rossby waves in the tropical north pacific and their role in decadal thermocline variability abstract a band of enhanced thermocline variability at 10 15 n in the pacific found in nature also occurs in an ocean general circulation model forced with observed fluxes of momentum heat and freshwater over the period 1958 97 the variability in the model is primarily associated with long baroclinic rossby waves characterized by periods in the decadal range 7 10 yr the waves are forced by westward propagating ekman pumping anomalies east of the date line and propagate at a speed of 13 cm s 1 which is slower than the phase speed of the first mode unforced baroclinic waves 15 16 cm s 1 west of the date line the correlations between thermocline displacements and local ekman pumping are relatively small and the ocean signals have a phase speed of 20 cm s 1 very similar to the phase speed of the first baroclinic mode in the western half of the basin 18 20 cm s 1 the phase speeds of the ocean model signals have been estimated using cospectral analysis while the wkb approximation has been us

coupling of biennial oceanic rossby waves with the overlying atmosphere in the pacific basin abstract anomalies of topex poseidon sea level height slh ncep sea surface temperature sst and ecmwf meridional surface wind msw and derived wind stress curl wsc are mapped biweekly over the global ocean from 60 s to 60 n for two years from 1993 to 1994 these anomalies i e differences from the average over the two years allow one cycle of biennial climate change to be examined with the paucity of temporal degrees of freedom mitigated by greater numbers of spatial degrees of freedom time longitude diagrams of slh anomalies reveal biennial rossby waves in the pacific ocean with westward phase speeds in the extratropics tropics faster slower than expected of free biennial rossby waves complex empirical orthogonal function analysis of slh sst msw and wsc anomalies finds the beta refraction pattern of these biennial rossby waves in all four variables over most of the eastern central pacific ocean suggesting that oceanic rossby waves there are coupled with the overlying atmosphere the

rare earth elements and neodymium isotopes in sedimentary organic matter abstract we report rare earth element ree and neodymium nd isotope data for the organic fraction of sediments collected from various depositional environments i e rivers n 25 estuaries n 18 open ocean settings n 15 and cold seeps n 12 sedimentary organic matter som was extracted using a mixed hydrogen peroxide nitric acid solution 20 h2o2 0 02 m hno3 after removal of carbonate and oxy hydroxide phases with dilute hydrochloric acid 0 25 m hcl a series of experimental tests indicate that extraction of sedimentary organic compounds using h2o2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates however this contamination is expected to be minor for ree because measured concentrations in h2o2 leachates are about two orders of magnitude higher than in the above mentioned phases the mean ree concentrations determined in the h2o2 leachates for samples from rivers estuaries coastal seas and open ocean settings yield relatively similar levels with ree 109 86 ppm mean s n 58 the organic fractions leached from cold seep sediments display even higher concentration levels 285 150 ppm mean s n 12 the h2o2 leachates for most sediments exhibit remarkably similar shale normalized ree patterns all characterized by a mid ree enrichment compared to the other ree this suggests that the distribution of ree in leached sedimentary organic phases is controlled primarily by biogeochemical processes rather than by the composition of the source from which they derive e g pore river or sea water the nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions in contrast the som extracted from marine sediments display end values that typically range between the end signatures for terrestrial organic matter inferred from the analysis of the sedimentary detrital fractions and marine organic matter inferred from the analysis of local surface seawater a notable exception is the case of organic matter om fractions leached from cold seep sediment samples which sometimes exhibit end values markedly different from both terrigenous and surface seawater signatures this suggests that a significant fraction of organic compounds in these sediments may be derived from chemosynthetic processes recycling pore water ree characterized by a distinct isotopic composition overall our results confirm that organic matter probably plays an important role in the oceanic ree budget through direct scavenging and remineralization within the water column both the high ree abundances and the shape of shale normalized patterns for leached som also suggest that om degradation in sub surface marine sediments during early diagenesis could control to a large extent the distribution of ree in pore waters benthic fluxes of organic bound ree could hence substantially contribute to the exchange processes between particulates and seawater that take place at ocean margins neodymium isotopes could provide useful information for tracing the origin terrestrial versus marine and geographical provenance of organic matter with potential applications in paleoceanography in particular future studies should further investigate the potential of nd isotopes in organic compounds preserved in sedimentary records for reconstructing past variations of surface ocean circulation

a tale of shales the relative roles of production decomposition and dilution in the accumulation of organic rich strata middle upper devonian appalachian basin abstract a new consensus on the processes responsible for organic carbon burial in ancient epeiric seas has emerged more firmly grounded in the uniformitarian framework of modern oceanography and biogeochemistry this consensus recognizes the interdependent roles of sedimentation primary production and microbial metabolism in favor of earlier end member models e g production vs preservation in this study one of the classic stratigraphic sequences upon which the preservation end member was based is re interpreted in light of this new consensus the study employs an extensive new sedimentological biogeochemical database from cores drilled in western new york the database spans over 500 m and 15 my of devonian deposition in the appalachian basin and provides a framework for comparative study of organic matter burial the major conclusions are 1 few organic rich units were deposited under pervasive anoxic sulfidic water columns 2 establishment and breakdown of seasonal thermoclines on annual or longer timescales were the predominant mode of stratification and 3 under such conditions remineralization of bio limiting nutrients may have played a key role in organic matter burial by creating a eutrophication pump this pump may have augmented an already rising nutrient inventory such that productivity levels exceeded the threshold required for development of suboxic to anoxic conditions in sediments and episodically in bottom waters a final conclusion asserts that the master variable for organic matter accumulation was relative sea level change which exerted influence on clastic dilution preservation and production processes sea level rise events led to sediment starvation and organic carbon concentration in distal basin sediments as well as to decreased effectiveness of seasonal mixing and thus longer build up intervals for remineralized nutrients episodic mixing of nutrient enriched bottom waters led to enhanced production ultimately increased clastic sediment delivery and water column mixing during relative sea level fall diluted surface sediment organic content such that respiratory demand could be met by increased oxygen supply thus terminating deposition of strata enriched in organic carbon

numerical paleoceanographic study of the early jurassic transcontinental laurasian seaway the forces governing marine circulation of a meridional transcontinental seaway is explored with the princeton ocean model the jurassic laurasian seaway which connected the low latitude tethys ocean with the arctic sea is modeled quantitatively the global ocean is found to have a profound influence on seaway dynamics a north south density difference and hence sea level difference of the global ocean was probably the main factor in forcing the seaway flow when the tethys waters were the denser water the net seaway flow was southward and conversely it was northward for denser arctic waters marine bioprovincial boundaries and sediment data indicate that the seaway probably was dominated by boreal faunal groups and reduced salinities several times in the jurassic the model results suggest that this can be explained by southward flowing seaway currents which may have been related to an oceanic thermohaline circulation where no northern high latitude deep convection occurred

shallow marine sedimentary processes in the late devonian catskill sea new york state shallow marine strata of the upper devonian west falls group in south central new york comprise centimetre to decimetre thick sheetlike to lenticular beds of sandstone and siltstone interbedded with mudstone unidirectional current scour marks and tool marks occur on the basal erosion surfaces of the sandstones their internal structures are hummocky cross strata of various styles planar laminae and wave ripple cross laminae with characteristic vertical and lateral transitions among them vertical burrows of the skolithos ichnofacies dominate upper portions of sandstone beds whereas mudstones and silt stones contain mainly horizontal burrows of the cruziana ichnofacies transported and in situ shelly fossils occur throughout in places concentrated in coquinite lenses large scale 15 to 30 in bedding sequences are characterized by upward thickening and coarsening of sandstone beds increase in amalgamated hummocky cross strata coquinites plant debris and bivalves followed by abrupt fining and thinning of beds the depositional environment is interpreted as a shallow marine shelf episodically influenced by intense tropical storms hurricanes individual sandstone beds were deposited by spatially decelerating combined flows where an initially strong offshore directed flow component decreased in time relative to the oscillatory flow component large scale bedding sequences reflect changes in storm combined current intensity and deposition rate strong eustatic control is unlikely and there is no evidence of changing wave climate instead these sequences may be associated with delta lobe progradation and or offshore bar development

sedimentary fe mn oxyhydroxides as paleoceanographic archives and the role of aeolian flux in regulating oceanic dissolved ree in the marine environment authigenic ferromanganese fe mn oxides precipitate from seawater incorporating many dissolved trace elements such as nd pb whose isotopic composition is a direct proxy for ambient seawater thus isotopic studies of the fe mn oxyhydroxide component leached from sedimentary records can provide information on changes in erosional input or ocean circulation changes such studies may be complicated however by the presence of detrital material containing a fe mn oxide component which may mask the true seawater signal in addition the formation of fe mn oxyhydroxides in the marine environment remains poorly understood in particular the phase carbonates detrital particles that controls the delivery of authigenic fe mn oxides to the sediments has not yet been determined in this study we have analysed the ree and nd isotopic compositions of fe mn oxyhydroxide fractions dispersed in marine sediment cores from the cape and angola basins in the se atlantic cruise images ii for the angola basin deep sea core located at 1000 km south of the congo river mouth both the ree and nd isotopic compositions nd measured in recent fe mn oxyhydroxide fractions are typical of congo river borne fe mn oxides this shows that preformed fe mn oxides associated with detrital fractions can locally contaminate the seawater signal recorded by authigenic oxyhydroxides by contrast examination of ree distributions nd isotope data and mass accumulation rates in cape basin sediments shows paradoxically that the flux of fe mn oxides to sediments is controlled by aeolian particles from the nearby namib desert even though their ree and nd compositions point clearly to an authigenic origin it is proposed that partial dissolution of aeolian dust occurs in the water column releasing into solution its easily leachable fe mn component the dissolved fe2 and mn2 would then fuel the reprecipitation of authigenic fe mn oxyhydroxides scavenging additional dissolved trace elements from the ocean most probably from deep water masses in this case calculations suggest that aeolian deposition acts as a net sink for dissolved nd in the cape basin rather than a source and allows us to estimate the rate of removal of dissolved nd associated with atmospheric deposition yielding a global oceanic residence time for nd nd of between 500 and 1400 years

lower jurassic epicontinental carbonates and mudstones from england and wales chemostratigraphic signals and the early toarcian anoxic event sections through lower jurassic epicontinental carbonates from southern britain junction bed and equivalent show a positive carbon isotope excursion 13ccarbonate detectable in bulk rock in the falciferum zone of the lower toarcian isotopic data from organic matter in more clay rich sections from wales and north east england together with determinations on belemnite calcite indicate that highest 13c values are localized in the upper exaratum subzone of the falciferum zone levels of particular enrichment in organic carbon were developed in the early to mid exaratum subzone and hence pre date this 13c maximum these phenomena reflect the impact of the early toarcian oceanic anoxic event in the british area similar isotopic trends have been recorded in other toarcian sections from tethyan europe and are interpreted as reflecting the chemistry of sea water on the assumption of isotopic correlation between the english and tethyan sections the 13c maximum would be everywhere dated as latest exaratum subzone in terms of the north european ammonite scheme absolute oxygen isotope values in carbonates probably reflect both early diagenetic cementation and later temperature related burial diagenesis although a palaeotemperature maximum is tentatively identified as characterizing the early falciferum zone subsequent climatic deterioration may have been triggered by drawdown of co2 related to regional excess carbon burial during the oceanic anoxic event using the positive 13c excursion as a correlative level in sections from different faunal provinces britain italy and spain implies that lower toarcian zonal stratigraphy is diachronous between northern and southern europe there is evidence for partitioning of water masses between the north european shelf and the tethyan continental margin during the early jurassic

the effects of diagenetic processes and fluid migration on rare earth element and organic matter distribution in seep related sediments a case study from the south china sea abstract methane seepage is an important factor governing microbial activity in marine sediments although its impact on the distribution of rare earth elements rees and organic matter in sediments is unclear here we report isotope signatures of organic 13ctoc and inorganic 13ctic carbon as well as total rees contents of core sediments collected from a well characterized seep area on the northern south china sea previous studies have identified sediments corresponding to three methane release events mres in the studied core mre i at 4 0 5 5 m mre ii at 7 4 8 2 m and mre iii at 10 0 11 5 m depth intervals increased methane flux and reducing bottom waters during mre i resulted in a higher accumulation of marine sourced organic matter as indicated by lower c n ratios and higher 13ctoc values compared with those of mres ii and iii sediments deposited during mre i have relatively low total ree contents which may be related to reduced ree adsorption on mn oxyhydroxides however the absence of ce anomaly at mre i is more likely due to the detrital input that obscures the original ce anomaly in the mre iii sediments a weak negative eu anomaly relative to that in the mre i and ii may be attributed to the reduction of eu3 to eu2 under strongly reducing conditions that caused by intense methane seepage these observations demonstrate that fluid flow may have an important effect on the distribution of both organic matter and rees in methane rich marine sediments

balancing the global oceanic neodymium budget evaluating the role of groundwater the distinctly different end 0 values of the atlantic indian and pacific oceans requires that the residence time of nd in the ocean i e nd be on the order of or less than the ocean mixing time of 500 1500 yr however estimates of nd based on river influxes range from 4000 to 15 000 yr thus exceeding the ocean mixing time in order to reconcile the oceanic nd budget and lower the residence time by roughly a factor of 10 an additional as yet unidentified and hence missing nd flux to the ocean is necessary dissolution of materials deposited on continental margins has previously been proposed as a source of the missing flux in this contribution submarine groundwater discharge sgd is examined as a possible source of the missing nd flux neodymium concentrations n 730 and end 0 values n 58 for groundwaters were obtained from the literature in order to establish representative groundwater values mean groundwater nd concentrations and end 0 values were used along with recent estimates of the terrestrial freshwater component of sgd 6 of river discharge on a global basis to test whether groundwater discharge to the coastal oceans could account for the missing flux employing mean nd concentrations of the compiled data base i e 31 8 nmol kg for all 730 analyses and 11 3 nmol kg for 141 groundwater samples from a coastal aquifer the global terrestrialderived sgd flux of nd is estimated to range between 2 9 10 7 and 8 1 10 7 mol yr these estimates are of the same order of magnitude and within a factor of 2 of the missing nd flux i e 5 4 10 7 mol yr applying the sgd nd flux estimates the global average end 0 of sgd is predicted to be 9 1 which is similar to our estimate for the missing nd flux 9 2 and in agreement with the mean s d end 0 measured in groundwaters i e end 0 8 9 4 2 the similarities in the estimated sgd nd flux and corresponding end 0 values to the magnitude and isotope composition of the missing nd flux are compelling and suggest that discharge of groundwater to the oceans could account for the missing nd flux future investigations should focus on quantifying the nd concentrations and isotope compositions of groundwater from coastal aquifers from a variety of coastal settings as well as the important geochemical reactions that effect nd concentrations in subterranean estuaries in order to better constrain contributions of sgd to the oceanic nd budget

off equatorial influence upon pacific equatorial dynamic height variability during the 1982 1983 el nino southern oscillation event anomalous sea level anomalous observed dynamic height 0 400 dbar and anomalous model dynamic height are compared at the locations of 13 island sea level stations in the tropical pacific for each 2 month interval of the 4 year period 1979 to 1982 sea level compares well with both observed dynamic height 0 400 dbar based on temperature depth observations made by volunteer observing ships and model dynamic height derived from a linear two layer wind driven model the cross correlation between sea level and either of the dynamic heights is generally greater than 0 75 the ratio of root mean square rms differences about the mean annual cycle of the sea level to rms differences of either of the dynamic heights is approximately unity starting in 1981 off equatorial rossby wave activity propagated toward the western boundary of the pacific basin this also occurred in model dynamic height both north and south of the equator yet neither sea level observations nor observed dynamic height has the spatial and temporal resolution to establish a connection between the off equatorial rossby wave activity and the equatorial kelvin wave activity in the western boundary region on the other hand the model dynamic height does have this capability therefore at the western boundary the model rossby wave activity is found to have excited coastally trapped kelvin munk wave activity which transmitted the anomalous sea level equatorward at the equator this model coastally trapped wave activity excited eastward propagating equatorial kelvin waves yielding a pair of anomalous peaks in dynamic height variability in the eastern equatorial pacific associated with the 1982 1983 el nino southern oscillation enso event the evolution of these two peaks in anomalous dynamic height associated with the 1982 1983 enso event is examined at eight locations in the tropical and equatorial pacific the major peak originated in the off equatorial south pacific and coincided with the wintertime 1982 1983 el nino event in the eastern equatorial pacific the secondary peak originated in the off equatorial north pacific and coincided with the anomalous peak which occurred in the eastern equatorial pacific the summer before the 1982 1983 enso event

submarine groundwater discharge is an important net source of light and middle rees to coastal waters of the indian river lagoon florida usa abstract porewater i e groundwater samples were collected from multi level piezometers across the freshwater saltwater seepage face within the indian river lagoon subterranean estuary along florida s usa atlantic coast for analysis of the rare earth elements ree surface water samples for ree analysis were also collected from the water column of the indian river lagoon as well as two local rivers eau gallie river crane creek that flow into the lagoon within the study area concentrations of rees in porewaters from the subterranean estuary are 10 100 times higher than typical seawater values e g nd ranges from 217 to 2409 pmol kg 1 with submarine groundwater discharge sgd at the freshwater saltwater seepage face exhibiting the highest ree concentrations the elevated ree concentrations for sgd at the seepage face are too high to be the result of simple binary mixing between a seawater end member and local terrestrial sgd instead the high ree concentrations indicate that geochemical reactions occurring within the subterranean estuary contribute substantially to the ree cycle a simple mass balance model is used to investigate the cycling of rees in the indian river lagoon and its underlying subterranean estuary mass balance modeling reveals that the indian river lagoon is approximately at steady state with respect to the ree fluxes into and out of the lagoon however the subterranean estuary is not at steady state with respect to the ree fluxes specifically the model suggests that the sgd nd flux for example exported from the subterranean estuary to the overlying lagoon waters exceeds the combined input to the subterranean estuary from terrestrial sgd and recirculating marine sgd by on average 100 mmol day 1 the mass balance model also reveals that the subterranean estuary is a net source of light rees lree and middle rees mree to the overlying lagoon waters but acts as a sink for the heavy rees hree geochemical modeling and statistical analysis further suggests that this fractionation occurs in part due to the coupling between ree cycling and iron redox cycling within the indian river lagoon subterranean estuary the net sgd flux of nd to the indian river lagoon is 7 fold larger than the local effective river flux to these coastal waters this previously unrecognized source of nd to the coastal ocean could conceivably be important to the global oceanic nd budget and help to resolve the oceanic nd paradox by accounting for a substantial fraction of the hypothesized missing nd flux to the ocean

influence of the antarctic circumpolar wave on australian precipitation from 1958 to 1997 abstract year to year changes are found in australian precipitation app covarying with those in sea surface temperature sst and troposphere moisture flux mf over the three oceans surrounding australia for 40 yr from 1958 to 1997 australia s wet dry years are associated with warm cool sst anomalies surrounding australia and convergent divergent mf anomalies directly overhead differences in app sst between wet and dry years can reach 0 75 m 1 2 c in northeast australia subtropical indian ocean wet dry years often occur during la nina el nino but significant differences in covarying sst mf and app anomalies from one el nino to the next are found indicating that regional climate changes also influence app covarying sst and mf anomalies on basin space scales and interannual timescales are found to take 2 3 yr to propagate eastward from africa to australia this propagation occurs in association with the antarctic circumpolar wave acw in the southern ocean the north branch of th

rare earth elements and radiogenic strontium isotopes in carbonate minerals reveal diagenetic influence in shales and limestones in the appalachian basin abstract rare earth element ree signatures are often applied to interpret paleoenvironmental conditions in sedimentary basins however the complicated diagenetic histories in dynamic depositional environments can affect interpretation of measured ree signatures prior studies on ree content in shales and limestones indicated that ree in specific mineral phases may provide unique information concerning diagenetic reactions occurring in sedimentary rocks during burial and compaction application of sequential extraction techniques to target ree signatures in specific mineral fractions may provide greater insight into the complex processes that occurred during diagenesis and catagenesis thus using this technique this study provides a detailed account for ree 87sr 86sr and 13c in the carbonate fraction of the marcellus shale and adjacent formations in the appalachian basin a suite of 49 rock samples collected from two cores recovered from monongalia county west virginia usa was analyzed the results showed that the carbonate concretions in calcareous shales and carbonate cements in black shales were very distinct the ree plus yttrium rey were more concentrated in the carbonate concretions than in the carbonate cements the carbonate concretions displayed rey patterns that are closely similar to modern seawater while mree enrichment was observed in the carbonate cements likewise the 87sr 86sr values in the carbonate concretions were similar to those measured for unaltered middle devonian carbonates while the 87sr 86sr in the carbonate cements were much more radiogenic this observation indicates that the carbonate cement could have been inherited radiogenic 87sr expulsed from clays during illite smectite transition overall this study demonstrated two distinct processes involved with controlling the carbonate geochemistry within appalachian basin shales and limestones one fraction displaying minimal diagenetic alteration relative to depositional conditions carbonate concretions in calcareous shales and limestone carbonate in limestones and another fraction displaying the evidence for extensive chemical alteration during illite smectite transition and catagenesis carbonate cements in black shales in addition highly variable and significant enrichments of u and mo demonstrate that the union spring member and the lower oatka creek member of the marcellus shale in the southwestern appalachian basin mseel site were deposited under mainly anoxic environment whereas intermitted episodes of dysoxic to perhaps oxic conditions occurred during the deposition of the upper oatka creek member

a global quasi biennial wave in surface temperature and pressure and its decadal modulation from 1900 to 1994 zonal wave number frequency spectra of surface temperature st and sea level pressure slp anomalies extending around the global tropical ocean at 10 n from 1950 to 1997 display significant peaks for 2 0 and 2 4 year periods dominated by eastward propagating zonal wave numbers of global scale applying complex principal component analysis to quasi biennial st slp and surface wind sw anomalies for 25 years from 1973 to 1997 separates this global quasi biennial wave gbw from corresponding global standing modes with patterns and evolution of the former similar to those observed in the global el nino southern oscillation wave white and cayan 2000 but centered on the equatorial waveguide and taking only 3 to 4 years instead of 4 to 6 years to transit the global tropical ocean at 0 30 to 0 40 m s 1 we find the gbw contributing to the quasi biennial signal in nino 3 st and slp indices with amplitude twice that of global standing mode in the gbw the ocean forces the atmosphere with sw anomalies directed toward warm sea surface temperature anomalies while the atmosphere forces the ocean with sw induced kelvin waves on the equator and sw induced sensible plus latent heat flux and or vertical mixing anomalies elsewhere both advancing st anomalies eastward examining the gbw from 1900 to 1994 finds its amplitude modulated by the decadal signal of 10 year periodicity robust weak when tropical temperature gradients and trade winds were stronger weaker than normal

the sedimentary flux of dissolved rare earth elements to the ocean abstract we determined pore fluid rare earth element ree concentrations in near surface sediments retrieved from the continental margin off oregon and california usa these sites represent shelf to slope settings which lie above within and below the oxygen minimum zone of the northeast pacific the sediments are characterized by varying degrees of net iron reduction with pore fluids from the shelf sites being generally ferruginous and the slope sediments having less pronounced iron reduction zones that originate deeper in the sediment package ree concentrations show maxima in shallow upper 2 10 cm subsurface pore fluids across all sites with concentrations that rise more than two orders of magnitude higher than seawater these pore fluid enrichments highlight the importance of a sedimentary source of rees to the ocean s water column here we use our measurements to estimate the diffusive flux of nd out of ocean sediments resulting in a global flux between 18 and 110 10 6 mol nd yr 1 while we do assume that our pore fluid profiles as well as the very limited data previously published are representative of a wide array of ocean environments this calculated flux can account for the modeled missing nd source flux 76 10 6 mol nd yr 1 in global budgets arsouze et al 2009 pore fluid normalized ree patterns show distinct variation in the middle ree and heavy ree enrichments with sediment depth and amongst sites these patterns show that the heavy ree enrichment of pore fluids at our deep slope site 3000 m water depth is closest to the heavy ree enrichment of seawater this observation supports the view that ree cycling within the upper ten centimeters of deep sea marine sediments as opposed to shallower continental shelf and slope sediments plays a significant role in controlling the integrated global ree flux from the pore fluids and consequently the broad scale ree pattern in seawater

tracing sources and cycling of phosphorus in peru margin sediments using oxygen isotopes in authigenic and detrital phosphates abstract many bio geochemical processes that bring about changes in sediment chemistry normally begin at the sediment water interface continue at depth within the sediment column and may persist throughout the lifetime of sediments because of the differential reactivity of sedimentary phosphate phases in response to diagenesis dissolution precipitation and biological cycling the oxygen isotope ratios of phosphate 18op can carry a distinct signature of these processes as well as inform on the origin of specific p phases here we present results of sequential sediment extraction sedex analyses combined with 18op measurements aimed at characterizing authigenic and detrital phosphate phases in continental margin sediments from three sites sites 1227 1228 and 1229 along the peru margin collected during odp leg 201 our results show that the amount of p in different reservoirs varies significantly in the upper 50 m of the sediment column but with a consistent pattern for example detrital p is highest in siliciclastic rich layers the 18op values of authigenic phosphate vary between 20 2 and 24 8 and can be classified into at least two major groups authigenic phosphate precipitated at near the sediment water interface in equilibrium with paleo water oxygen isotope ratios 18ow and temperature and phosphate derived from hydrolysis of organic matter porg with subsequent incomplete to complete re equlibration and precipitated deeper in the sediments column the 18op values of detrital phosphate which vary from 7 7 15 4 suggest two possible terrigenous sources and their mixtures in different proportions phosphate from igneous metamorphic rocks and phosphate precipitated in source regions in equilibrium with 18ow of meteoric water more importantly original isotopic compositions of at least one phase of authigenic phosphates and all detrital phosphates are not altered by diagenesis and other biogeochemical changes within the sediment column these findings help to understand the origin and provenance of p phases and paleoenvironmental conditions at near the sediment water interface and to infer post depositional activities within the sediment column

seawater rare earth element patterns preserved in apatite of pennsylvanian conodonts past workers have used rare earth element patterns recorded in biogenic apatite as proxies for original seawater chemistry to explore the potency of this approach we analyzed pennsylvanian conodonts from limestones gray shales and black shales of the fort scott and pawnee formations desmoinesian and swope and dennis formations missourian in kansas missouri and iowa u s a analysis of individual platform conodonts from seven taxa using laser ablation inductively coupled plasma mass spectrometry la icp ms revealed a consistent enrichment in the middle rare earth elements mree analogous mree enrichment has been observed in authigenic apatite and bulk samples of phosphate rich black shales from the same formations importantly however phosphate depleted shales intimately associated with the p rich intervals are relatively depleted in mree these antithetic patterns argue convincingly for secondary migration from the bulk sediment into the phosphate and the extent of mree enrichment in the conodonts is correlated positively with the total ree content mree enrichment in conodonts does not vary systematically as a function of lithology stratigraphic level conodont genus geographic location or with independent estimates of paleoredox conditions in the bottom waters collectively these results argue for postmortem diagenetic ree uptake resulting in a pronounced and progressive mree enrichment any cerium anomalies if initially present were masked by diagenetic uptake of ree paleoenvironmental interpretations of conodont ree particularly for samples exhibiting mree enrichment should therefore be viewed with caution

sedimentary corg p ratios paleocean ventilation and phanerozoic atmospheric po2 the corg p ratios of organic rich facies tocn1 exhibit considerable variation through the phanerozoic from b10 1 in the permian phosphoria formation to n1000 1 in some devonian black shales relative to the composition of phytoplankton c p 106 1 which provide the bulk of organic c and p to organic rich marine sediments the range of phanerozoic sedimentary corg p ratios largely reflects the influence of benthic redox conditions on diagenetic pathways of c and p remobilization enhanced preservationoforganiccatlowerredoxpotentials combinedwithenhancedsedimentaryretentionofremineralizedorganicpathigher redox potentials results in a strong relationship between benthic redox conditions and sedimentary corg p ratios the strong secular coherence of the phanerozoic corg p record i e limited variation within narrow time slices suggests that these ratios are controlled primarily by factors influencing benthic redox conditions on a global scale such as atmospheric po2 inversion and scaling of the phanerozoic corg p record yields a new atmospheric po2 model that has strong similarities to existing models based on elemental and isotopic mass balances yet differs in some potentially significant respects in particular the new model suggests that atmospheric po2 wasmarkedlylowerduringtheearlytomiddlepaleozoicthanpreviouslyinferred duringmostofthedevonian atmospherico2levels mayhavebeensufficientlylow b13 astopreventthesustainedcombustionofplantmaterial thisfeatureofthemodelmayaccount for ananomalous gapinthefossilcharcoalrecordduringthedevonian theredox dependentburialofpintheoceanresults inpositive and negative feedback mechanisms that tend to stabilize atmospheric oxygen concentrations on geologic timescales temporal variations in the burial of p relative to c suggest that the strength of these feedback mechanisms varied over the phanerozoic 2007 elsevier b v all rights reserved

an improved real time global sea surface temperature analysis abstract the monthly global sea surface temperature sst analysis of reynolds using real time in situ and satellite sst data has now been improved by using sea ice data to simulate ssts in ice covered regions the simulated ssts now become the external boundary condition for the analysis solution this technique eliminates any high latitude satellite biases and extends the analysis to the ice edge the analysis with the ice data has been computed for the period january 1982 to present

climate of the supercontinent pangea numerous climate models predict that the geography of the supercontinent pangea was conducive to the establishment of a megamonsoonal circulation in general geologic evidence supports the hypothesis of a megamonsoon that reached maximum strength in the triassic pangea in the late carboniferous had widespread peat formation in what is now central and eastern north america and europe and relatively dry conditions on the colorado plateau the equatorial region of the continent became drier through the end of the carboniferous by the permian the equatorial region of pangea was dry and indicators of aridity and rainfall seasonality became more widespread wind directions from colorado plateau eolian sandstones are consistent with an increasing influence of monsoonal circulation at this time in the triassic climate in the colorado plateau region became relatively wet though still seasonal and the few eolian sandstones indicate a major shift in wind direction at that time in addition sedimentation

an integrated assessment of a type euxinic deposit evidence for multiple controls on black shale deposition in the middle devonian oatka creek formation an integrated lithologic paleontologic and multi proxy geochemical study of the middle devonian oatka creek formation a black shale in the northern appalachian basin indicates that a number of different factors contributed to organic carbon rich black shale deposition conditions leading to this organic rich sedimentary deposit were ultimately controlled by a relative sealevel rise dominantly eustatic but with possible contributions from local tectonics which cut off the supply of carbonate to the basin geochemical proxy evidence such as mo ti fe ti corg spy and 34spy suggests that as sealevel continued to rise after the carbonate supply was cut off a threshold was crossed at which point conditions in the basin shifted from dominantly anoxic to dominantly euxinic anoxic sulfidic bottom waters concurrent with the shift to dominantly euxinic conditions the supply of siliciclastic sediments was cut off resulting in a condensed horizon as evidenced by the elemental ratios of si al and k fe mg and the relative concentration of eolian silt as determined petrographically and from scanning electron microscopy sediment starvation in the basin appears to have facilitated the biogeochemical re cycling of c n and p specifically the elemental ratios of c n and p and the stable carbon isotope composition of organic matter suggest that the preferential regeneration of p under anoxic conditions and of n during the oxic phase of oxic anoxic oscillation led to enhanced primary production in surface waters thereby maintaining euxinic conditions in the bottom waters through respiration of settling organic matter finally it is observed that though conditions in the basin seem to have remained consistently anoxic sulfidic for some time after the initial shift to euxinic conditions a progressive increase in siliciclastic sedimentation led to a corresponding decrease in the enrichment of various redox related elements illustrating the overriding control that sedimentation can have on geochemical proxy records

the effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern cascadia accretionary margin analytical challenges in obtaining high quality measurements of rare earth elements rees from small pore fluid volumes have limited the application of rees as deep fluid geochemical tracers using a recently developed analytical technique we analyzed rees from pore fluids collected from sites u1325 and u1329 drilled on the northern cascadia margin during the integrated ocean drilling program iodp expedition 311 to investigate the ree behavior during diagenesis and their utility as tracers of deep fluid migration these sites were selected because they represent contrasting settings on an accretionary margin a ponded basin at the toe of the margin and the landward tofino basin near the shelf s edge ree concentrations of pore fluid in the methanogenic zone at sites u1325 and u1329 correlate positively with concentrations of dissolved organic carbon doc and alkalinity fractionations across the ree series are driven by preferential complexation of the heavy rees simultaneous enrichment of diagenetic indicators doc and alkalinity and of rees in particular the heavy elements ho to lu suggests that the heavy rees are released during particulate organic carbon poc degradation and are subsequently chelated by doc ree concentrations are greater at site u1325 a site where shorter residence times of poc in sulfate bearing redox zones may enhance ree burial efficiency within sulfidic and methanogenic sediment zones where ree release ensues cross plots of la concentrations versus cl li and sr delineate a distinct field for the deep fluids z 75 mbsf at site u1329 and indicate the presence of a fluid not observed at the other sites drilled on the cascadia margin changes in ree patterns the presence of a positive eu anomaly and other available geochemical data for this site suggest a complex hydrology and possible interaction with the igneous crescent terrane located east of the drilled transect

slow el nino southern oscillation boundary waves anomalies of sea surface temperature sst and heat storage in the upper 400 m of ocean hs400 for 13 years from 1979 to 1991 are mapped onto a 2 latitude by 5 longitude grid each month over most of the global ocean from 30 s to 60 n time sequences at every grid location are band pass filtered to reveal el nino southern oscillation enso signals on period scales ranging from 2 to 7 years time distance diagrams are constructed along the equator and eastern boundary of the north pacific north atlantic and south indian oceans these time distance diagrams display slow poleward propagation of equatorial enso signals consistently in hs400 and intermittently in sst in the north pacific ocean enso signals in hs400 take 9 18 months to propagate from the equator northward along the west coast of north america to the gulf of alaska in the north atlantic ocean enso signals in hs400 take 6 12 months to propagate from the equator along the west coast of africa to the strait of gibraltar in the south indian ocean enso signals in hs400 take 9 18 months to propagate poleward from the equator along the west coasts of indonesia and australia to perth speeds of poleward propagation of enso waves in both hs400 and sst along these eastern boundaries range from 5 to 30 cm s 1 these enso boundary waves propagate in the same direction as kelvin waves but with speeds an order of magnitude smaller they provide a remote and delayed influence upon enso activity in the middle latitude eastern boundary in each ocean time distance diagrams are also constructed along the western boundary and equator of the north pacific north atlantic and south pacific oceans these time distance diagrams display slow propagation of enso signals in sst and hs400 in both directions depending on the ocean in the north pacific ocean enso signals in both sst and hs400 propagate equatorward from taiwan to new guinea taking 6 18 months to make this transit moreover they arrive on the equator in phase with zonally propagating equatorial enso waves this indicates that enso activity in the western subtropical north pacific ocean influences enso activity in the western equatorial pacific ocean through slow equatorward propagation speeds of equatorward propagation of enso waves in both hs400 and sst along this western boundary range from 5 to 20 cm s 1 in the north atlantic and south pacific oceans this off equatorial influence is not possible since slow enso waves in hs400 propagate poleward along these western boundaries

fine scale la icp ms study of redox oscillations and reey cycling during the latest devonian hangenberg crisis moravian karst czech republic abstract trace elementsand reey distribution of thinly laminated limestone laminite and underlying pre event calciturbidite siphonodella praesulcata conodont zone deposited in association with the hangenberg black shale event were analyzed using laser ablation inductively coupled plasma mass spectrometry these deposits were also analyzed by carbonate petrography and scanning electron microscopy our study documents the origin of authigenic microbial limestones during the latest devonian hangenberg extinction event when unusual oceanic conditions appear to have enhanced precipitation of calcite within microbial carbonates detrital contamination of the calciturbidite and laminated limestone is very low as demonstrated by low contents of al zr ti and th these deposits display only limited degree of early diagenetic overprint of limestones and some of them fall within or very close to the seawater field elevated u and mo enrichments and covariation patterns reflect the episodic establishment of oxic to euxinic bottom condition during deposition of the laminite the oxic conditions that existed during accumulation of the underlying calciturbidite were likely the result of turbidity current introduction of oxygen into the bottom environment ree contents of both the laminite and calciturbidite are nearly ten times higher than those of most modern carbonates and similar to devonian microbialites from the canning basin calciturbidite display a prominent mreen bulge shale normalized ree patterns of the overlying laminite are similar to those of modern seawater and devonian microbialites from the canning basin lree depletion and progressive enrichments in heavier ree reflecting the dominance of authigenic carbonate phases minor contamination is bound to apatites siliciclastic minerals pyrites and organic matter the element content of authigenic phases benefited from fe and mn oxyhydroxide redox cycling negative ce and positive eu anomalies low y ho ratios and very low al al fe mn ratios suggest an influence of diluted high temperature hydrothermal fluids perhaps related to latest devonian rift magmatism in the eastern part of the rhenohercynian zone the proliferation of anachronistic facies following the devonian carboniferous d c extinction event recognized in moravia and traced worldwide seems to share some features in common with anachronistic carbonate sequences documented in the aftermath of the end permian mass extinction

authigenic carbonates from methane seeps of the northern congo fan microbial formation mechanism abstract authigenic carbonates were collected from methane seeps at hydrate hole at 3113 m water depth and diapir field at 2417 m water depth on the northern congo deep sea fan during rv meteor cruise m56 the carbonate samples analyzed here are nodules mainly composed of aragonite and high mg calcite abundant putative microbial carbonate rods and associated pyrite framboids were recognized within the carbonate matrix the 13c values of the hydrate hole carbonates range from 62 5 to 46 3 pdb while the 13c values of the diapir field carbonate are somewhat higher ranging from 40 7 to 30 7 pdb indicating that methane is the predominant carbon source at both locations relative enrichment of 18o 18o values as high as 5 2 pdb are probably related to localized destabilization of gas hydrate the total content of rare earth elements ree of 5 hno3 treated solutions derived from carbonate samples varies from 1 6 ppm to 42 5 ppm the shale normalized ree patterns all display positive ce anomalies ce ce 1 3 revealing that the carbonates precipitated under anoxic conditions a sample from hydrate hole shows a concentric lamination corresponding to fluctuations in 13c values as well as trace elements contents these fluctuations are presumed to reflect changes of seepage flux

diagenetic uptake of rare earth elements by conodont apatite abstract the rare earth element ree composition of bioapatite has long been used as a proxy for ancient seawater chemistry and paleomarine environmental reconstruction based on the assumption of preservation of a hydrogenous seawater derived ree signal recent work however has begun to question the provenance of rees in conodonts emphasizing the importance of rees released by the lithogenous fraction of the sediment and subsequently adsorbed onto conodont apatite in the burial environment here we investigate patterns of ree and trace element abundance in conodonts and their host sediments from the early to late ordovician huanghuachang and chenjiahe sections of hubei province south china several lines of evidence indicate that rees in the conodont samples were acquired mainly from clay minerals in the host sediment during burial diagenesis 1 rees in conodonts show a strong positive correlation to th and other lithogenic elements 2 conodonts and whole rock samples show general patterns of ree and trace element enrichment that are highly similar to each other and bear no resemblance to seawater elemental concentrations 3 similar patterns are observed in triassic conodonts and whole rock samples and 4 y ho ratios in conodonts are mostly 90 of rees from lithogenous sources conodonts show pronounced middle rare earth element mree enrichment a pattern that is unambiguously of diagenetic origin owing to its association with lower y ho ratios with increasing mree enrichment of conodont samples u concentrations and la n yb n ratios shift from high to low and mn concentrations from low to high these patterns suggest that conodont diagenesis was initiated at shallow burial depths under suboxic conditions i e in the zone of mn iv and fe iii reduction but continued at greater burial depths with most acquisition of secondary rees at later diagenetic stages our findings indicate that 1 conodont apatite frequently does not preserve a recognizable hydrogenous ree signal and 2 the results of many earlier studies in which rees in bioapatite were used as a paleoseawater proxy may need re evaluation

rare earth elements in cold seep carbonates from the niger delta abstract the circulation of methane rich fluids at cold seeps often leads to precipitation of authigenic carbonates mediated by microbial activity which can be used as archives of fluid seepage on continental margins in this study we have investigated the potential of using rare earth element ree concentrations in authigenic carbonates for tracing fluid sources and providing information on associated biogeochemical processes at cold seeps we have examined various chemical procedures for the analysis of ree in authigenic carbonates and present a robust method using dilute acetic acid solution that allows the extraction of ree from carbonate phases with reduced contamination from fe mn oxides and detrital minerals using this method we analysed a series of carbonate samples collected at various deep sea sites of active fluid seepage on the niger delta for their ree and trace element concentrations 13c and 18o values and 87sr 86sr isotope compositions we show that the ree composition of cold seep carbonates is controlled primarily by that of the fluid from which they have precipitated our results also suggest that significant ree fractionation can occur during carbonate precipitation which can be related to various degrees of ree complexation by organic versus carbonate ligands in response to changing pore water chemical composition for parameters such as carbonate alkalinity

rare earth element variation in phosphate nodules from midcontinent pennsylvanian cyclothems abstract the rare earth element ree geochemistry of phosphate nodules from eastern kansas and northeastern oklahoma is dominated by patterns that are generally flat or are enriched in middle ree mree flat patterns are typical of phosphate nodules preserved in thick shales and in nodules from shales deposited nearest to detrital sources the flat patterns are probably derived from terrigenous constituents in the host shale mree enrichment is evident in phosphate found in relatively thin shales and in distal shales we suggest that the mree enriched pattern reflects the contribution of mree enriched fecal phosphate the initial mree enrichment mechanism may have been analogous to that in which some modern algae preferentially extract mree from water of marine composition the mree enric ed signature may be preserved only in phosphate nodules that formed where terrigenous input was so low that it did not mask the characteristic fecal pattern rare ce depletion patterns reflect a primary seawater ree source that has not been obscured by fecal or detrital components

an improved method for extracting marine sediment fractions and its application to sr and nd isotopic analysis the radiogenic isotopic composition of both detrital and fe mn fractions in marine sediments can be used in paleoceanography to infer changes of bottom water circulation we have examined various chemical techniques for the analysis of sr and nd isotope ratios in these fractions and present a robust method that can be used to separate both the fe mn oxides and the detrital fraction from a marine sediment sample for isotopic analysis our sequential leaching procedure involves the use of 10 acetic acid followed by 1 m hydroxylamine hydrochloride in 25 acetic acid to remove the carbonate component and the fe mn oxide fraction respectively the applicability of our chemical procedure is illustrated with examples from a marine sediment core raised from the northern cape basin southeast atlantic ocean

role of alternating redox conditions in the formation of organic rich interval in the middle devonian marcellus shale appalachian basin usa abstract geochemical isotopic and petrographic analyses were performed on a 30 m core of the marcellus shale obtained from greene county pennsylvania to understand the dominant controls on organic matter deposition in the black shale study units our study suggests that the regeneration of nutrients such as nitrogen n and phosphorous p may have played a key role in the formation of organic carbon oc rich intervals in the marcellus shale the decomposition of organic matter is likely to have released n and p into the water column and the episodic upward mixing of these nutrient enriched waters enhanced primary production the ratios of corg nbulk and corg ptot are significantly higher in the oc rich zone of the core i e defined as toc 4 and located between 2393 and 2406 5 m depth the high corg ptot and corg nbulk ratios of the preserved organic matter may reflect the release of n and p by microbial processes indicating the recycling of nutrients during deposition of the oc rich interval in addition our data show a positive relationships between the corg ptot and corg nbulk ratios and the organic carbon content which indicate that the recycled nutrients may have promoted primary productivity resulting in higher oc accumulation in some intervals the geochemical and stable isotopic results also suggest that the alternating redox conditions in the water mass were favorable for nutrient regeneration highly variable trace metal concentrations e g u mo and v in the oc rich zone and a wide range of 15n and 34spyr values towards the top of the oc rich zone suggest fluctuations between anoxic and suboxic water conditions finally sedimentary features and agglutinated benthic foraminifera in the oc rich zone support the existence of short term fluctuations between suboxic and anoxic conditions near the sediment water interface multiple lines of evidence suggest that nutrient regeneration due to alternating redox conditions may have played an important role in the formation of oc rich intervals in the marcellus shale

geochemistry and mineralogy of rare earth elements in high phosphorus ooidal ironstones a case study of the kamysh burun deposit azov black sea iron province abstract this study is aimed at characterizing the distribution and speciation of the rare earth elements and yttrium ree y in ooidal ironstones from the kamysh burun deposit kerch peninsula with implications for the depositional environments and contributions of different ree y carriers to the ore budget the lower pliocene ooidal ironstone sequence of the so called kerch ores up to 15 m thick occupies an area of 28 km2 the ore sequence lies between miocene lower pliocene shell limestones and upper pliocene pleistocene sandy and clayey sediments and consists of horizontal ooidal ironstone beds composed mainly of goethite and x ray amorphous fe3 oxy hydroxides intercalated with siderite and or rhodochrosite beds iron is a main component in ooidal ironstones 50 03 66 19 wt fe2o3 and 1 61 wt feo as well as in fresh carbonate ores 34 wt feo and 14 70 wt fe2o3 the kerch ores contain up to 4 59 wt p2o5 and show significant positive correlation between p and fe r 0 75 the bulk ore samples and their coarse 1 10 mm fractions are goethite dominated and have similar phase major and trace element and ree compositions the fine la nd ca pr sm the ree content in fresh carbonate ores is below that in paas xav 103 ppm but approaches the latter in oxidized crusts xav 178 ppm the kerch ironstones also contain ree poor early diagenetic fe2 phosphate vivianite ree xav 0 93 ppm and ca fe2 phosphate anapaite ree xav 6 95 ppm with typical seawater ree y distributions the ooidal ironstones show mree enriched patterns with distinct negative y anomalies which reveals fe3 oxy hydroxides as chief carriers of adsorbed ree mainly mree the kerch ironstones accumulated ree progressively due to hysteretic dissolution and precipitation of fe3 oxy hydroxides in oscillating redox conditions the diagenetic source of ree stored in ooidal goethite ironstones was inferred from the paas normalized values cen cen vs nd and cen cen vs yn hon discrimination diagrams in general the ree y budget of the kerch ooidal ironstones mainly formed during early diagenesis and scavenging from pore water with a minor contribution of siliciclastic inputs in the absence of hydrothermalism

patterns of coherent decadal and interdecadal climate signals in the pacific basin during the 20th century two distinct low frequency fluctuations are suggested from a joint frequency domain analysis of the pacific ocean 30 s 60 n sea surface temperature sst and sea level pressure slp the lowest frequency signal reveals a spatially coherent interdecadal evolution in phase sst and slp anomalies are found along the subarctic frontal zone safz it is symmetric about the equator with tropical sst anomalies peaking near 15 latitudes in the eastern pacific the other low frequency signal reveals a spatially coherent decadal evolution it is primarily a low latitude phenomenon tropical sst anomalies peak in the central equatorial ocean with evidence of atmospheric teleconnections these interdecadal and decadal signals join the enso and quasi biennial signals in determining dominant patterns of pacific ocean natural climate variability relative phasing and location of the sst and slp anomalies for the decadal enso and the quasi biennial signals are similar to one another but significantly different from that of the interdecadal signal

enso like interdecadal variability 1900 93 a number of recent studies have reported an enso like eof mode in the global sea surface temperature sst field whose time variability is marked by an abrupt change toward a warmer tropical eastern pacific and a colder extratropical central north pacific in 1976 77 the present study compares this pattern with the structure of the interannual variability associated with the enso cycle and documents its time history back to 1900 the analysis is primarily based on the leading eofs of the sst anomaly and anomaly deviation fields in various domains and the associated expansion coefficient or principal component time series which are used to construct global regression maps of sst sea level pressure slp and a number of related variables the use of anomaly deviations i e departures of local sst anomalies from the concurrent global mean sst anomaly reduces the influence of global mean sst trends upon the structure of the eofs and their expansion coefficient time series an important auxiliary time series used in this study is a southern oscillation index based on marine surface observations by means of several different analysis techniques the time variability of the leading eof of the global sst field is separated into two components one identified with the enso cycle related variability on the interannual timescale and the other a linearly independent residual comprising all the interdecadal variability in the record the two components exhibit rather similar spatial signatures in the global sst slp and wind stress fields the sst signature in the residual variability is less equatorially confined in the eastern pacific and it is relatively more prominent over the extratropical north pacific the corresponding slp signature is also stronger over the extratropical north pacific and its counterpart in the cold season 500 mb height field more closely resembles the pna pattern the amplitude time series of the enso like pattern in the residual variability reflects the above mentioned shift in 1976 77 as well as a number of other prominent features including a shift of opposite polarity during the 1940s

rare earth elements in pore waters of marine sediments abstract the rare earth elements rees were measured in pore waters of the upper 25 cm of sediment from one site off peru and three sites on the california margin the pore water ree concentrations are higher than sea water and show systematic down core variations in both concentration and normalized pattern from these analyses and from comparison to other chemical species measured dissolved fe mn ba oxygen nitrate phosphate it is suggested that pore water rees can be grouped into three categories those that are from an fe source those that are from a poc source and cerium oxide rees from the fe source appear where anoxia is reached they have a distinctive middle ree mree enriched pattern the concentrations in this source are so elevated that they dominate ree trends in the fe oxide reduction zone the net result of flux from the poc source is relative enrichment of heavy rees hrees over light rees lrees reflecting remineralizing poc and complexation with doc a common linear ree pattern seen in both oxic and anoxic sediments is associated with this poc source as well as a hree enriched pattern that is seen in surficial sediments at the peru site overall the pore water results indicate that mn oxides are not an important carrier of rees in the oceans a ree biogeochemical model is presented which attempts to reconcile ree behavior in the water and sediment columns of the oceans the model proposes that poc fe oxide and ce oxide sources can explain the ree concentration profiles and relative abundance patterns in environments ranging from oxic sea water to anoxic pore water the model is also consistent with our observation that the ce anomaly of pore water does not exceed unity under any redox condition

a delayed action oscillator shared by biennial interannual and decadal signals in the pacific basin 1 biennial interannual and decadal signals in the pacific basin are observed to share patterns and evolution in covarying sea surface temperature sst 18 c isotherm depth z18 zonal surface wind zsw and wind stress curl wsc anomalies from 1955 to 1999 each signal has warm sst anomalies propagating slowly eastward along the equator generating westerly zsw anomalies in their wake these westerly zsw anomalies produce cyclonic wsc anomalies off the equator which pump baroclinic rossby waves in the western central tropical north pacific ocean these rossby waves propagate westward taking 6 12 and 36 months to reach the western boundary near 7 n 12 n and 18 n on biennial interannual and decadal period scales respectively there they reflect as equatorial coupled waves propagating slowly eastward in covarying sst z18 and zsw anomalies taking 6 12 and 24 months to reach the central eastern equatorial ocean these equatorial coupled waves produce a delayed negative feedback to the warm sst anomalies there the decrease in rossby wave phase speed with latitude the increase in meridional scale of equatorial sst anomalies with period scale and the associated increase in latitude of rossby wave forcing are consistent with the delayed action oscillator dao model used to explain el nino however this is not true of the western boundary reflection of rossby waves into slow equatorial coupled waves this requires modification of the extant dao model we construct a modified dao model demonstrating how the various mechanisms and the size and sources of their delays yield the resulting frequency of each signal

diagenetic uptake of rare earth elements by bioapatite with an example from lower triassic conodonts of south china abstract the distribution patterns of rare earth elements rees are frequently used as proxies for ancient seawater chemistry or paleomarine environmental conditions however recent work has shown that diagenesis can lead to remobilization and inter elemental fractionation of rees and that these effects often occur in conjunction with redox reactions in sediment porewaters here we review existing literature on the diagenetic fluxes of rees in marine sediments and porewaters in order to systematize existing knowledge on this subject rees undergo significant redistribution among sediment phases during both early and late diagenesis as a consequence of adsorption and desorption processes remobilization of rees commonly leads to inter elemental fractionation variously leading to enrichment or depletion of the light middle or heavy ree fractions further ree remobilization can be facilitated by redox changes e g through reductive dissolution of host phases in suboxic and anoxic porewaters characteristic ree distribution patterns develop through these processes 1 a flat distribution signifying predominantly terrigenous siliciclastic influence 2 a middle ree bulge probably due to adsorption of light and heavy rees to mn and fe oxyhydroxides respectively and 3 heavy ree enrichment indicative of hydrogenous seawater influence note all patterns in this paper are normalized to the ree composition of average upper continental crust or ucc in the second part of this study we undertake an analysis of the ree distributions in conodonts and whole rock samples from west pingdingshan a permian triassic boundary section in south china using ree th and y ho ratios we show that almost all of the conodont samples have a strong diagenetic overprint and that the hydrogenous ree fraction is small and not isolatable furthermore the conodonts contain two diagenetic ree components one characterized by low ree 100 300 ppm high ree th ratios 1000 strong middle ree enrichment and eu eu ratios of 1 5 2 0 and the second by high ree 300 2000 ppm low ree th ratios 20 30 little or no middle ree enrichment and eu eu ratios of 1 0 the first component exhibits a pronounced middle ree bulge that represents an early diagenetic signature associated with suboxic conditions possibly related to adsorption of rees onto fe mn oxyhydroxides in the shallow subsurface environment the second component shows a flat ree distribution that is similar to both our whole rock samples and average ucc indicating derivation from rees released from detrital siliciclastics e g clay minerals probably at a range of burial depths from shallow to deep failure of the conodont samples to yield an isolatable hydrogenous component demonstrates that bioapatite does not always preserve a primary marine ree signature given that bioapatite rees have been widely used for this purpose often on the assumption of minimal or no diagenetic influence our findings are likely to necessitate a re evaluation of the results of many earlier studies in general we counsel caution in inferring a hydrogenous origin for rees in bioapatite owing to frequent diagenetic alteration of ree distributions

slow instabilities in tropical ocean basin global atmosphere models abstract the effect of ocean boundaries on instability in coupled ocean natmosphere models is determined eigenvalues and eigenvectors are calculated for coupled systems featuring an ocean basin bounded zonally by a flat continent the atmosphere is periodic zonally about the globe the oceanic and atmospheric dynamics are both represented by linear shallow water equations on the equatorial plane the calculation involves latitudinal series expansion and longitudinal finite differencing certain of the modes i e eigenvectors have amplitudes that grow with time the growth being a direct result of the ocean atmosphere coupling comparison is made to modes previously determined for the theoretically simpler case where the ocean is zonally unbounded growing modes in the bounded ocean case correspond in aspects of behavior and structure to particular modes of appropriate wavelength in the unbounded ocean basin the basic mechanism of instability is the same in both cases growing modes in the bounded o

the controls on the major and trace element variation of shales siltstones and sandstones of pennsylvanian permian age from uplifted continental blocks in colorado to platform sediment in kansas usa shales siltstones and sandstones of pennsylvanian permian age from near the source in colorado to those in the platform in eastern colorado and kansas have been analyzed for major elements and a number of trace elements including the rees the near source sandstones are significantly more enriched student t test at better than the 99 confidence level in sio2 and na2o concentrations and more depleted in al2o3 fe2o3 total tio2 th hf sc cr cs rees y and ni concentrations and laco and lani ratios than the near source shales and siltstones most likely due to more plagioclase and quartz and less clay minerals in the sandstones than in the shales and siltstones there are no significant differences in k2o and sr concentrations and eueu lalu lase thsc thco and crth ratios between the near source sandstones and the near source shales and siltstones samples of the molas hermosa and cutler formations near the source that were formed in different environments in the same area contain no significant difference in eueu lalu lasc thsc thco and crth ratios so a generally silicic source and not the environment of deposition was most important in producing these elemental ratios for example crth ratios of near source shales siltstones and sandstones range from 2 5 to 17 5 and eueu range from 0 48 to 0 78 which are in the range of sources of sediments derived from mainly silicic and not basic sources near source shales and siltstones contain significantly higher student t test and more varied concentrations of most elements al2o3 fe2o3 mno tio2 ba th hf ta co sc rees nb y but significantly lower concentrations of na2o and eueu than platform shales and siltstones in kansas e g la 65 7 40 and eueu 0 55 0 07 in near source shales and siltstones and la 23 7 8 7 and eueu 0 64 0 08 in platform shales and siltstones the sio2 and cao concentrations are not significantly different in platform shales and siltstones compared to the near source shales and siltstones so dilution of other minerals by quartz and calcite is not the main reason for the lower concentration of most elements in the platform relative to the near source shales and siltstones rather the lesser concentrations of most elements in clay minerals of the platform shales and siltstones can account for the lower concentration of most elements compared to corresponding near source shales and siltstones the lower concentrations of many elements in clay minerals in the platform shales and siltstones may be a result of having been derived from recycling of clay minerals from older rocks the greater homogeneity of elemental concentrations of the platform shales and siltstones compared to those in the source is also consistent with homogeneous mixing of such recycled material also there is no significant difference in thsc laco thco lani and crth ratios of the near source sedimentary rocks in colorado to the platform shales and siltstones in kansas and the latter are also consistent with derivation from mostly silicic source rocks

authigenic apatite formation and burial in sediments from non upwelling continental margin environments abstract evidence for precipitation of authigenic carbonate fluorapatite cfa in long island sound and mississippi delta sediments suggests that formation of cfa is not restricted to environments of active coastal upwelling we present porewater data suggestive of cfa formation in both these areas application of a sequential leaching procedure designed specifically to separate authigenic carbonate fluorapatite from other phosphorus containing phases including detrital apatite of igneous or metamorphic origin provides strong supporting evidence for authigenic apatite formation in these sediments the size of the authigenic apatite reservoir increases with depth indicating continued formation of cfa during early diagenesis this depth increase is mirrored by a decrease in solid phase organic p at both sites suggesting that cfa is forming at the expense of organic p mass balance considerations application of diagenetic models to interstitial water nutrient data and the saturation state of the interstitial water are consistent with this interpretation diagenetic redistribution of phosphorus among the different solid phase reservoirs is observed at both sites and results in near perfect retention of p by these sediments over the depth intervals sampled formation of cfa in continental margins which do not conform to the classically defined regions of phosphorite formation renders cfa a quantitatively more important sink than has previously been recognized including this reservoir as a newly identified sink for reactive p in the ocean the residence time of p in the modern ocean must be revised downward the implication for ancient oceans of cfa formation in continental margin sediments other than phosphorites is that phosphorite formation may be less a representation of episodicity in removal of reactive p from the oceans than of localized concentration of cfa in phosphatic sediments by secondary physical processes

elemental mobility in phosphatic shales during concretion growth and implications for provenance analysis shale normalized rare earth element ree patterns record variable redox conditions in coprolitic phosphorite concretions and their host shales from the pennsylvanian age cyclothems in the u s midwestern states of oklahoma kansas nebraska iowa and ohio as well as the mississippian age fayetteville shale of arkansas shale normalized enrichments in middle ree mree developed as the phosphatic concretions lithified under reducing conditions in pore waters of organic rich muds depletions in mree sm ho in host shales correspond to the mree enrichments in some nearby concretions rare and weak negative cerium depletions in both reworked and unreworked phosphorite concretions suggest exposure to oxygenated waters positive europium anomalies in thick phosphorite coatings on coprolitic phosphorite concretion cores suggest extreme reduction during lithification of the phosphorite coating flat ree patterns in both host shales and phosphorite concretions probably reflect detrital influence phosphate diagenesis can affect the trace element chemistry of black shale enough to alter provenance signals overall enrichment in ree in phosphorite relative to host shale suggests movement of ree as does the mree enriched phosphorite near the mree depleted host shale diagenetically mobile ree can affect la th sc relationships used in provenance analysis the extent of the diagenetic modification of la th sc distribution is related to the amount of p2o5 present typical la th sc distribution in host shale results when p2o5 values are below 0 5 high la abundance substantially skews la th sc distribution when p2o5 is above 5 0 but when p2o5 is between 0 5 and 5 0 the extent of the effect is unclear oxides of aluminum and other major elements may be useful in recording detrital influence and proximity to the shoreline in phosphorite concretions most of the concretions nearest to shoreline sources of detrital input have both flat ree patterns and elevated values of al2o3 al2o3 fe2o3

processes of short term climatic variability in the baroclinic structure of the interior western tropical north pacific abstract a realistic simulation of short term climatic variability in the relative dynamic height of the interior western tropical north pacific 4 22 n 127 e 180 for 9 years 1966 74 was conducted using a two layer wind driven baroclinic long wave model results of this model were compared with bimonthly maps of observed dynamic height 0 400 db for the region constructed by white and hasunuma from all available temperature depth observations for the same period the interannual rms differences about the mean annual cycle of the model dynamic height had a spatial pattern over the region of interest that was nearly identical to that observed with maximum values i e 3 5 and 4 5 dyn cm respectively in the vicinity of the north equatorial ridge at 15 n and minimum values i e 2 0 and 3 5 dyn cm respectively in the vicinity of the north equatorial ridge at 15 n and minimum values i e 2 0 and 3 5 dyn cm respectively in the countercurrent trough at 7 n model frequency spectra were ident

a global el nino southern oscillation wave in surface temperature and pressure and its interdecadal modulation from 1900 to 1997 zonal wavenumber frequency spectra of sea surface temperature sst anomalies along the equator in the indo pacific basin for the 98 years from 1900 to 1997 and of surface temperature st and sea level pressure slp anomalies extending around the globe along 10 n for the 48 years from 1950 to 1997 display significant peak spectral energy density for standing and eastward propagating waves of 3 7 year periods and 120 360 zonal wavelengths the global standing wave is the familiar southern oscillation but the global propagating wave represents a new paradigm for the el nino southern oscillation enso global distributions of the phase velocities for this global enso wave finds covarying slp and st anomalies propagating eastward along the mean path of the intertropical convergence zone itcz with the global zonal wavenumber 1 2 component taking 4 6 years to cross the tropical indian pacific and atlantic oceans at a zonal average speed of 90 60 longitude per year along this path the interannual sst and slp anomalies are directly out of phase since thermocline depth anomalies underneath the itcz in the pacific ocean propagate westward white et al 1985 we view the global enso wave as a slow coupled sst wave trapped onto the itcz separating the global enso wave from the southern oscillation using complex empirical orthogonal function analysis finds the amplitude of the propagating wave to be half that of the standing wave with the former latter accounting for one third two thirds of the interannual variability in nino 3 sst and slp indices during the 1980s the global enso wave is shown to be responsible for the eastward propagation of covarying zonal surface wind and thermocline depth anomalies across the equatorial pacific ocean and through this mechanism is able to influence both the phasing and intensity of el nino examining the persistence of the global enso wave from 1900 to 1997 finds it and the intensity of el nino in the eastern equatorial pacific ocean modulated by interdecadal change both were strong weak or absent during decades of global tropical cooling warming

sequential extraction and analysis of phosphorus in marine sediments streamlining of the sedex procedure we streamlined the five step sedex sedimentary extraction procedure for characterizing sedimentary phosphorus to a four step procedure we combined extraction of adsorbed and oxide associated pools into a single step retaining steps for authigenic detrital and organic p in addition we used automated spectrophotometric flow injection analysis fia to determine p concentrations rather than traditional spectrophotometric techniques we decreased our total extraction and analytical time from 12 d for 24 replicate samples to 5 d without sacrificing our geo chemical objectives detection limits or analytical reproducibility

rare earth elements in authigenic methane seep carbonates as tracers for fluid composition during early diagenesis abstract authigenic carbonates forming at an active methane seep on the makran accretionary prism mainly consist of aragonite in the form of microcrystalline cryptocrystalline and botryoidal phases the 13 c carbonate values are very negative 49 0 to 44 0 v pdb agreeing with microbial methane as dominant carbon source the 18 o carbonate values are exclusively positive 3 0 to 4 5 v pdb and indicate precipitation in equilibrium with seawater at bottom water temperatures the content of rare earth elements and yttrium ree y determined by laser ablation inductively coupled plasma mass spectrometry la icp ms and solution icp ms varies for each aragonite variety with early microcrystalline aragonite yielding the highest cryptocrystalline aragonite intermediate and later botryoidal aragonite the lowest ree y concentrations shale normalised ree y patterns of different types of authigenic carbonate reflect distinct pore fluid compositions during precipitation microcrystalline aragonite shows high contents of middle rare earth elements mree reflecting ree patterns ascribed to anoxic pore water cryptocrystalline aragonite exhibits a seawater like ree y pattern at elevated total ree y concentrations indicating higher concentrations of rees in pore waters which were influenced by seawater botryoidal aragonite is characterised by seawater like ree y patterns at initial growth stages followed by an increase of light rare earth elements lree with advancing crystal growth reflecting changing pore fluid composition during precipitation of this cement conventional sample preparation involving micro drilling of carbonate phases and subsequent solution icp ms does not allow to recognise such subtle changes in the ree y composition of individual carbonate phases to be able to reconstruct the evolution of pore water composition during early diagenesis an analytical approach is required that allows to track the changing elemental composition in a paragenetic sequence as well as in individual phases high resolution analysis of seep carbonates from the makran accretionary prism by la icp ms reveals that pore fluid composition not only evolved in the course of the formation of different phases but also changed during the precipitation of individual phases

sr ca and mg ca ratios in niger delta sediments implications for authigenic carbonate genesis in cold seep environments we report on a reconnaissance analysis of the geochemical composition of authigenic carbonates and sediment samples collected from various seepage sites on the niger deep sea fan our aim has been to investigate whether evidence for the presence of authigenic carbonates and gas hydrates within sediments is discernible from solid phase sediment geochemistry we show that sedimentary sr ca and mg ca ratios can be used to infer the presence of authigenic aragonite sr rich and mg rich carbonate phases high mg calcite dolomite in cold seep settings using sr ca and mg ca ratios the proportion wt of authigenic carbonates in niger fan sediments can be calculated from a mixing model between sediment fractions of terrigenous material biogenic calcite aragonite and high mg calcite this approach was applied to high resolution geochemical profiles along sediment cores recovered from various cold seep settings mud volcano diapirs pockmarks gas hydrate bearing sediments our data reveal that authigenic carbonates occur as discrete phases in sediments from gas hydrate bearing areas suggesting that such carbonate rich sediment layers may represent paleo indicators for ancient methane seepage in marine sediments possibly associated to gas hydrate reservoirs

tropical coupled rossby waves in the pacific ocean atmosphere system abstract gridded fields of topex poseidon sea level height slh and national centers for environmental prediction sea surface temperature sst and meridional surface wind msw anomalies are constructed monthly on a 2 grid over the pacific ocean for nearly 6 years from 1993 to 1998 time longitude diagrams of monthly slh sst and msw anomalies from 10 to 22 lat yield significant peak spectral energy density in zonal wavenumber frequency spectra for periods of 1 2 yr near the free rossby wave dispersion curve subsequently temporal and spatial filtering of these slh sst and msw anomalies finds them propagating westward over the interior tropical pacific ocean in fixed phase with one another significant squared coherence exists between filtered slh and sst sst and msw anomalies over the entire latitude band yielding significant phase differences ranging over 90 45 70 45 at 10 s and 14 lat and ranging over 90 45 0 45 at 18 and 22 lat over the entire latitude domain warm

rare earth element cycling in the pore waters of the bering sea slope iodp exp 323 abstract we studied the diagenetic behavior of rare earth elements rees in a highly productive passive margin setting of the bering sea slope site u1345 was drilled during the integrated ocean drilling program expedition 323 at a water depth of 1008 m currently in the center of an oxygen minimum zone pore water concentrations of fourteen rees were determined down to 140 meters below the seafloor mbsf the ree concentrations were higher in the pore water than the deep seawater indicating that there was significant liberation from the sediments during diagenesis there was a major peak at 10 mbsf that was more pronounced for the heavy ree hree this peak occurred below the sulfate methane transition zone 6 3 mbsf and coincided with high concentrations of dissolved iron and manganese at 2 mbsf there was a minor peak in ree and mn contents below 40 mbsf the ree concentration profiles remained constant the ce anomaly was insignificant and relatively constant paas normalized ce ce 1 1 0 2 throughout the depth profile showing that the ce depleted in seawater was restored in the pore water hree enrichment was observed over the entire 140 m except for the upper 1 m where a middle ree mree bulge was apparent ree release in shallow depths 2 4 mbsf is attributed to the release of light rees lrees and mrees during the organoclastic reduction of mn oxides in anoxic sediments the high hree concentrations observed at 10 mbsf can be attributed to the reduction of fe and mn minerals tied to anaerobic oxidation of methane or less significantly to ferromagnesian silicate mineral weathering the upward diffusion flux across the sediment water interface was between 3 for tm and 290 for ce pmol m 2 y 1

off equatorial westward propagating rossby waves in the tropical pacific during the 1982 83 and 1986 87 enso events abstract analysis of anomalous vertically averaged temperatures tav in the tropical pacific ocean for the eight year period 1979 86 finds the development during the onset phase one to two years before the mature phase of the two enso events of the period having dynamically significant similarities both north and south of the equator during the onset phase of both enso events each beginning in the off equatorial western tropical pacific about 10 latitude positive anomalies of tav occurred during northern autumn winter one year prior to the mature phase of each enso event in both northern and southern hemispheres this corroborates model results of pazan et al and supports the hindcasting forecasting capability of enso events obtained by white et al though the latter considered only the northern hemisphere it is also demonstrated that the development of positive tav anomalies in northern autumn winter along the tropical maritime western boundary of both hemispheres was associated with wind

the early toarcian jurassic anoxic event stratigraphic sedimentary and geochemical evidence detailed paleogeographic studies in the southern alps suggest that an oxygen minimum model is appropriate for interpreting conditions on tethyan continental margins advection of manganese in this low oxygen layer may explain the local occurrence of carbonate ores of this element carbon sulfur and iron sulfur ratios although showing considerable scatter suggest that bottom waters at this time were locally euxinic containing free hydrogen sulfide this oceanic anoxic event was preceded by significant faunal turnover of ammonites in tethys and accompanied by widespread extinction of benthos in northern europe in response to the lateral spread of anoxic bottom waters during transgression similar changes may be recognized in other parts of the world other anoxic events may have taken place during the jurassic but documentation is as yet meagre furthermore models for such phenomena remain largely speculative although upwelling and increased planktonic productivity commencing in pre toarcian time are favored for the falciferum zone event documented here from author

organic geochemistry of the woodford shale southeastern oklahoma how variable can shales be woodford shale samples obtained from a cored outcrop in southeastern oklahoma were geochemically analyzed to determine vertical variations of organic facies thermal maturity and an evaluation of their depositional environments total organic carbon values ranged from 5 01 to 14 81 indicating a good source rock potential in this area the woodford shale is marginally mature as indicated by vitrinite reflectance values rock eval data revealed that the samples are dominated by type ii kerogen biomarker ratios based on pristane phytane steranes and hopanes show a mix of marine and terrigenous organic matter high salinity conditions and water density stratification also prevailed during deposition of this formation as indicated by the presence of gammacerane the woodford shale was subdivided into lower middle and upper members based on the integration of geochemical and geologic data moreover the presence and extent of photic zone anoxia pza were determined by the presence of aryl isoprenoids the lower and upper woodford shale members were deposited under dysoxic to suboxic conditions and episodic periods of pza the middle member was deposited under anoxic conditions and persistent pza in addition aryl isoprenoids helped infer the position of the chemocline during deposition of the different members the relative hydrocarbon potential parameter was used in determining transgressive and regressive cycles within the woodford shale this study undoubtedly demonstrates the significant lithologic and chemical variability that occurs within shales the application of this workflow to regional studies can have a direct influence on exploration and production activities in shale gas systems

benthic phosphorus regeneration net primary production and ocean anoxia a model of the coupled marine biogeochemical cycles of carbon and phosphorus we examine the relationships between ocean ventilation primary production water column anoxia and benthic regeneration of phosphorus using a mass balance model of the coupled marine biogeochemical cycles of carbon c and phosphorus p the elemental cycles are coupled via the redfield c p ratio of marine phytoplankton and the c p ratio of organic matter preserved in marine sediments the model assumes that on geologic timescales net primary production in the oceans is limited by the upwelling of dissolved phosphorus to the photic zone the model incorporates the dependence on bottom water oxygenation of the regeneration of nutrient phosphorus from particulate matter deposited at the water sediment interface evidence from marine and lacustrine settings modern and ancient demonstrates that sedimentary burial of phosphorus associated with organic matter and ferric oxyhydroxides decreases when bottom water anoxia dysoxia expands steady state simulations show that a reduction in the rate of thermohaline circulation or a decrease of the oxygen content of downwelling water masses intensifies water column anoxia dysoxia and at the same time increases surface water productivity the first effect reflects the declining supply of oxygen to the deeper parts of the ocean the second effect is caused by the enhanced benthic regeneration of phosphorus from organic matter and ferric oxyhydroxides sedimentary burial of organic carbon and authigenic calcium phosphate mineral francolite on the other hand is promoted by reduced ocean ventilation according to the model global scale anoxia dysoxia leads to a more efficient recycling of reactive phosphorus within the ocean system consequently higher rates of primary production and organic carbon burial can be achieved even when the continental supply of reactive phosphorus to the oceans remains unchanged

hindcast forecast of enso events based upon the redistribution of observed and model heat content in the western tropical pacific 1964 86 anomalous sea level anomalous observed dynamic height 0 400 db and anomalous model dynamic height are examined at the locations of 13 island sea level stations in the tropical pacific for each bimonth of the four year period 1979 to 1982 starting in 1981 the anomalous dynamic height data show off equatorial rossby waves propagated toward the w boundary of the pacific basin at the w boundary the model rossby wave activity was found to have excited coastally trapped kelvin munk waves which transmitted the anomalous dynamic height equatorward at the equator coastally trapped wave activity excited eastward propagating equatorial kelvin waves yielding a pair of anomalous peaks in dynamic height variability in the e equatorial pacific associated with the 1982 1983 enso event the evolution of the peaks in dynamic height associated with the rossby and kelvin wave activity reflects the redistribution of observed upper ocean heat content in the w tropical pacific providing a qualitative hindcast for the 1982 1983 enso event

high resolution geochemistry and sequence stratigraphy of the hushpuckney shale swope formation eastern kansas implications for climato environmental dynamics of the late pennsylvanian midcontinent seaway abstract the hushpuckney shale member of the swope formation missourian stage eastern kansas is the core shale of a kansas type cyclothem formed during the late transgressive to early regressive phases of a late pennsylvanian glacio eustatic cycle coeval high frequency climato environmental dynamics of the midcontinent seaway are preserved in the kgs orville edmonds no 1a study core as centimeter scale variation in major components organic carbon authigenic sulfides and phosphate detrital siliciclastics organic macerals trace element redox proxies mo u v zn and ichnofabric features benthic o 2 levels declined sharply from the base of the black shale 0 cm went sulfidic at 4 cm and reached a redox minimum at 21 cm above this level redox potential gradually rose fluctuating between sulfidic and nonsulfidic conditions from 35 cm to the black shale gray shale contact at 52 cm onset of dysoxic conditions at that contact allowed establishment of a benthic community of soft bodied organisms comprised of deep tiered tracemakers tolerant of low o 2 conditions trichichnus and shallow tiered tracemakers favoring soupground helminthopsis or firmground substrates the zoophycos phycosiphon schaubcylindrichnus planolites association most geochemical records exhibit a low order cycle spanning the full 52 cm thickness of the black shale submember reflecting a dominant glacio eustatic control the base and top of the black shale submember record lateral migration of the pycnocline across the midcontinent shelf during the transgressive and regressive phases respectively the maximum flooding surface mfs is at 17 23 cm an interval containing the euxinic peak and characterized by high concentrations of illite representing a cratonic siliciclastic flux and terrestrial organic macerals the product of transient increases in humidity weathering rates and the export of coal swamp vegetation associated with the interglacial highstand of the swope cyclothem although a transgressive surface of maximum starvation sms cannot be confidently identified a phosphate rich regressive condensation surface at 28 34 cm records pycnoclinal weakening due to increased aridity associated with renewed southern hemisphere icesheet growth a correlative shift in dominance from terrestrial to marine derived organic macerals reflects increased upwelling of nutrient rich deepwaters and enhanced primary productivity penecontemporaneous paleogeographic and climatic factors e g semirestricted circulation monsoonal precipitation predisposed the midcontinent seaway toward sensitivity to high frequency climato environmental fluctuations which are preserved as 2 to 7 cm thick cycles in the study core the 52 cm thick black shale submember contains 12 such high order cycles which have an estimated average duration of 2 to 9 kyr implying a sub milankovitch band i e millennial scale climatic control the results of this study are relevant to the sequence stratigraphic interpretation of kansas type cyclothems the dynamics of gondwanan ice age glacio eustatic cycles and the development of boundary conditions for late pennsylvanian paleoclimate models

controls on rare earth element distributions in ancient organic rich sedimentary sequences role of post depositional diagenesis of phosphorus phases abstract the processes that dictate the formation and preservation of rare earth element ree signatures in ancient marine black shales are incompletely understood thus potentially limiting the utility of the rees as geochemical tracers here we report on whole rock ree analyses of six black shale formations from different ages and depositional settings which fall within three general groupings group 1 is characterized by low whole rock ree content ree n la n n la n n la n 2 yb n la n 250 g g and moderately middle ree enriched patterns gd n la n 1 5 2 5 yb n la n 1 representative samples from these groups were selected from the marcellus and hushpuckney shales and subjected to a multi step leaching procedure to isolate four extractable p phases reducible authigenic carbonate associated detrital apatite organic in group 1 samples with low carbonate content 3 rees were hosted mainly in the organic 50 of ree and siliciclastic fractions 37 whereas in samples with greater carbonate content 25 caco 3 rees were hosted mainly in carbonate associated phases 53 in group 2 rees were hosted mainly in the carbonate associated 64 and organic fractions 30 and in group 3 rees were hosted mainly in the carbonate associated 60 detrital apatite 23 and siliciclastic fractions 16 authigenic phases include minerals such as carbonate fluorapatite and authigenic calcite that if present tend to dominate the whole rock ree inventory in the absence of carbonate whole rock ree content depends on the relative ree contributions of the organic and siliciclastic fractions

defining the nature and location of a late devonian early mississippian pycnocline in eastern kentucky the pycnocline the intermediate layer in a tripartite density stratified water column is an important element in recent explanations of the origin of anaerobic sediments dysaerobic sediments deposited where the pycnocline intersects the bottom are distinct from overlying aerobic and underlying anaerobic sediments and were used to define the position of the paleopycnocline on a late devonian early mississippian sea bottom in eastern kentucky surface and subsurface mapping of the bedford berea sequence and equivalent parts of the new albany and chattanooga shales reveals approximately coeval aerobic dysaerobic and anaerobic facies that permitted mapping of the paleopycnocline apparently the first time the actual sea bottom position of a paleopycnocline has been defined the bedford berea devonian mississippian sequence is situated between the black ohio shale devonian below and the black sunbury shale mississippian above the black shales reflect deposition in a deepening transgressive sea where anaerobic conditions were easily established and maintained the intervening bedford berea sequence however represents deposition in aerobic and dysaerobic environments during a shallowing regressive episode as deltas prograded to the south and west in eastern kentucky the gray sandstones siltstones and shales of the bedford berea sequence have been interpreted as pinching out between the black shales above and below in east central kentucky each of the above units however has a distinctive signature on gamma ray logs comparison of gamma ray logs and radioactivity profiles with corresponding cores drillers9 logs and exposures indicates that black shale equivalents are present beyond the point where the gray bedford shale pinches out this also is supported by limited biostratigraphic data this transition from gray bedford shales to black shale equivalents marks the approximate position of the ancient pycnocline and has been mapped in the subsurface and on the outcrop in eastern kentucky the ancient pycnocline closely parallels the bedford berea delta front suggesting major control by the delta the continued influx of oxygen rich sediment laden waters from the delta apparently prevented the northward and eastward migration of the pycnocline up the delta front the introduced oxygen and sediment however were effective only in breaking up the pycnocline over a distance of 25 to 40 km from the active delta fronts stratigraphic paleontologic and geographic constraints indicate that the paleopycnocline was not horizontal but sloped northeastward from shallower waters near the cincinnati arch to deeper waters off the delta fronts

basinal restriction black shales re os dating and the early toarcian jurassic oceanic anoxic event 1 profiles of mo total organic carbon toc through the lower toarcian black shales of the cleveland basin yorkshire united kingdom and the posidonia shale of germany and switzerland reveal water mass restriction during the interval from late tenuicostatum zone times to early bifrons zone times times which include that of the putative early toarcian oceanic anoxic event the degree of restriction is revealed by crossplots of mo and toc concentrations for the cleveland basin which define two linear arrays with regression slopes ppm of 0 5 and 17 the slope of 0 5 applies to sediment from the upper semicelatum and exaratum subzones this value which is one tenth of that for modern sediments from the black sea mo toc regression slope 4 5 reveals that water mass restriction during this interval was around 10 times more severe than in the modern black sea the renewal frequency of the water mass was between 4 and 40 ka the mo toc regression slope of 17 applies to the overlying falciferum and commune subzones the value shows that restriction in this interval was less severe and that the renewal frequency of the water mass was between 10 and 130 years the more restricted of the two intervals has been termed the early toarcian oceanic anoxic event but is shown to be an event caused by basin restriction local to nw europe crossplots of re os and mo against toc show similar trends of increasing element concentration with increase in toc but with differing slopes together with modeling of 187 os 188 os and d 98 mo the element toc trends show that drawdown of re os and mo was essentially complete during upper semicelatum and exaratum subzone times mo toc regression slope of 0 5 drawdown sensitized the restricted water mass to isotopic change forced by freshwater mixing so that continental inputs of re os and mo via a low salinity surface layer created isotopic excursions of up to 1 3 in d 98 mo and up to 0 6 for 187 os 188 os restriction thereby compromises attempts to date toarcian black shales and possibly all black shales using re os chronology and introduces a confounding influence in the attempts to use d 98 mo and initial 187 os 188 os for palaeo oceanographic interpretation

early diagenesis of organic matter in peru continental margin sediments phosphorite precipitation abstract pore water chemistry total dissolved co 2 nh 4 no 3 no 2 po 4 si oh 4 ca mg fe mn so 4 h 2 s and f and titration alkalinity solid phase chemistry c org p org c tot n tot f si opal and s ii and sediment characteristics porosity dry bulk density and formation factors were determined on a centimeter scale spacing in the upper 20 40 cm of sediments under intense upwelling areas on the peru continental shelf these data demonstrate that carbonate fluorapatite cfa is precipitating from pore waters in the upper few centimeters of a gelatinous mud with high organic carbon content up to 20 c org very high porosity 0 96 ml cm 3 and very low dry bulk density 3 dissolved phosphate concentrations at the sediment water interface range from 20 to 100 m orders of magnitude higher than bottom water concentrations and much higher than predicted from regeneration of organic matter the mechanism of this interfacial phosphate release is unclear but is apparently uncoupled from carbon and nitrogen metabolism and thus may be linked either to dissolution of fish debris or to the presence of a microbial mat in surficial sediments fluoride is incorporated into cfa by diffusion from the overlying seawater and carbonate ions are provided from pore water alkalinity magnesium concentrations in this reaction zone are not significantly different from those of seawater suggesting that magnesium depletion is not a necessary prerequisite for cfa precipitation the environment of precipitation is interface linked rather than driven by organic diagenesis of phosphorus deeper in the sediment most of the cores display a wide range of diagenetic characteristics below the immediate interfacial region but almost all show the precipitation signature near the interface this interface linked early diagenetic porewater environment for the precipitation of cfa explains many of the geochemical characteristics of phosphorites and provides a testable model to compare the modern phosphogenic analog with ancient phosphorite deposits two of the cores display very high solid phase phosphorus and fluoride contents reflecting the presence of apparently modern pelletal apatites

rare earth elements as tracers for microbial activity and early diagenesis a new perspective from carbonate cements of ancient methane seep deposits abstract ancient methane seep carbonates are geological archives of environmental conditions and record past microbial activity to better understand the information stored in this archive a comparison was made of phase specific major trace and rare earth element ree patterns mineralogies and textures of two early diagenetic carbonate phases in five ancient methane seep deposits including oligocene limestones from the satsop and canyon rivers washington state the cretaceous tepee buttes colorado and the carboniferous ganigobis limestones namibia 1 cryptocrystalline yellow aragonite and 2 banded and botryoidal aggregates of clear fibrous aragonite typify many phanerozoic seep limestones and are common features of authigenic seep carbonates forming close to the sediment water interface today light ree enrichment in yellow aragonite is observed together with high organic matter contents indicated by intense autofluorescence of yellow aragonite and occurs in combination with low mg sr ratios conversely heavy ree enrichment is observed in neomorphic yellow calcite spar typified by high mg sr ratios indicating progressive diagenetic alteration during early diagenesis in marine pore waters affected by a succession of biogeochemical reactions these observations suggest that ree contents and patterns of early diagenetic carbonate phases are a function of the quality of preservation transformation of primary aragonite to calcite resulting from changing pore water compositions during later stage early diagenesis is apparently capable to significantly modify elemental composition the new results reveal that rare earth elements do not necessarily behave conservatively if early diagenesis is controlled to a large extent by evolving pore water compositions in environments strongly affected by biogeochemical processes for such settings a careful assessment of diagenetic alteration is consequently required before calcite resulting from aragonite transformation can be used for reliable paleoenvironment reconstruction