to correspond with regions of convergence and downwelling in the surface ekman layer upwelling and convection are both shown to age the upper ocean by entraining older waters into the surface mixed layer in the deep model levels water age varies greatly between oceans with young water found in convectively active regions in the north atlantic and in the ross and weddell seas and old water found in the deep north pacific the oldest water mass mixture located at 2228 m depth in the western pacific ocean is dated at 1494 years made

turbidites in foreland and on thrust basins of the northern apennines abstract turbiditic sediments are associated with all stages of development of the apennines orogen not only the classical flysch of oligo miocene age macigno cervarola marnoso arenacea but also the coeval smaller bodies based on thrust sheets loiano of ranzano sequence and the younger molasse of the plio pleistocene foredeep except for more recent ones quaternary turbidite units are affected to some degree by thrusting and later block faulting the equivalent marginal deposits were also deformed uplifted and eroded to a great extent however identification and correlation of sequences and paleoenvironments across the orogenic belt can be helped by a deposits with rather strong eustatic imprint high stands and b preservation of marginal sediments by early remobilization cannibalism into deeper depocentres the following categories of basins can be recognized main foreland basin or foredeep in front of thrust sheets based on undeformed or previously rifted continental crust thrust top basins meso autochthonous auct in absence of a well defined major foredeep satellite basins thrust based but inwardly associated with a foredeep and of much smaller size linear dimensions in the order of kilometers and ten of kilometers volume of fill in the order of tens to hundreds cubic kilometers the foredeep persisted for the whole orogenic cycle but changed its character and was more or less segmented two main stages can be recognized conventionally labelled as the flysch stage up to the late miocene appenines mostly submerged and the molasse stage late miocene to recent present relief already in existence satellite basins floating on the ligurian sheet epi ligurian persisted up to the mid pliocene but received turbidites only in the oligocene and miocene others were created later on thrusts of different style involving the foreland sedimentary cover piggyback basins of ori and friend 1984 turbidite lithosomes of the flysch group are the largest ones volumes up to 30 000 km 3 with maximum size and lateral continuity of individual beds megaturbidites they are not seen as overlapping units filling coexisting and adjacent basins but as distinct superposed isochronous units within which only time transgressive sedimentation could occur macigno thus stands for all oligocene turbidites of the northern apennines foredeep cervarola for early miocene ones and marnoso arenacea for mid late miocene ones it is assumed that these units reflect sedimentary cycles of some order correlatable with global charts and splittable into depositional sequences sensu vail and collaborators

the shochary ridge sequence southeastern pennsylvania a possible ordovician piggyback basin fill abstract the central appalachian orogen of eastern pennsylvania is underlain in part by three fault bounded deep water clastic sequences the windsor township formation of the hamburg klippe greenwich slice the martinsburg formation and the shochary ridge sequence deep water sandstones of the windsor township formation were deposited in a trench on oceanic lithosphere in early middle ordovician time clastic detritus of the late middle early late ordovician martinsburg formation accumulated as part of a longitudinal deep sea clastic system in the central appalachian foreland basin deposits of the coeval shochary ridge sequence comprise a 1500 m thick coarsening upward sequence of hemipelagic mudstone and siltstone turbidites although devoid of the type of bedding cyclicity implicit to published submarine fan models the shochary ridge sequence may have accumulated as part of a morphologically poorly developed deep sea fan in which submarine channels and depositional lobes never formed or were poorly developed at best the coarsening upward nature of the shochary ridge sequence probably reflects progradation of its depositional system in response to either an inferred late middle early late ordovician glacially induced reduction in sea level and or an increase in tectonic activity in the hinterland sedimentologic and paleocurrent data suggest that deposits of the shochary ridge sequence did not accumulate as part of the martinsburg depositional system palinspastic restoration places the shochary ridge depocenter to the southeast of the martinsburg basin i e on the orogen side of the foreland basin accordingly the shochary ridge sequence is interpreted to reflect gradual filling of a basin that existed within the active thrust terrane to the southeast of the martinsburg depocenter this basin a piggyback or slope basin formed on martinsburg strata that had been tectonically incorporated into the northwest migrating thrust terrane as the frontal thrust advanced into the foreland basin

storm deposited sandstones tempestites and related ichnofossils of the late ordovician georgian bay formation southern ontario canada the late ordovician geogian bay formation of southern ontario canada comprises up to 250 m of grey to blue grey shales interbedded with highly fossiliferous calcareous sandstones these strata were deposited in equatorial paleolatitudes after 448 ma in a shallow foreland basin created by overthrusting along the eastern margin of north america the taconic orogeny the georgian bay formation comprises the middle part of an upward shallowing progradational sequence from deep water transgressive shales of the underlying whitby formation to muddy tidal flat sequences of the overlying queenston formation exposures in brickyard and river cuts near toronto and northwards along a narrow outcrop belt along the foot of the niagara escarpment show laterally extensive 100 m sharp based sheets of sandstone up to 1 m thick with gutter casts and washed out hypichnial trace fossils dominantly planolites and paleophycus on their lower bedding surfaces detailed examination of sandstone beds in outcrop and i

types of submarine fan lobes models and implications different lobe models imply significantly different reservoir geometries thus one must apply the proper lobe model to ancient fan sequences braided suprafan lobes are characterized by stacked channel sand bodies with good lateral and vertical communication and they constitute excellent reservoir facies depositional lobes composed of sheet like sand bodies with good lateral and moderate vertical communication exhibit properties of good reservoir facies fanlobes which refer to meandering channels and associated levee facies of large mud rich submarine fans such as the mississippi fan are characterized by offset stacked sand bodies with poor lateral and vertical communication these lenticular sands have the potential to be moderately good reservoir facies ponded obes which represent mud rich slump facies of slope environments comprise poor reservoir facies because of low sand content and poor sand body connectivity furthermore the presence of contorted mud layers in ponded lobes is expected to hinder fluid flow external mounded reflections in seismic profiles often are interpreted as lobes however there are no definite seismic criteria to delineate mud rich lobes from sand rich lobes

an empirical estimate of the southern ocean air sea co2 flux 1 despite improvements in our understanding of the southern ocean air sea flux of co2 discrepancies still exist between a variety of differing ocean atmosphere methodologies here we employ an independent method to estimate the southern ocean air sea flux of co2 that exploits all available surface ocean measurements for dissolved inorganic carbon dic and total alkalinity alk beyond 1986 the dic concentrations were normalized to the year 1995 using coinciding cfc measurements in order to account for the anthropogenic co2 signal we show that independent of season surface normalized dic and alk can be empirically predicted to within 8 mol kg using standard hydrographic properties the predictive equations were used in conjunction with world ocean atlas 2001 climatologies to give a first estimate of the annual cycle of dic and alk in the surface southern ocean these seasonal distributions will be very useful in both validating biogeochemistry in general circulation models and for use in situ biological studies within the southern ocean using optimal co2 dissociation constants we then estimate an annual cycle of pco2 and associated net air sea co2 flux including the effects of sea ice we estimate a southern ocean 50 s co2 sink of 0 4 0 25 pg c yr our analysis also indicates a substantial co2 sink of 1 1 0 6 pg c yr within the sub antarctic zone 40 s 50 s associated with strong cooling and high winds our results imply the southern ocean co2 flux south of 50 s to be very similar to those found by takahashi et al 2002 but on the higher end of a range of atmospheric oceanic co2 inversion methodologies this paper estimates for the first time basic seasonal carbon cycle parameters within the circumpolar southern ocean which have up to now been extremely difficult to measure and sparse the application of such an empirical technique using more widely available hydrographic parameters in the southern ocean provides an important independent estimate to not only co2 uptake but also for other future biogeochemical studies refining and testing these empirical methods with new carbon measurements will be important to further reduce uncertainties and extend our understanding of southern ocean co2 dynamics

shallow water turbidites an example from the mallacoota beds australia abstract a late ordovician turbidite sequence the mallacoota beds exhibits vertical lithofacies associations that suggest deposition in a fan like environment however there are also features indicating occasional episodic reworking by water currents reworking features include both wave current and unidirectional ripple pavements sharp topped turbidites a difference in current direction between superimposed current rippling and underlying bouma c division ripples lensiodal quartzites and occasional hcs beds comparisons between the mallacoota beds and the depositional products of a variety of open ocean currents would indicate that storm related currents were the most likely reworking mechanism this would indicate that the sequence was deposited within storm wave base depositional depths for part of the sequence are estimated at 90 200 m based on a wave generated ripple model therefore these turbidites may have been produced by storm surge with channeling within the turbidites due to the localisation of rip currents during hurricane conditions a generalised model for the characteristic features of turbidites deposited between fair weather wave base and storm wave base is presented it is suggested that such turbidites will contain only occasional examples of reworking and that the frequency of such reworking events per stratigraphic interval might be used as a relative measure of water depth throughout a sequence moreover those turbidite sequences that have sharp contacts between the sandstones and the overlying mudstones may have been modified by storms and therefore deposited in shallower water than previously thought

nitrogen isotopic evidence for a poleward decrease in surface nitrate within the ice age antarctic abstract surface sediment diatom bound 15 n along a latitudinal transect of 170 w shows a previously unobserved increase to the south of the antarctic polar front the southward 15 n increase is best explained by the combination of two changes toward the south a decrease in the isotope effect of nitrate assimilation e and an increase in the degree of nitrate consumption both associated with shoaling of the mixed layer into the seasonal ice zone siz new downcore records show high amplitude changes in diatom bound 15 n during the last ice age with intervals of higher 15 n including the last glacial maximum the transition between marine isotope stages 5 and 4 and marine isotope stage 6 while other intervals are similar in 15 n to interglacial sediments variation in the range of 0 3 as seen in previously published records may be entirely due to changes in e however the observed magnitude of the change of 4 10 in the three new records and the locations of these records relative to the modern meridional gradient in mixed layer depth appear to require increased nitrate consumption to explain the high 15 n intervals the new sites are near the modern southern antarctic circumpolar current front saccf and one of the sites has been shown to be associated with sporadic summer sea ice during the lgm as with other antarctic sites the available proxy data suggest that they were characterized by lower export production based on these and other observations we propose that the weak southward nitrate decrease in the modern antarctic surface was a fully developed nutrient front in the glacial antarctic associated with the saccf both modern ocean and paleoceanographic work is needed to test this hypothesis which would have major implications for atmospheric co 2

mass transfer from the alps to the apennines volumetric constraints in the provenance study of the macigno modino source basin system chattian aquitanian northwestern italy a quantitative provenance approach is applied to the late oligocene early miocene macigno modino turbidite complex which accumulated in the foreland basin developed in front of the growing northern apennines but was supplied from the rapidly rising western alps at the northwestern end of the basin as well as the traditional recognition of source rock lithologies and their gross paleogeographic location the provenance approach adopted here evaluates the relative contributions to the clastic complex from different types of source rock and estimates the volume of material transferred from the alps to the apennines within the macigno modino source basin system and the overall volume of rock assumed to have undergone erosion in order to supply it these elements are used to constrain the possible source of the clastics and to infer the main paleogeological features of the source area it is concluded that an estimated volume of ca 17 20 103 km3 of basement mainly metamorphic rocks together with ca 103 km3 of intermediate composition volcanic rocks was transferred as detritus from the western alps area to the northern apennines foreland basin creating the 250 300 km long 50 km wide and up to 2 7 km thick macigno modino clastic complex lithology and paleogeography combined with volume estimates and current knowledge of the regional geology of the western alps consistently suggest that the bulk of the sediments funnelled into the macigno modino complex were derived from the uplifted ivrea crustal block which formed a crystalline massif some 5000 km2 in extent that rose ca 3 km during the oligocene forming one of the main elements of western alpine geology during that time

paleocene carbonate turbidites of the şarkisla region turkey their significance in an orogenic basin abstract a paleocene carbonate sequence occurs in the southwestern part of the sivas refahiye basin arkisla province sivas turkey and is located in the northeast of central anatolia conclusions concerning the late mesozoic to early cenozoic sedimentary evolution have been derived mainly from the carbonate turbidites the vertical and lateral relationships of these rocks suggest deposition in a submarine fan complex three major megacycles characterized by a thickening and coarsening upward trend are seen in the upper cretaceous lower paleocene succession they are considered to represent basin facies in the lower levels passing upward into sediment attributed to distal fan facies on the basis of bed thickness distributions and bioclastic hemipelagic ratios agglomerates occur as laterally discontinuous mass flow deposits which formed on the slopes of local volcanoes located in the deeper part of the basin thin lava sheets are the products of stratovolcanoes which result from regional tectonic subsidence olistoliths occurring at several stratigraphic levels probably are the result of seismic events related to contemporaneous volcano tectonic activity two major turbiditic megacycles occur also in the middle and upper parts of the succession middle and upper paleocene the lower megacycle of this sequence conforms to the distal division of a suprafan lobe while the upper part is marked by a conspicuous thickening and coarsening upward character indicating a suprafan lobe environment this evidence is consistent with an overall progradation of the fan complex during the paleocene paleocurrent features and slump structures indicate that the marginal slopes of the basin extended in a northeast southwest direction and were inclined to the north sedimentologic stratigraphic tectonic and volcanic data from this sequence suggest that during the paleocene this area formed as an arc related basin

statistical analysis of turbidite bed thickness patterns from the alpine fold and thrust belt of western and southeastern greece abstract a statistical evaluation of turbidite bed thickness was performed for 11 turbidite successions which constitute part of foreland basins formed along the alpine fold and thrust belt of western and southeastern greece the purpose was to compare the results from this study with previously published investigations and discuss if and how statistical approaches could contribute to the environmental analysis of turbidite deposits in tectonically complex areas bed thickness datasets exhibit a clear non normal signal in their distribution behavior statistical analysis was focused on i fitting of widely used non normal theoretical distribution models using robust non parametric goodness of fit statistical tests and ii detecting the possible presence of asymmetric bed thickness cycles and or non random bed thickness clustering results indicate that the studied bed thickness datasets are well characterized by a bimodal lognormal distribution model probably reflecting deposition from both high and low density turbidity currents several datasets exhibit distributions characterized by power law tails exponential distribution types were not observed all datasets exhibit non random thinning upward bed thickness trends probably due to tectonically induced gravity flows proposed methods for identifying depositional sub environments using turbidite bed thickness statistics were found to have limited applicability observations of the present study may prove useful for the environmental analysis of turbidite deposits in fold and thrust belt areas characterized by limited outcrop exposures

sedimentology of a late cenozoic collisional sequence the misis complex adana southern turkey abstract this study is concerned with miocene sequences formed within part of the cukurova basin of southern turkey a major downwarp created during the early stages of collision between the afro arabian plate and the tauride anatolian microplate assemblage we report here the results of a combined stratigraphical sedimentological structure and geochemical study of the misis complex a structurally elevated segment of cukurova basin fill this analysis has demonstrated the structurally imbricated nature of the misis sequences and the tectonic juxtaposition of originally well separated coeval facies the initial discernible phase of basin filling pre burdigalian was marked by deep marine conditions and marginal tectonic instability probably related to a late phase of tauride nappe advance the subsequent phase of crustal extension burdigalian early tortonian produced expansion of the cukurova basin limits and an upwards shoaling succession in which sediment transport towards the southwest gradually became dominant as a result of earlier suturing and uplift in northeasterly sectors of the collision zone the miocene arenites of the misis complex are petrographically diverse with common siliciclastic and carbonate detrital admixtures and mineralogically immature and their position in petrotectonic fields indicates a compound provenance from both recycled orogen and magmatic arc sources a noteworthy petrographic feature is the compositional similarity of arenites from both shallow and deep marine facies the general succession of neogene facies observed in the cukurova basin and misis complex is consistent with their evolution within a perisutural foreland basin but this interpretation is complicated by petrographic and geochemical features attributed to remnants of an older magmatic arc later stages of basin filling are also marked by the local occurrence of anomalous palaeoenvironmental associations including olistostromic units attributed to contemporaneous intra basinal tectonism

deep sea fan deposits in the macigno formation middle upper oligocene of the gordana valley northern apennines italy abstract facies characteristics are described for a 2300 m thick turbidite succession of the macigno formation middle upper oligocene which crops out as a continuously exposed section in the gordana valley northern apennines in the study area the macigno formation consists of two sandy members separated by a shaly member the sandy members contain lithic associations characteristic of submarine fan deposits and form distinct fan complexes the middle shaly member represents a period of basin starvation three main facies associations are recognized in the macigno fan deposits fan fringe outer fan lobe and braided midfan facies associations the fan fringe deposits consist of monotonous or small scale cyclically arranged thin bedded turbidites the outer fan lobe deposits are composed of medium to very thick bedded classical turbidites internally organized in thickening upward cycles with minor intercalations of thin bedded sandstone beds two distinct types of outer fan lobe deposits distal and proximal are recognized on the basis of rock type internal organization and vertical facies relationships the midfan deposits consist of amalgamated massive sandstone and pebbly sandstone which display repeated thinning upward cycles the three main facies associations are superposed t define major thickening and coarsening upward cycles reflecting distinct episodes of fan progradation the relationships between the facies associations of the macigno deposits and the existing models of submarine fan sedimentation are discussed after the deposition of the fan complexes fan sedimentation in this part of the basin was replaced by movements of allochthonous units heralded by large olistostromes

ocean surface wind prediction in the north indian ocean from in situ and satellite observations using genetic algorithm 1 possibility of predicting surface wind speed in the north indian ocean from in situ observations and surface wind components from satellite scatterometer observations using an approach based on genetic algorithm ga has been demonstrated in this work the approach unlike other prediction methods provides explicit analytical forecast equation predictions made up to 3 days in advance have been found to be significantly superior to those made by persistence and autoregressive techniques

geochemistry of suspended particles in the subantarctic and polar frontal zones south of australia constraints on export and advection processes filtered particles from a southern ocean meridional transect from 42 s to 54 s along 142 e off tasmania were studied between surface and 600 m water depth saz 1998 expedition february april 1998 particulate ba sr ca p u th ti al mn light rare earth elements and zr contents were analyzed by inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectroscopy mesopelagic baxs total ba minus a lithogenic fraction estimated from al contents were higher within the polar front zone pfz in comparison with the northern areas indicating that c export to the intermediate and deep ocean is more important in the pfz average surface uxs versus latitude covaries with mesopelagic baxs contrasting with organic matter proxies such as pp and chlorophyll a this similar behavior suggests that u might be preferentially adsorbed on organic material which subsequently becomes involved with barite precipitation srp and cap contents decrease sharply with depth following total particle content for the northern area 42 47 s surface ce anomaly reflects essentially a lithogenic signature 0 6 ce ce 1 ascribed to the supply from the tasmanian continental shelf suspended matter from surface waters at stations south of 47 s shows an enhanced seawater signature 0 3 ce ce 0 6 in all stations ce anomalies increase with depth toward values close to 1 this is likely due to the increase of lithogenic authigenic ratio of particles with depth rather than redox processes finally an advective event is identified at 45 s below 200 m by a strong increase of lithogenic element contents which affects baxs

deep sea coral evidence for lower southern ocean surface nitrate concentrations during the last ice age the southern ocean regulates the ocean s biological sequestration of co 2 and is widely suspected to underpin much of the ice age decline in atmospheric co 2 concentration but the specific changes in the region are debated although more complete drawdown of surface nutrients by phytoplankton during the ice ages is supported by some sediment core based measurements the use of different proxies in different regions has precluded a unified view of southern ocean biogeochemical change here we report measurements of the 15 n 14 n of fossil bound organic matter in the stony deep sea coral desmophyllum dianthus a tool for reconstructing surface ocean nutrient conditions the central robust observation is of higher 15 n 14 n across the southern ocean during the last glacial maximum lgm 18 25 thousand years ago these data suggest a reduced summer surface nitrate concentration in both the antarctic and subantarctic zones during the lgm with little surface nitrate transport between them after the ice age the increase in antarctic surface nitrate occurred through the deglaciation and continued in the holocene the rise in subantarctic surface nitrate appears to have had both early deglacial and late deglacial holocene components preliminarily attributed to the end of subantarctic iron fertilization and increasing nitrate input from the surface antarctic zone respectively

regional circulation and its impact on upper ocean variability south of tasmania ocean colour images of the subantarctic zone saz south of tasmania show a higher biomass in the east than in the west to identify the main features of the regional circulation and the physical drivers of the east west contrast we used world ocean circulation experiment hydrographic sections sr3 and p11s west and east of tasmania respectively argo float profiles and trajectories and high resolution climatology the east australian current and the tasman outflow are the mechanisms driving the variability in the eastern subantarctic zone this region has a weak flow and an enhanced input of subtropical waters through eddies interleaving and a subsurface salinity maximum intruding from the north to south in the western subantarctic zone the regional circulation is dominated by a northwestward circulation and a deep reaching anticyclonic recirculation the south tasman rise acts as a barrier inhibiting exchange between waters southeast and southwest of tasmania the regional circulation and mixing processes result in the strong contrast in water properties between the eastern and western subantarctic zone cooler and fresher in the west and warmer and saltier in the east the subantarctic mode water samw pycnostad is more prominent in the west with a local variety of samw associated with the anticyclonic recirculation west of the south tasman rise antarctic intermediate water aaiw formed in the southeastern pacific and southwestern atlantic oceans meet in the saz south of tasmania cool fresh and well ventilated aaiw is found in the west and southeast saz relatively warm salty and low oxygen aaiw enters the saz from the tasman sea after having traversed the pacific ocean subtropical gyre enhanced input of subtropical water high in micronutrients such as iron in the east likely supports the higher surface biomass observed there the physical processes responsible for maintaining the east west contrast south of tasmania e g regional circulation eddies and intrusions are likely to drive variability in physical and biogeochemical properties of samw aaiw and the subantarctic zone elsewhere in the southern ocean

selective alteration of arkose framework in oligo miocene turbidites of the northern apennines foreland impact on sedimentary provenance analysis

seasonal nutrient depletion and carbon export in the subantarctic and polar frontal zones of the southern ocean south of australia seasonal surface water nitrate and phosphate depletions were calculated for the subantarctic zone saz and polar frontal zone pfz of the southern ocean along the world ocean circulation experiment sr3 repeat section south of tasmania australia and three other transects slightly to the west the depletions were calculated between a single winter july section and eight other sections from october to march in the years 1991 1998 and corrected for frontal movements and changes in water masses between the cruises using observed quasi linear nutrient salinity relationships arranged in a seasonal progression depletion began in approximately october and continued through march in good agreement with satellite biomass based estimates of production nitrate depletion in the saz 510 mmol n m 2 was approximately twice that of the pfz 250 mmol n m 2 but phosphate depletions were similar 29 and 24 mmol p m 2 for the saz and pfz respectively the saz exhibited a redfield n p depletion ratio 15 1 2 3 but the pfz ratio was much lower 8 3 5 4 while the saz exhibits greater seasonal nutrient depletion the relative magnitudes of export in the two zones remain uncertain because supply of nutrients from south of the polar front may lower the observed nutrient depletions in the pfz however comparisons with sediment trap and production measurements for the region south of australia suggest the saz and pfz differences derive from differences in production assuming a redfield c n ratio 6 6 carbon export for the longest period examined july march averaged 3400 430 mmol c m 2 in the saz with a range between 2700 and 3900 mmol c m 2 depending on latitude in the pfz carbon export averaged 1600 350 mmol c m 2 with a range of 1100 to 2000 mmol c m 2 these averages represent minimum annual export production estimates because neither resupply nor export outside the july march observational period is included

structure and transport of the antarctic circumpolar current and agulhas return current at 40 e hydrographic data are presented from a near meridional section across the agulhas return current the subtropical front and the antarctic circumpolar current acc in the southwest indian sector of the southern ocean the location and characteristics of the fronts are examined and the water masses are defined the agulhas return current emerges as a strong current as far east as 40 e which forms a marked front that is separate from the subtropical front and can be distinguished by a separate water mass comparisons are made with a similar hydrographic section at the greenwich meridian and several notable differences are found the subantarctic front at the greenwich meridian is a pronounced feature carrying a large proportion of the geostrophic transport of the acc on the southwest indian section however the subantarctic front is merged with the polar front at 48 s where the flow associated with the acc is concentrated geostrophic calculations show a large volume transport 84 to 103 sverdrup 1 sv 106 m3 s 1 associated with the agulhas return current at 40 s this is quite separate from the transport of the acc which totals 138 sv south of the subantarctic zone and the crozet plateau or 150 sv including flow in the subantarctic zone the transport of the acc out of the south atlantic sector appears to be higher than the transport into the south atlantic sector at drake passage with the extra transport most probably carried by upper layer and intermediate waters eddies are seen to be an important feature of the subantarctic zone where they help to modify the water masses antarctic intermediate water appears in two forms a saline 34 4 indian ocean variety and a fresh 34 2 atlantic ocean variety the atlantic variety is freshest at the polar front and occupies the southern half of the subantarctic zone within the eddies in the central subantarctic zone there is interleaving between these two forms of antarctic intermediate water north atlantic deep water is unable to cross the southwest indian ridge but can pass south of the crozet plateau in the form of circumpolar deep water which is slightly more saline 34 75 than at drake passage 34 73

amalgamation surfaces bed thicknesses and dish structures in sand rich submarine fans numeric differences in channelized and unchannelized deposits and their diagnostic value abstract hydraulic differences between channelized and unchannelized flows in sand rich submarine fans result in different distributions of amalgamation surfaces bed thicknesses and dish structures in successions of these two different environments distribution trends of these fabrics were quantified for the sand rich fans of the reiselsberger sandstein cenomanian turonian these trends can be used as criteria to distinguish channelized from unchannelized paleoenvironments of sand rich submarine fans amalgamation surfaces in the studied fans channelized regions are considerably more abundant than in the unchannelized fan areas in unchannelized deposits tabular amalgamation surfaces outnumber nontabular ones whereas the opposite occurs in channelized successions these results indicate a higher degree of erosive power of gravity driven sediment flows in channels as a result of a greater flow thickness higher flow velocity and turbulence the average turbidite layer thickness in channelized successions is markedly greater than in unchannelized deposits layer as defined herein this is mainly attributed to the combined effects of differences in sediment fall out rate and the inefficiency of sand rich suspensions to transport sand in the proximal and channelized fan areas more sediment is deposited from a flow in the form of a layer than in distal unchannelized fan regions despite a higher degree of erosion in channels the greater average bed thickness in channel fills is a function of layer thickness and more frequent amalgamations bed as defined herein dish structures seem to be considerably more common in midfan than in outer fan successions this may indicate a higher sedimentation rate from individual suspension currents in midfan areas

forecasting the sst space time variability of the alboran sea with genetic algorithms we propose a nonlinear ocean forecasting technique based on a combination of genetic algorithms and empirical orthogonal function eof analysis the method is used to forecast the space time variability of the sea surface temperature sst in the alboran sea the genetic algorithm finds the equations that best describe the behaviour of the different temporal amplitude functions in the eof decomposition and therefore enables global forecasting of the future time variability

using earth tide induced water pressure changes to measure in situ permeability a comparison with long term pumping tests good constraints on hydrogeological properties are an important first step in any quantitative model of groundwater flow field estimation of permeability is difficult as it varies over orders of magnitude in natural systems and is scale dependent here we directly compare permeabilities inferred from tidal responses with conventional large scale long term pumping tests at the same site tidally induced water pressure changes recorded in wells are used to infer permeability at ten locations in a densely fractured sandstone unit each location is either an open hole well or a port in a multilevel monitoring well tidal response is compared at each location to the results of two conventional long term and large scale pumping tests performed at the same site we obtained consistent values between the methods for a range of site specific permeabilities varying from 10 15 m2 to 10 13 m2 for both open wells with large open intervals and multilevel monitoring well we conclude that the tidal analysis is able to capture passive and accurate estimates of permeability

variation in bed thickness in a turbidite succession dezadeash formation jurassic cretaceous yukon canada evidence of thinning upward and thickening upward cycles abstract analysis of the vertical variation in thickness of turbidites in an 883 in thick stratigraphic section of the dezadeash formation jurassic cretaceous yukon canada indicates that the turbidites are comprised of alternating sequences of thick beds and thin beds visual inspection reveals that 40 thick bedded cycles or megasequences are present fourier analysis indicates 38 cycles five different methods i e freehand signs of differences test correlation analysis least squares and moving averages used to determine the trend in bed thickness of the megasequences demonstrate that asymmetric cycles are present and most of these methods show that thickening upward trends are more common than thinning upward trends the best objective method for determining the asymmetry of megasequences appears to be correlation analysis viz pearson s spearman s and kendall s correlation coefficients and possibly the least squares method this particular section of the dezadeash formation is characterized by asymmetric cycles that are both common and statistically convincing and thickening upward sequences are more plentiful than thinning upward sequences

planktonic foraminiferal δ13c records from southern ocean sediment traps new estimates of the oceanic suess effect the carbon isotopic composition is measured for three species of planktonic foraminifera globigerina bulloides globorotalia inflata and neogloboquadrina pachyderma s from southern ocean sediment traps the sediment traps represent the annual flux of foraminifera in subtropical to polar frontal environments from the western pacific southern australia sector comparison between the seasonal 13c composition of the foraminifera and estimated 13c of dissolved inorganic carbon dic allows disequilibrium effects to be determined disequilibrium exhibits a latitudinal trend with greatest offsets from equilibrium at lower latitudes this effect causes a north to south increase in foraminiferal 13c while the 13cdic displays a decrease across these latitudes disequilibrium in g bulloides can be accounted for by changes in temperature the relationship between disequilibrium and temperature which we derive in this field study is consistent with the laboratory relationship of bemis et al 2000 corrected 13c for g bulloides is closely correlated to seasonal changes in nutrients at each site indicating the utility of g bulloides 13c as a nutrient tracer in southern ocean environments comparison between flux weighted sediment trap values and nearby core tops indicates a modern depletion in 13c which we attribute to the oceanic suess effect the imprint of this effect on the foraminiferal isotopes provides further evidence for the equilibration between surface waters and the atmosphere in the subantarctic zone

mechanisms of recharge in a fractured porous rock aquifer in a semi arid region abstract eleven porewater profiles in rock core from an upland exposed sandstone vadose zone in southern california with thickness varying between 10 and 62 m were analyzed for chloride cl concentration to examine recharge mechanisms estimate travel times in the vadose zone assess spatial and temporal variability of recharge and determine effects of land use changes on recharge as a function of their location and the local terrain the profiles were classified into four groups reflecting the range of site characteristics century to millennium average recharge varied from 4 to 23 mm y 1 corresponding to 1 moreover the temporal variability of recharge was estimated and along each profile past recharge rates calculated based on the sequence of cl concentrations in the vadose zone recharge rates increased at specific times coincident with historical changes in land use the consistency between the timing of land use modifications and changes in cl concentration and the match between observed and simulated cl concentration values in the vadose zone provide confidence in porewater age estimates travel times recharge estimates and reconstruction of recharge histories this study represents an advancement of the application of the chloride mass balance method to simultaneously determine recharge mechanisms and reconstruct location specific recharge histories in fractured porous rock aquifers the proposed approach can be applied worldwide at sites with similar climatic and geologic characteristics

oceanography of the subantarctic and polar frontal zones south of australia during summer setting for the saz sense study abstract this paper provides a description of the physical and chemical properties temperature salinity macro nutrient and oxygen concentrations and bulk biomass indicators chlorophyll and beam attenuation prevailing in the subantarctic zone and polar front zones south of tasmania australia during the sensitivity of the subantarctic zone to environmental change saz sense expedition carried out in the austral summer of 2007 phytoplankton biomass showed a characteristic north south gradient of decreasing chlorophyll from the subantarctic zone to polar frontal zone as well as a zonal gradient in the northern subantarctic zone with an increase in chlorophyll from southwest to southeast of tasmania the representativeness of the observations was assessed by comparison to previous studies including satellite observation of chlorophyll biomass over a 10 year period we consider the possible role of spatial differences in i ocean water masses and frontal systems ii upper mixed layer stratification at three process stations and iii nutrient availability in controlling the observed variations in phytoplankton biomass in the region zonal gradients of the basic oceanographic physical and chemical conditions in the subantarctic zone were relatively small and therefore unlikely to control the three fold west to east differences observed in the accumulation of phytoplankton biomass the zonal variation in subantarctic zone chlorophyll biomass appears to be driven at least partly by greater micro nutrient iron supply to the waters east of tasmania as reported also by others bowie et al 2009 mongin et al 2011a despite this condition the region of higher phytoplankton biomass to the southeast of tasmania was only marginally more productive than the region of lower biomass west of tasmania and south of the polar front and exported less particulate carbon than the lower biomass waters jacquet et al 2011

circulation and seasonal evolution of polar waters south of australia implications for iron fertilization of the southern ocean abstract the southern ocean iron release experiment soiree was carried out in late summer february 1999 south of australia 61 s 140 e this region of the southern antarctic zone az s between the southern branch of the polar front pf and the southern front of the antarctic circumpolar current saacf is characterized by weak currents and is remote from the influence of sea ice or coastal waters the soiree site exhibits high nutrient concentrations year round phosphate nitrate and silicate remain above 10 m low chlorophyll accumulations