conditions of formation and diagenetic evolution of upper proterozoic phosphate nodules from southern sweden evidence from petrology mineral chemistry and isotopes abstract dark gray to black cryptocrystalline francolite occurs as nodules 2 8 cm in diameter which are embedded in organic matter rich mudstones of the visingso group upper proterozoic southern sweden the 13cpdb values 18 4 to 0 98 of structural co2 complemented by studies of the petrographic character and strontium isotopic composition of francolite indicate precipitation in the suboxic and sulfate reduction zones francolite is intergrown with berthierine that has formed in the suboxic fe reduction zone calcite enriched in mn and to a lesser extent fe occurs as fracture and void fillings and as replacement of francolite mn and mg rich calcian siderites have precipitated as pseudomorphs after bacteria in the zone of microbial methanogenesis the carbon 13 c pdb 0 75 to 7 04 and oxygen 18 o pdb 14 21 to 10 58 isotopes of calcite suggest derivation of carbonate ions from microbial methanogenesis and from thermal decarboxylation of organic matter at temperatures of 60 to 80 c some of the void and fracture filling calcites 13 c 20 8 to 18 63 18 o 5 46 to 5 21 have however precipitated at lower temperatures 25 30 c in the sulfate reduction zone

highly variable coastal deformation in the 2016 mw7 8 kaikōura earthquake reflects rupture complexity along a transpressional plate boundary abstract coseismic coastal deformation is often used to understand slip on offshore faults in large earthquakes but in the 2016 m w 7 8 kaik ura earthquake multiple faults ruptured across and sub parallel to the coastline along 110 km of coastline a rich dataset of coastal deformation comprising airborne lidar differencing field surveying and satellite geodesy reveals highly variable vertical displacements ranging from 2 5 to 6 5 m these inform a refined slip model for the kaik ura earthquake which incorporates changes to the slip on offshore faults and inclusion of an offshore reverse crustal fault that accounts for broad low amplitude uplift centered on kaik ura peninsula the exceptional detail afforded by differential lidar and the high variability in coastal deformation combine to form the highest resolution and most complex record of coseismic coastal deformation yet documented this should prompt reassessment of coastal paleoseismic records that may not have considered multi fault ruptures and high complexity deformation fields

rare earth geochemistry of old phosphorites and probability of syngenetic precipitation and accumulation of phosphate1in memory of richard p sheldon1 abstract old vendian early cambrian phosphorites of the world demonstrate seawater like patterns in their rare earth element ree distributions but are depleted in heavy ree they also show a broad range of variation in total and elemental abundances primary bedded structureless phosphorites contain only 15 ppm total ree ree while granular pelletal varieties contain up to 650 ppm ree were incorporated into phosphate grains diagenetically during prolonged periods of transport and redeposition a higher surface mass ratio in pelletal phosphorites contributed to their enrichment in the ree s in primary bedded structureless phosphorites immediate burial of phosphate syngenetically precipitated and accumulated in situ at the sediment water interface prevented the later incorporation of the ree large deposits of vendian early cambrian phosphorites have originated by both processes primary bedded varieties occur in deeper water facies and granular phosphorites accumulated closer to the shore in terms of their ree geochemistry old granular phosphorites are almost indistinguishable from their phanerozoic counterparts indicating that both were deposited by the same mechanisms primary bedded structureless phosphorites were only deposited on a large scale at the beginning of the phanerozoic

carbon to phosphorus ratios in sediments implications for nutrient cycling defining the transformations of phosphorus p in sediments is critical to assessing the geochemical behavior of sedimentary p and the behavior of reactive p preactive poxide associated pauthigenic porganic relative to organic carbon corganic this study includes the determination of p components and corganic concentrations on samples from sites in the california current region ocean drilling program odp leg 167 sites 1010 1011 1012 1014 1016 and 1021 in the benguela current region odp leg 175 sites 1082 1084 and 1085 and on blake nose in the western atlantic odp leg 17 1b sites 1050 and 1052 sample depths range up to 650 m and ages range up to 65 ma our data demonstrate the transformation of labile forms of p porganic and poxide associated to pauthigenic throughout the sediment column in all redox states and at all sedimentation rates investigated until a substantial portion of reactive p is in the authigenic form 80 c p organic ratios are always greater than or equal to the redfield ratio in all of the sediments we studied sediments with corganic concentrations 2 wt have corganic preactive ratios less than the redfield ratio and corganic preactive ratios increase linearly with corganic consistent with degradation of corganic with age in general corganic preactive ratios for sediments with corganic concentrations 2 wt from a variety of redox states and sedimentation rates center around the redfield ratio although some ratios are as high as 3 times the redfield ratio however corganic preactive ratios up to 400 do not approach the high ratios observed for c p organic ratios up to 4500 because of the efficient transfer of labile forms of p to pauthigenic corganic preactive ratios better describe the geochemical behavior of sedimentary p

diagenetic evolution of the upper devonian phosphorites alborz mountain range northern iran abstract the upper devonian mixed siliciclastic carbonate stratigraphic succession of the geirud formation in the alborz mountain range north of iran hosts numerous phosphorites and phosphatic rocks these phosphorites which represent one of the most globally important deposits in the devonian have gained little attention regarding their genesis and diagenetic evolution this study focuses mainly on the post depositional changes that occurred during shallow to deep burial diagenetic evolution and subaerial weathering of the geirud phosphorites the phosphorites consist of phosphatic massive mudclasts detritus rich lithoclasts bioclasts and bones formed by several stages of phosphogenesis and erosion reworking winnowing and condensation associated with famennian sea level changes the phosphatic clasts consist of early diagenetic poorly crystalline carbonate fluorapatite cfa and pyrite cementing detrital quartz illite muscovite rutile and zircon phosphatic clasts are intensely compacted with sutured grain contacts along which dissolution and reprecipitation of chemically refined well crystalline cfa with a bright blue cathodoluminescence and illite occurred during deep burial diagenesis similarly quartz shows deformation planar features overgrowth cement was developed as a result of pressure dissolution in phosphatic sandstones followed by precipitation of ferroan dolomite ankerite and chlorite in secondary porosity subaerial weathering led to oxidation of pyrite and generation of acidic ph condition under which ca and p from phosphates fe and s from pyrite fe ca mg and mn from ferroan carbonates and al and si from aluminosilicates were released to form goethite psilomelane calcite gypsum and crandallite the paas normalized rare earth elements rees show bell shaped patterns with middle rees enrichment positive eu anomaly and a weak negative ce anomaly this implies recrystallization of cfa in phosphorites and phosphatic rocks during deep burial diagenesis deviating from the modern seawater like ree patterns in this regard deep burial diagenesis affecting the upper devonian geirud phosphorites is possibly a common process in the proterozoic paleozoic phosphorites in northern iran and elsewhere in the world

application of the ce anomaly as a paleoredox indicator the ground rules much attention has been paid in recent years to the potential application of the ce anomaly measured in various marine phases as a paleoceanographic indicator of widespread marine anoxia in this paper we present and discuss results from recent studies of present day rare earth element ree distributions and hence ce anomaly distributions in the marine environment which are particularly pertinent to paleoceanography subsequently we review and discuss the validity of the recent literature in which ce anomalies have been employed as paleoredox indicators

rare earth element and sr nd isotope geochemistry of phosphatic rocks in neoproterozoic ediacaran doushantuo formation in zhangcunping section from western hubei province south china abstract phosphatic rocks are widely distributed in neoproterozoic ediacaran doushantuo formation in yangtze platform south china in this study we examined samples from the zhangcunping section in western hubei province with major element rare earth element ree and sr nd isotopic analyses on the phosphorites and the host dolostone rocks we employed an acid leaching method to separate the carbonate acetic acid leachable and phosphate hydrochloric acid leachable fractions in all the samples the geochemical differences between the different fractions can be recognized based on the p2o5 ree contents and sr nd isotopic characteristics the carbonate fractions in the rocks display low total ree concentrations with seawater like ree patterns super chondritic y ho ratios moderate negative ce anomalies and positive eu anomalies indicating these carbonates have retained the signatures of paleo seawater on the contrary the phosphate fractions display high total ree concentrations with hat shaped ree patterns generally lower y ho ratios weak negative ce anomalies and positive eu anomalies which may have recorded the features of diagenetic fluids negative ce anomalies and positive eu anomalies displayed in the carbonate fractions of the studied samples may also indicate the anoxic environments of ocean basins in south china during the deposition of the neoproterozoic ediacaran doushantuo formation a geochemical comparison between lower phosphorite layer and upper phosphorite layer indicates a greater degree of diagenesis occurred in the lower phosphorite layer than the upper phosphorite layer the negative end t values of the samples suggest continental crustal sources for the rees and the lower values in the phosphorite samples 6 9 to 6 0 than the dolostone samples 5 5 to 3 8 may suggest different processes for them and it is likely that the rees in the phosphorites have been modified by diagenetic fluids with ree contributions of pore fluids derived from the clastic silicates in the strata which generally have lower end t values whereas the dolostone took the rees from the ambient seawater mainly

identification of primary ce anomaly signatures in fossil biogenic apatite implication for the cambrian oceanic anoxia and phosphogenesis based on ree analyses of 105 world wide distributed cambrian fossil apatite samples and eight late neoproterozoic phosphate concretions a close relationship is established between the concentrations of mree and ce anomalies shale la smn ratios of 0 35 is suggested as a critical value for the discrimination of the natural ce anomaly acquired during pre burial early diagenesis by biogenic apatite from an artificial ce anomaly induced due to the calculation ce anomalies in apatites with flat ree distribution and la smn ratio 0 35 may be used as indicative of oceanic anoxia

rare earth element and srnd isotope geochemistry of phosphate nodules from the lower cambrian niutitang formation nw hunan province south china abstract phosphate nodules are widely distributed in the early cambrian black shale sequence in yangtze platform south china in this study we carried out x ray diffraction major element rare earth element and sr nd isotopic studies on phosphate nodules from two pc c sections in hunan province south china two different types of phosphate nodules can be recognized based on ree and nd isotopic characteristics type 1 with seawater like ree patterns higher end t values and type 2 with hat shaped ree patterns and more negative end t values we suggest that the difference in ree patterns and nd isotopic compositions between the two types reflects changes in pore water geochemistry from seawater dominated towards diagenetic fluid dominated conditions during early diagenesis positive eu anomalies are displayed in most samples and are likely to record not only the anoxic environments but also the involvement of submarine exhalative hydrothermal fluids which prevailed in south china during early cambrian

radiometric dates of uplifted marine fauna in greece implications for the interpretation of recent earthquake and tectonic histories using lithophagid dates n ad 365 a great mw n 8 earthquake lifted up western crete exposing a shoreline encrusted by marine organisms and up to 10 m of marine substrate beneath it radiocarbon ages determined for corals and bryozoans exposed between the paleo shoreline and present sea level are consistent within measurement error with each other and with the date of the earthquake but radiocarbon ages determined for the boring bivalve lithophaga lithophaga found on the same substrate are at least 350 years and up to 2000 years older than the date of the earthquake that lifted them above sea level these observations reveal two important effects that limit the use of radiocarbon lithophagid ages in tectonic and paleoseismological studies the first is that the exceptional preservation potential of lithophagids allows them to remain intact and in situ long after natural death while the substrate continues to be colonised until eventual uplift the second which we confirm with radiocarbon analysis of museum specimens of known age is the incorporation of old 14c free carbon into lithophagid shells from the limestone host rock into which the lithophagids bored the two effects are both significant in crete and central greece and can cause the radiocarbon lithophagid ages to be up to 2000 years older than the uplift event which exposed them understanding these effects is important because lithophagids are far more abundantly preserved and used to date uplift than most other marine organisms this study shows that they can rarely be used to distinguish uplift events or date them to better than 1000 years or even to distinguish whether observed uplift occurred in a single or in multiple events after taking account of these uncertainties the ages of the lithophagids are however consistent with the hypothesis that the highest prominent marine notches and exposed lithophagid holes within a few metres of sea level in greece formed when sea level became relatively stable 6000 years ago following rapid rise after the last glacial maximum

rise of the central andean coast by earthquakes straddling the moho coastlines above subduction zones often uplift over geological timescales analysis of landscape evolution and seismicity at the central andean margin suggests that earthquakes on the deep plate interface help build up coastal topography

what can a sessile mollusk tell about neotectonics article i nfo dendropoma petraeum are fixed vermitids mollusk that colonize and construct abrasion platform rims along rocky shorelines these endemic mollusks are considered good relative sea level indicators in the eastern and the southern mediterranean due to their narrow habitat below the sea surface about 10 cm the observed relative sea level values recorded submerged uplifted or at present mean sea level reflect a superposition of eustatic isostatic tectonic and possibly local sedimentary instabilities the present study examines fossil dendropoma samples gathered along the levant coast from northern israel to eastern turkey conventional radiocarbon dates from turkey syria and partly in lebanon and 14 c accelerator mass spectrometer ams from lebanon and israel yields dendropoma ages ranging through late holocene a numerical model is used for calculating the change in sea level through the holocene as a function of glacio hydrology and isostasy of the eastern mediterranean space time dependent subtractions of the model values are used to eliminate the eustatic component of the relative sea level in order to obtain the tectonic component results show a general northward increase in tectonic uplift of the levantine coast with different rates in different tectonic segments this differential uplift corresponds well to the major tectonic segments comprising the levantine continental margin since the pleistocene from the carmel fault to the east anatolian fault hence these segments were still active during the last thousands years and even during the last hundreds years the general trend of northward increase in vertical displacement is predominantly dictated by the convergence between the sinai and arabian plates with anatolia and eurasia across the cyprus arc and zagros belt and the secondarily dictated by the northward increase in convergence component across the sinistral dead sea fault plate boundary

rare earth elements and stable isotope geochemistry of early cambrian chert phosphorite assemblages from the lower tal formation of the krol belt lesser himalaya india abstract the neoproterozoic cambrian transitional sequence in the mussoorie and garhwal hills of the lesser himalaya is represented by dolomites of the upper krol formation and chert phosphorite assemblages of the lowermost tal formation these rocks provide valuable information regarding the assumed existence of a stratified ocean during the terminal neoproterozoic and beginning of earliest cambrian nemakit daldynian the isotopic compositions of carbonate and organic carbon in the transition profile can be best interpreted as reflecting an oceanic anoxic event oae prior to the phase of early cambrian phosphate formation the chert phosphorite beds record negative ce and positive eu anomalies while ce is an important paleooceanic redox indicator eu is rather immobile under normal diagenetic conditions the observed eu anomaly is linked to the high ba content in these phosphorites and is indicative of an anoxic or sulfate reducing diagenetic environment the suggested stratification of the ocean during the late neoproterozoic and nemakit daldynian times would have been linked to the reduction of oxygen supply to the zone below the redoxcline causing 12 c and p rich organic matter previously produced in the photic zone to be trapped in large quantities within the deeper anoxic zone this would in turn increase the 13 c content of the water in the photic zone moreover in the deeper anoxic waters reduction of ce4 to ce3 would result in an enrichment of dissolved ce as ce3 upwelling of this anoxic bottom stratum would bring the 12 c and ce enriched waters back to the oxic marine realm however on entering the highly oxic productive zone the excess ce is expected to be removed from the water by oxidation to insoluble ce4 followed by precipitation or preferential scavenging due to these oxidation reactions the waters of the shallow oxic zone would tend to become rapidly depleted in ce in other words ocean mixing and upwelling during the early cambrian were ultimately responsible for the transport of 12 c p and ce to the oxic shelves sharp drops in both 13 c carb and 13 c org support the existence of oceanic anoxia followed by oceanic mixing at this juncture of earth history the large spread of the 34 s values of early diagenetic pyrites within the phosphorite bearing sequence in contrast to the limited spread of 13 c carb values suggests that phosphatisation took place under exclusively suboxic diagenetic non sulfate reducing condition and pyritisation began only when phosphate layers entered the zone of sulfate reduction

surface modification on bone trampling versus butchery abstract previous researchers have reported difficulties in distinguishing between surface marks on bone formed by sedimentary abrasion and those inflicted while butchering trampling by large ungulates and humans has been credited with producing pseudocut marks natural alterations to the bone that mimic cultural ones the purposes of this research are 1 to re examine trampling as a taphonomic process and 2 to suggest criteria useful for distinguishing sedimentary abrasion including trampling from butchery macroscopic and microscopic comparison of experimentally trampled bones and those which have had soft tissue removed with a flint tool demonstrate significant differences between the surface modifications produced by the two processes

ree patterns in latest neoproterozoic early cambrian phosphate concretions and associated organic matter abstract analyses of ree were conducted on phosphatic concretions and various types of associated organic matter in eight key latest neoproterozoic earliest cambrian inner to outer shelf marine phosphatic successions that are distributed worldwide a pronounced ree fractionation during diagenetic degradation of the organic matter has been revealed selective mree incorporation and bulk ree contents in some kerogens organic megascopic fossils and humic acid are compatible with those recorded in associated phosphate the similarity of ree patterns in apatite and organic matter suggests that early diagenetic microbial decomposition of organic matter does not only provide phosphorus and suitable sub oxic geochemical conditions but it is also a likely source of ree enrichment in authigenic apatite formed at shallow depths below the marine water sediment interface

relative influences of the interdecadal pacific oscillation and enso on the south pacific convergence zone 1 the south pacific convergence zone spcz one of the most extensive features of the global atmospheric circulation is shown to vary its location according to both the polarity of the el nino southern oscillation enso and of the interdecadal pacific oscillation ipo we first demonstrate that the ipo can be regarded as the quasi symmetric pacific wide manifestation of the pacific decadal oscillation that has been described for the north pacific shifts in the position of the spcz related to enso on interannual time scales and to the ipo on decadal time scales appear to be of similar magnitude and are largely linearly independent a station pressure based index of variations in spcz latitude is shown to be significantly related to the polarity of the ipo when enso influences are accounted for movements of this sensitive section of the spcz have occurred in phase with those of the ipo since the 1890s

rare earth element geochemistry of late devonian reefal carbonates canning basin western australia confirmation of a seawater ree proxy in ancient limestones rare earth element and yttrium ree y concentrations were determined in 49 late devonian reefal carbonates from the lennard shelf canning basin western australia shale normalized sn ree y patterns of the late devonian samples display features consistent with the geochemistry of well oxygenated shallow seawater a variety of different ancient limestone components including microbialites some skeletal carbonates stromatoporoids and cements record seawater like ree y signatures contamination associated with phosphate fe oxides and shale was tested quantitatively and can be discounted as the source of the ree y patterns co occurring carbonate components that presumably precipitated from the same seawater have different relative ree concentrations but consistent ree y patterns clean devonian early marine cements n 3 display ree y signatures most like that of modern open ocean seawater and the highest y ho ratios e g 59 and greatest light ree lree depletion average nd sn yb sn 0 413 sd 0 076 however synsedimentary cements have the lowest ree concentrations e g 405 ppb non contaminated devonian microbialite samples containing a mixture of the calcimicrobe renalcis and micritic thrombolite aggregates in early marine cement n 11 have the highest relative ree concentrations of tested carbonates average total ree 11 3 ppm stromatoporoid skeletons unlike modern corals algae and molluscs also contain well developed seawater like ree patterns samples from an estuarine fringing reef have very different ree y patterns with lree enrichment nd sn yb sn 1 possibly reflecting inclusion of estuarine colloidal material that contained preferentially scavenged lree from a nearby riverine input source hence devonian limestones provide a proxy for marine ree geochemistry and allow the differentiation of co occurring water masses on the ancient lennard shelf although appropriate partition coefficients for quantification of devonian seawater ree concentrations from out data are unknown hypothetical devonian canning basin seawater ree patterns were obtained with coefficients derived from modern natural proxies and experimental values resulting devonian seawater patterns are slightly enriched in lree compared to most modem seawaters and suggest higher overall ree concentrations but are very similar to seawaters from regions with high terrigenous inputs our results suggest that most limestones should record important aspects of the ree geochemistry of the waters in which they precipitated provided they are relatively free of terrigenous contamination and major diagenetic alteration from fluids with high non seawater like ree contents hence we expect that many other ancient limestones will serve as seawater ree proxies and thereby provide information on paleoceanography paleogeography and geochemical evolution of the oceans copyright c 2004 elsevier ltd

diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies an isotopic and ree study of cambrian phosphorites seawater rare earth element ree distributions show heavy ree enrichment and cerium depletion but these characteristics are only rarely found in ancient marine authigenic minerals such as carbonate fluorapatite and calcite this enigma may be due to changing ree distributions in seawater through time or to post depositional redistribution of ree differentiating between these two factors is however far from straightforward as their relative importance is likely to vary and evidence is often ambiguous in this article we present ree as well as strontium and sulphur isotope data for basal cambrian phosphorites of south china which confirm the emerging rule of thumb that granular phosphorites seldom reveal extreme departures from the seawater norm and tend to undergo therefore less diagenetic alteration of ree spectra than skeletal apatites and other phosphate types this study reveals stratigraphic trends in ce anomalies ce ce that could be taken to imply the preservation of a palaeoenvironmental signal however further investigation of our data shows that such trends in phosphorites can also be caused by post depositional alteration which tends to 1 increase ree contents 2 reverse ce depletion 3 alter eu anomalies and 4 concentrate preferentially the middle ree mree further alteration which may be due to weathering has led to hree depletion and positive la and y anomalies tetrad effect this is the first study where ceanom and phosphate bound sulphate s isotope values could be compared for one particular stratigraphic section which provides us with an additional tool for the interpretation of diagenetic redox conditions least altered phosphorites from meishucun that yield a strongly negative ceanom constrain early cambrian seawater 34s to about 33 we conclude that phosphorite ceanom primarily records variations in the local conditions of diagenesis while outlining some special cases in which diagenetic redox conditions may broadly reflect local bottom water redox conditions

origin of the ediacaran weng an and kaiyang phosphorite deposits in the nanhua basin sw china abstract the weng an and kaiyang phosphorite deposits are located in central guizhou southwestern china and formed within the sinian ediacaran doushantuo formation a systematic investigation of the geology mineralogy and geochemistry of these phosphorites was conducted to constrain the redox environment origin and genetic mechanisms of ediacaran phosphorite in the lower ore layer layer a the phosphate minerals are mainly globular phosphate intraclasts which are characterized by special sedimentary and reworking textures including microgranular sedimentary isopachous cement shrinkage crack and spongy texture the phosphate minerals from the upper layer layer b have microbial phosphate components namely embryo and algae like microfossils these phosphatic microfossils have biological structures and both consist of interior structure and isopachous wall the p2o5 concentration of phosphorites in layer a reach 32 31 somewhat higher than that in layer b 28 7 whereas the p content in globular phosphate intraclasts 40 05 resemble that of the microbial phosphate component 41 19 rocks from layer a have left inclining post archean australian shale paas normalized rare earth element ree distributions with higher ce anomalies ceanom ranging from 0 12 to 0 01 average 0 07 in contrast rocks from layer b have hat shaped paas normalized ree distributions with lower ceanom ranging from 0 32 to 0 23 average 0 28 these geochemical characteristics suggest that hydrothermal fluids mixed with normal seawater might have contributed to metallogenesis and the redox environment transitioned from anoxic to oxic from layer a to b we conclude that the lower doushantuo globular intraclasts formed by the mechanical reworking of previous phosphatic sediments which were dominated by the strong mechanical power of seawater the upper doushantuo microbial phosphorite on the other hand formed by microbially mediated accretionary growth

formation of late quaternary paleoshorelines in crete eastern mediterranean abstract paleoshorelines of late quaternary age in western crete do not exclusively increase in age with rising altitude as is generally observed worldwide at numerous sites for example late holocene paleoshorelines decrease in age with increasing altitude while in other cases paleoshorelines at similar altitude vary in age by tens of thousands of years we propose that the observed paleoshoreline altitude age relationships can be accounted for by eustatic sea level changes and tectonic rock uplift without requiring substantial errors on radiocarbon ages or tectonic subsidence as has been previously proposed to test this model we use a dataset consisting of altitude and age data for 71 individual paleoshorelines sampled from 21 sites distributed along the entire cretan coastline these data include radiocarbon ages of marine biota 40 new dates within beachrock resting on paleoshorelines ranging up to 48 kyr bp in age and 20 m above present sea level we find that paleoshoreline formation reflects late holocene tectonic rock uplift in western crete preceded by eustatic sea level rise and by 10 kyr bp rock uplift along the entire island our observations contravene existing models as they suggest that some paleoshorelines and their associated lithified beachrock survived passage through the wave zone multiple times and formed throughout the sea level cycle i e preservation is not restricted to highstand deposits these results may have application globally in regions where erosion resistant carbonate beachrock mantles paleoshorelines

complex multifault rupture during the 2016 mw 7 8 kaikōura earthquake new zealand the 2016 moment magnitude m w 7 8 kaik ura earthquake was one of the largest ever to hit new zealand hamling et al show with a new slip model that it was an incredibly complex event unlike most earthquakes multiple faults ruptured to generate the ground shaking a remarkable 12 faults ruptured overall with the rupture jumping between faults located up to 15 km away from each other the earthquake should motivate rethinking of certain seismic hazard models which do not presently allow for this unusual complex rupture pattern science this issue p eaam7194 1 1 lookup doi 10 1126 science aam7194

rafting rocks reveal marine biological dispersal a case study using clasts from beach cast macroalgal holdfasts abstract tracking and quantifying biological dispersal presents a major challenge in marine systems most existing methods for measuring dispersal are limited by poor resolution and or high cost here we use geological data to quantify the frequency of long distance dispersal in detached bull kelp phaeophyceae durvillaea in southern new zealand geological resolution in this region is enhanced by the presence of a number of distinct and readily identifiable geological terranes we sampled 13 815 beach cast bull kelp plants across 130 km of coastline rocks were found attached to 2639 of the rafted plants and were assigned to specific geological terranes source regions to quantify dispersal frequencies and distances although the majority of kelp associated rock specimens were found to be locally derived a substantial number 4 showed clear geological evidence of long distance dispersal several having travelled over 200 km from their original source regions the proportion of local versus foreign clasts varied considerably between regions while short range dispersal clearly predominates long distance travel of detached bull kelp plants is shown to be a common and ongoing process that has potential to connect isolated coastal populations geological analyses represent a cost effective and powerful method for assigning large numbers of drifted macroalgae to their original source regions

holocene emergence in euboea island greece abstract detailed mapping along the northwestern coastline of euboea has provided new evidence of colonization by lithophaga lithophaga l reaching about 3 8 m above the present biological msl such marine biological marks together with morphological notches correspond to the occurrence of two sequences of holocene vertical displacements higher than those reported by previous studies on the central part of the southern coast and along the northern coast of the island a well developed emerged notch is found at 1 7 0 1 m above present mean sea level whereas the uppermost part of the lithophagid holes suggest a former emerged shoreline at least at 3 8 0 1 m radiocarbon ams dating of lithophaga shells found in their burrows showed that the lower uplifted shoreline corresponds to a tectonic event probably coseismic apparently dated at 2200 a bp while the higher shoreline corresponds to an older relative sea level transgression possibly of tectonic origin apparently dated about 5570 a bp the apparent radiocarbon age of lithophagid shells can be about 350 to 400 years older than the uplift event that exposed them due to incorporation of host rock carbon nevertheless the two new paleoshorelines provide evidence that repeated uplift movements greater than those reported by previous authors occurred during the late holocene uplifting the western part of the island

recurrent anoxia recorded in shallow marine facies at zhangcunping western hubei china throughout the ediacaran to earliest cambrian abstract in order to reconstruct the redox history of surface seawater for ediacaran shallow marine facies on the yangtze platform as well as to understand its implications for geological events oxidation and phosphatization and early evolution of life we have conducted a systematic high resolution investigation on microfacies analyses pyrite morphology as well as sulfur and carbon contents in a continuous carbonate ediacaran cambrian succession drilled 407 core in the zhangcunping area of western hubei south china the framboidal pyrites and snav toc nav non acid volatile sulfur based redox reconstruction show a dynamic history of recurrent shallow marine anoxia the early aftermath of the marinoan glaciation cap dolomite to phosphorites was characterized by either absence of pyrite or dominated by large framboids low toc contents and phosphorite deposition as well as well preserved microfossils indicating a minor oxygenated dysoxic to oxic photic shallow marine ecosystem meanwhile the uppermost doushantuo and dengying formations were potentially fully oxygenated due to the lack of pyrites as well as low snav and toc contents correlating with macrofossil assemblages miaohe biota and ediacara biota found in western hubei a major oxygenated marine ecosystem can be outlined for the late ediacaran in addition a complicated diagenetic microfabric overprints the fine microstructure of microfossils preserved in phosphorites leaving remarkable taphonomic puzzles for future study

a petrographic and geochemical study of carbonate and silica phases from the ediacaran doushantuo formation in the three gorges area of south china implications for diagenetic conditions abstract the carbonate of the ediacaran doushantuo formation contains various silica phases in the three gorges area of south china to better understand the diagenetic conditions under which these silica phases formed we carried out a petrographic and geochemical study of the silica phases and the coadjacent carbonate phases at the xiaofenghe section xfh in the three gorges area of south china five types of silica phases can be distinguished based on petrographic characteristics s1 and s2 are composed of microcrystalline quartz in chert nodules and disseminated in the host dolostone respectively s3 is composed of the megaquartz while s4 and s5 are microcrystalline quartz and fibrous silica respectively both replacing calcite cement six distinct types of carbonate can be recognized including the host matrix carbonate c1 sparry calcite nodules c2 calcite around chert nodules c3 dispersed calcite cement within chert nodules c4 fine micropeloidal calcite cements c5 and calcite veins c6 sedimentary structures suggest that formation of the s1 through s5 silica phases and c2 through c5 carbonate phases occurred during early burial diagenesis and therefore their formation recorded early diagenetic conditions assuming that ediacaran surface seawater temperature ranged from 28 to 39 c surface seawater 18o values can be calculated based on the oxygen isotopic composition of the host dolostone matrix c1 which range from 6 to 0 4 to 0 and 2 to 0 for the d2 d3 and d4 subunits of the doushantuo formation respectively based on the 18o values of chert nodules and beds mainly phase s1 diagenetic temperatures can be constrained to between 27 and 60 c under such low diagenetic temperatures the primary geochemical signatures of the host dolostone such as ree y patterns 13ccarb and 34spy values are likely to be preserved those silica phases without evidence of contamination of continental silicate detritus show characteristic ree y patterns with minor light ree depletions positive la eu and gd anomalies negative ce anomalies and slightly super chondritic y ho ratios implying that the source of silica may be derived from seawater negative ce anomalies in the silica phases in d2 through d4 subunits indicate that the bottom seawater or early diagenetic porewater was oxic at the time of silica precipitation

paleoredox variations in ancient oceans recorded by rare earth elements in fossil apatite abstract rare earth element concentrations in biogenic apatite of conodonts fish debris and inarticulate brachiopods were determined in over 200 samples from cambrian to modern sediments tests for experimental bias caused by the chemicals used to separate fossils from the rock matrix and for interlaboratory interexperiment or interspecies related variations clearly show that no resolvable fractionation of ree occurs incorporation of ree in biogenic apatite of recent fish debris occurs near the sediment water interface soon after deposition and reflects characteristics of seawater the original ree signature apparently survives subsequent burial and diagenesis cerium variations in fish debris from modern environments are controlled by redox potential ce is fractionated by co precipitation with metallic oxides under oxidizing conditions this fractionation produces a negative ce anomaly ce anom in seawater that is reflected in the sedimented fish debris conversely no fractionation of ce occurs under reducing conditions resulting in ce concentrations that are normal to enriched in anoxic seawater and fish debris deposited under local or basinwide anoxic conditions extrapolation of observations of the redox control of ce anom in modern oceans to fossil apatite indicates that anoxic conditions were prevalent in lower paleozoic and lower triassic oceans whereas in the upper paleozoic the world ocean was generally oxidizing

crystal chemical controls on rare earth element concentrations in fossil biogenic apatites and implications for paleoenvironmental reconstructions abstract fossil biogenic apatites display rare earth element ree patterns which have been proposed to reflect environmental and biological controls on past seawater composition these patterns can be separated in two groups 1 patterns that are similar to those of open ocean and epicontinental waters and 2 patterns that exhibit a strong enrichment in intermediate ree bell shaped patterns because ree trapping in biogenic apatites occurs mostly post mortem it is essential to understand the crystal chemical inorganic factors that can influence the fractionation of ree between apatite and water a model is proposed by which partition coefficients of ree between apatite and water for a substitution mechanism can be extrapolated from mineral melt partition data to seawater or sedimentary basin conditions these are compared with available experimental partition coefficients for ree adsorption mechanism and used to discuss ree patterns in fossil biogenic apatites calculations of ree patterns for apatites at equilibrium with water show that the bell shaped patterns in fossil apatites can be explained by fractionation with seawater or continental fluids at low temperature under crystal chemical control involving a substitution mechanism and in the context of extensive or late diagenesis in that case the equilibrium composition of the fluid cannot be unequivocally determined from observed ree concentrations in fossil apatites this type of sample is inappropriate to discuss the past environmental or biological controls on ree concentrations in the ocean other sample compositions suggest little to moderate alteration of the original oceanic to freshwater pattern through the adsorption mechanism in the context of weak or early diagenesis and may be used with caution for that purpose

sr and nd isotopic analysis of phosphorite sedimentation through one miocene high frequency depositional cycle on the north carolina continental shelf abstract a well developed seismic litho and biostratigraphic data base with good models for the formation and deposition of phosphate rich sediments exist for the upper cenozoic sediments on the north carolina continental margin this provides a unique opportunity to evaluate the potential of utilizing strontium and neodymium isotopic analyses to help unravel a complex genetic history of phosphate formation and deposition thirty one samples from three vibracores in onslow bay supplied hand picked concentrate subsamples of five phosphate grain types and thirty one concentrate subsamples of phosphate peloids for stratigraphic analysis all subsamples were analyzed for their sr isotope composition while only thirteen were analyzed for nd isotopes the 31 peloid samples represent three different stratigraphic units and include 1 holocene surficial sands with highly variable concentrations and types of reworked phosphate 2 pleistocene moldic carbonates with minor concentrations of black peloidal phosphate and 3 miocene mid burdigalian frying pan sequence unit 1 fps 1 of the pungo river formation with very high concentrations of multiple types of phosphate grains that decrease upsection and change grain types with changing lithofacies the latter unit represents deposition during one high frequency sea level cycle stratigraphic analysis utilized one grain type phosphate peloids for comparative purposes with the depositional model of riggs and mallette 1990 the sr and nd data cluster into significant categories that are coincident with these three major stratigraphic units sr and nd isotope compositions of selected phosphate grains from three phosphate rich depositional sequences are utilized to 1 date the initial miocene transgression of unit fps 1 of the pungo river formation 2 decipher processes of formation and deposition of major phosphate grain types through one miocene sea level cycle including the processes of in situ formation versus reworking 3 develop a sr and nd chronostratigraphy for evaluating changing patterns of continental margin sedimentation through high frequency depositional cycles 4 determine effects of reworking and weathering on the isotope signals between miocene pleistocene and holocene sediments 5 evaluate the suitability of utilizing sr and nd isotopes for detailed chronostratigraphic analysis of phosphorite sedimentation and 6 refine our understanding of the upper cenozoic evolutionary history of north carolina s continental margin

fossil preservation through phosphatization and silicification in the ediacaran doushantuo formation south china a comparative synthesis phosphatized and silicified microfossils preserved through replication of organic templates by authigenic calcium phosphate and silica respectively form through mechanistically similar mineralization processes but under notably different conditions in order to characterize the environments and taphonomic processes associated with these preservational pathways we compare phosphatized and silicified fossil assemblages in the ediacaran doushantuo formation south china in terms of stratigraphic and paleogeographic distribution preservation and biodiversity several differences are recognized 1 phosphatization and silicification both occurred in sub tidal doushantuo sediments but phosphatized fossils generally occur in shallower sub tidal facies than silicified fossils 2 although both phosphatized and silicified fossils are preserved three dimensionally the latter are typically more compressed and 3 whereas phosphatized assemblages are numerically dominated by multicellular acritarchs putative metazoan eggs and embryos silicified assemblages are dominated by prokaryotes these differences can be explained by environmental and taphonomic distinctions phosphatized fossils occur in intraclastic phosphorites and phosphatic carbonates and were likely fossilized near the suboxic anoxic boundary in sediments under oxic bottom waters with redox and biogeochemical gradients conducive to p remineralization phosphate burial via iron pumping and calcium phosphate precipitation reworking and winnowing of phosphatized fossils preferentially concentrated certain taxa prior to final burial in contrast silicified fossils typically occur in chert nodules which formed deeper in the sediment column in ferruginous pore waters and perhaps under ferruginous bottom waters where bacterial sulfate reduction and pyrite formation created low ph conditions conducive to calcite dissolution and silica precipitation once formed chert nodules mostly remained in situ but some were reworked with turbidites and olistostromes developed in slope facies despite these distinctions phosphatized and silicified fossil assemblages in the doushantuo formation generally overlap in time and space and representatives of all major groups and many common genera of doushantuo organisms are present in both phosphorites and cherts consequently although both preservational pathways have paleoenvironmental and taphonomic biases their relative biases on taxonomic presence absence data are minimal given sufficient sampling efforts and paleobiologic and biostratigraphic information based on presence absence but not abundance data from the doushantuo formation appears to be robust

geochemical characteristics of phosphorite and carbonate nodules from the miocene funakawa formation western margin of the yokote basin northeast japan abstract phosphorite nodules were discovered in diatomite and diatomaceous mudstones of the late miocene funakawa formation in dewa height on the western margin of the yokote basin northeast japan they occur as small nodules cemented burrows and small trace fossils in diatom rich sediment that was deposited just above the contact between underlying siliceous shales the underlying shales are essentially devoid of fossils and the overlying bioturbated diatomaceous mudstones are fossil rich the underlying shale is rich in manganese mn calcite nodules and the overlying mudstone is rich in magnesian mg calcite nodules some phosphorite nodules exhibit a zonal structure caused by two phases of mg calcite cementation with or without mn calcite within the pore space of the nodule the phosphorus p content of these nodules exceeded 25 wt in p2o5 the principle phosphate mineral composing the nodules is fluor f carbonate apatite crystals which are a few m in length and cocoon shaped their aggregate includes a small amount of silica aluminum and water si al and h2o respectively the rare earth element ree composition of the phosphorite nodules is characterized by a positive europium eu anomaly and no cerium ce anomaly the biomarker distribution of the phosphorite nodules is characterized by low cpi low carbon number n alkane and high hopenes type hopane and isoprenoid ketone phosphorite nodules originate from the phosphate contained in diatoms the mineralization occurs in the bacterial sulphate reduction zone and bacteria appear to have played an important role in the concentration of p and precipitation of apatite

miocene phosphorites from the murray ridge northwestern arabian sea abstract phosphorites from the murray ridge nw arabian sea comprise nodules bioclasts and bone fragments the nodules are made up of a homogeneous light colored phosphate nucleus consisting of rivulariacean filamentous cyanobacteria and a thin dark grey colored phosphate cortex showing abundant microbial filaments and microborings the bioclasts comprise of 14 14 5 ma old planktonic foraminifers accepted as the time of deposition spherical to ovoid shaped apatite microparticles resembling fossil bacteria are distinct components in the bioclasts bone fragments exhibit apatite fillings the nodules and bone fragments consist entirely of carbonate fluorapatite cfa with low al k and th concentrations suggesting absence of continental detritus shale normalized ree patterns of the samples support a seawater derived composition the highly uniform initial nd values of 4 8 to 5 1 are interpreted as the seawater value at the onset of phosphatization 14 ma ago in contrast 87sr 86sr ratios show a large range of 0 709055 to 0 709124 corresponding to unusually young stratigraphic ages of 1 to 3 ma the data are interpreted as evidence for post depositional sr exchange of the recrystallizing phosphorites with fluids isotopically not much different from modern seawater it is concluded that the phosphorites formed under oxic shallow water conditions where microbial populations assimilated phosphorus primarily from seawater and mediated precipitation of cfa during early diagenesis at the sediment water interface on different substrates

apatite nodules as an indicator of depositional environment and ore genesis for the mesoproterozoic broken hill type gamsberg zn pb deposit namaqua province south africa nodules consisting of fluorapatite are concentrated as a discrete band in the polymetallic sulfide ore of the gamsberg deposit in central bushmanland south africa their shape zonal features and geochemistry in particular rare earth element ree abundances are similar to authigenic francolite concretions that precipitate during diagenesis in organic rich muds as a result the apatite nodules are regarded as primary the nodules have a strong lithostratigraphic control occurring at the transition of siliciclastic hosted pyrite sphalerite graphite mineralization to calc silicate hosted pyrrhotite sphalerite mineralization mineralogical and chemical evidence indicates that this transition also corresponds to a paleo redox boundary that separates sediments deposited under oxygen deficient conditions from those that developed in a more oxygenated environment the apatite nodules can morphologically and chemically clearly be distinguished from coarse apatite grains that occur in oxide facies iron formations stratigraphically above the ore horizon however similar ree profiles and in particular positive eu anomalies in both types of apatite are indicative of a close genetic relationship between the two units and favor a common hydrothermal origin of the p the contrasting morphologies and chemical signatures of the two occurrences can rather be attributed to differences in behavior of the phosphates during precipitation within the contrasting host sediments chemical versus fine grained clastic taking modern phosphorites as an analogue these results are used to postulate a genetic model for the deposition of the sulfide ore and associated iron formations the model envisages differentiation of the depositional basin into oxygen deficient basin facies hosting the sulfide ore and oxygenated shelf facies which are composed of manganiferous iron formations the intimate association of sedimentary apatite with base metal sulfides indicates that basin conditions were conducive to the precipitation of both phases this relationship might act as a potential exploration guide in similar basins elsewhere

two major cenozoic episodes of phosphogenesis recorded in equatorial pacific seamount deposits seamount phosphorites have been recognized since the 1950s but this is the first study to provide an in depth exploration of the origin and history of these widespread deposits representative samples from equatorial pacific cretaceous seamounts were analyzed for chemical mineralogical and stable isotope compositions the phosphorites occur in a wide variety of forms but most commonly carbonate fluorapatite cfa replaced middle eocene and older carbonate sediment in a deep water environment 1000 m element ratios distinguish seamount phosphorites from continental margin plateau and insular phosphorites uranium and thorium contents are low and total rare earth element ree contents are generally high ree ratios and shale normalized patterns demonstrate that the rees and host cfa were derived from seawater strontium isotopic compositions compared with inferred cenozoic seawater curves define two major episodes of cenozoic phosphatization late eocene early oligocene 39 34 ma and late oligocene early miocene 27 21 ma three minor events are also indicated the major episodes occurred at times of climate transition the first from a nonglacial to glacial earth and the second from a predominantly glacial to warm earth the paleoceanographic conditions that existed at those times initiated and sustained development of phosphorite by accumulation of dissolved phosphorus in the deep sea during relatively stable climatic conditions when oceanic circulation was sluggish fluctuations in climate sealevel and upwelling that accompanied the climate transitions may have driven cycles of enrichment and depletion of the deep sea phosphorus reservoir as temperature gradients in the oceans increased antarctic glaciation expanded and oceanic circulation and upwelling intensified expansion and intensification of the oxygen minimum zone may have increased the capacity for midwater storage of phosphorus supplied by dynamic upwelling around seamounts however the bottom waters never became anoxic during the phosphogenic episodes fluctuations in the ccd and lysocline co2 fluxes and changes in bottom water circulation and temperatures may have bathed the seamount carbonates in more corrosive waters which coupled with increased supplies of dissolved phosphorus promoted replacement processes the late eocene early oligocene phosphogenic episode recorded in seamount deposits is not matched by large phosphorite deposits in the geologic record whereas the late oligocene early miocene episode and middle miocene event are matched by large deposits distributed globally the seamount phosphorites are exposed at the surface of the seamounts and have been for most of the neogene and oligocene the phosphorites do not show signs of etching that would indicate substantial undersaturation of seawater phosphate with respect to cfa mass balance calculations indicate that about 5 4 19 1012 g of p2o5 are locked up in equatorial pacific seamount phosphorites that amount is equivalent to about 2 7 years of the present annual input from rivers

cerium anomaly variations in ediacaran earliest cambrian carbonates from the yangtze gorges area south china implications for oxygenation of coeval shallow seawater abstract the late neoproterozoic ocean witnessed the naissance of animals which is believed to have been stimulated by an increase in oxygen levels in the ocean however apart from the emergence of animal fossils little supporting evidence has been found for the rise of oxygen in shallow seawater here we present ce anomaly data a redox proxy with a higher reduction potential than many other redox proxies for carbonates from well preserved marine successions the doushantuo formation dengying formation and lower yanjiahe formation of the ediacaran period and the upper yanjiahe formation of early cambrian on the neoproterozoic yangtze platform in the yangtze gorges area in order to constrain the redox evolution of the shallow marine environment calculated ce anomalies were screened using the following criteria al 36 in acetic acid leached carbonate to target samples that preserve primary seawater ree features and ce anomalies the samples satisfying this screening show seawater like ree distribution patterns in leached carbonates and may have recorded ce anomalies of the seawater from which the carbonates precipitated these data show that the doushantuo formation has ce ce values between 0 92 and 0 71 the dengying formation between 0 90 and 0 40 and the yanjiahe formation between 0 52 and 0 72 the ce ce values of the doushantuo formation suggest that shallow waters during the doushantuo stage 635 551 ma were anoxic to suboxic from the bottom to the top of the dengying formation ce ce values decrease systematically which cannot be explained by a change in depositional depth of the carbonate but suggests that the shallow waters became more oxygenated during the dengying stages from 551 ma to ediacaran cambrian boundary these results may provide direct evidence for an increase in oxygen levels in the shallow marine environment during the ediacaran period

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

kelp dna records late holocene paleoseismic uplift of coastline southeastern new zealand abstract holocene paleoseismic activity on the akatore fault zone southeastern new zealand has caused uplift of a 23 km section of coastline by several metres prominent relict shoreline terraces are preserved at 6 m and 3 m above the present sea level and the latter terrace was formed 1000 1400 yrs bp the main fault strand farther inland has 6 m of late holocene vertical offset but the relationships between coastal offsets and fault offsets are not understood there is no preserved geological evidence on the coastline to distinguish between incremental uplift e g numerous centimetre scale events and major metre scale uplift events a distinction that is important for evaluating regional paleoseismicity we have used genetic characterisation of populations of live kelp durvillaea antarctica growing along the shoreline to investigate whether or not there has been a catastrophic uplift event greater than the two metre tidal range that was sufficient to extirpate intertidal kelp populations our results show that all kelp along the southeastern new zealand coastline belongs to the same distinctive clade of d antarctica and inhabits the same ecological niches on exposed rocks and reefs however the kelp population on the uplifted coastline is genetically uniform and clearly distinct from those of flanking shorelines this regional genetic anomaly is consistent with a major extirpation event followed by recolonisation from source populations some 30 120 km to the northeast of the uplifted coast the uplift event caused vertical crustal movement with similar amounts of uplift on the fault plane and the coastline 3 km away this approach using genetics of intertidal biota has potential applications for evaluation of paleoseismicity of other tectonically active shorelines around the world

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

evidence for late quaternary episodic uplift of the sao pedro and sao paulo archipelago equatorial atlantic abstract the sao paulo and sao pedro archipelago spa forms an emergent part of the sao paulo transform fault zone in the equatorial atlantic in the present study the uplift rate of this part of the transform in the late quaternary was investigated in order to determine its origin uplift rates were determined by dating sedimentary and biological paleo sea level indicators the findings are a paleo sea level indicators yielded ages corresponding to the late pleistocene and mid to late holocene b ages between 43 6 and 18 9 ka correspond to paleo sea levels between 8 2 and 12 1 m above present sea level suggesting a maximum uplift rate of 3 3 2 9 and a minimum uplift rate of 0 8 1 2 mm y c the observation of a pleistocene megabalanus in the spa provides a new piece of information for understanding the evolution and biogeography of the genus d the ages of the holocene sea level indicators range between 6 2 ka and near present 13 3 m which are higher values than for mid to late holocene eustatic sea level suggesting strong uplift for that period and e different rates of lowering of sea level for the last 6 2 ka f ages and paleo sea level also suggest that almost instantaneous uplifts of 3 and 2 m could have occurred at approximately 2 5 and 0 2 ka g the rates of change in sea level indicate a clear pattern of episodic uplift which is typical of related coseismic movements in a stick slip mode h this scenario implies that the area could be affected by medium to large earthquakes mb 5 4 where a vertical displacement of 2 3 m could occur

rare earth element contents of jurassic fish and reptile teeth and their potential relation to seawater composition anglo paris basin france and england the rare earth element ree chemistry of jurassic shelf seawater from western europe anglo paris basin was investigated by analyzing the fish and reptile teeth deposited in shallow to deeper water 200 m environments ree patterns in apatites are controlled by the host sediments vertebrate teeth sampled from the siliciclastic sediments calcareous sandstones and shales show flat shale normalized ree patterns that reflect the dominant influence of the continental source from which the ree were derived carbonate deposits protected from the clastic sources contain fish and reptile teeth whose ree patterns reflect more accurately the ree composition of the overlying water column the ree patterns are similar through the bajocian to the oxfordian and are characterized by a depletion in heavy rare earth element dy ybn 1 8 5 0 compared to modern seawater compositions dy ybn 0 8 0 9 the fractionations among hree in the jurassic seawater are more efficient than in modern oceans and increases with depth instead of decreasing these hree removal processes operated as early as the paleozoic and disappeared during the late cretaceous the fractionation of hree relative to lree is correlated with the increasing depth of the basin as indicated by two independent criteria that are the sedimentary structures and the oxygen isotope composition of coexisting brachiopods the dy ybn ratio of the marine biogenic phosphates can be used as a proxy of paleo water depths at the scale of a water mass ce anomalies ce in biogenic apatite bearing limestones are variable and systematically negative relative to modern surface seawater and bathonian values mean ce 0 63 0 10 weak ce anomalies during the callovian mean ce 0 21 0 09 suggest the onset of more reducing conditions this redox change coincided with an increase of seawater temperatures as suggested by the oxygen isotope compositions measured on the same teeth we speculated that the callovian low ce could result from a decrease in the po2 due to the warming of seawater

removal of oceanic ree by authigenic precipitation of phosphatic minerals abstract early diagenetic phosphatic minerals containing rare earth elements ree are widespread in australian shallow marine sandstones of all ages most common is the aluminophosphate florencite ree al 3 po 4 2 oh 6 but the isomorphous and chemically intergrading phases crandallite gorceixite and goyazite all with up to several percent ree substituted for their major cation ca ba and sr respectively may also be present together they comprise up to 0 144 wt average 0 0134 wt of their host rocks the authigenic phosphates xenotime and apatite are also widespread but less common they all apparently precipitated within the diagenetic zones of sulphate reduction and methanogenesis as a result of reverse weathering reactions after the release of ree and po 4 by reduction of fe mn oxyhydroxides and the decomposition of organic material coating detrital particles as the aluminophosphates and apatite are enriched in light ree whereas xenotime concentrates heavy ree they collectively deposit light ree at a much greater rate la 129 10 9 g cm 2 yr 1 than heavy yb 0 40 10 9 g cm 2 yr 1 the total burial flux of light ree by shallow marine phosphatic precipitation is about 50 times greater than previously determined for deep sea sediments whereas heavy ree are buried at comparable rates this new sink produces a major imbalance in the marine ree budget requiring the existence of a substantial but currently unknown source to restore balance its size has important implications for the use of ree abundances distributions and isotopes as monitors of marine geochemical processes

rare earth geochemistry of phosphorites abstract the abundance of rare earth elements ree s in francolite increases with increasing age as a result of post depositional enrichment abundances are higher in pelletal samples than in non pelletal ones because the higher surface mass ratio of pelletal francolite promotes enrichment during diagenesis onshore francolite has higher ree abundances than that found offshore distribution patterns in francolite may be similar to those reported for open ocean water or shale depending upon the dominant source of the ree s different patterns result from weathering and deep burial diagenetic modification of the original patterns and abundances negative ce anomalies occur in francolites containing structural sulphur that is isotopically indistinguishable from seawater of the same age zero or positive anomalies occur in francolites which contain sulphur that is isotopically lighter than seawater

trace and rare earth element geochemistry of phosphate nodules from the lower cambrian black shale sequence in the mufu mountain of nanjing jiangsu province china abstract phosphate nodules are abundant in the lowermost section of the lower cambrian black shale sequence along a ne trend belt in the yangtze platform south china in this study we examined the neoproterozoic cambrian mufu mountain section near nanjing of jiangsu province and conducted a detailed trace and rare earth element ree study on the phosphate nodules we employed a step leaching acid dissolution protocol of 1 m hac and 1 m hcl respectively to separate carbonate from phosphate mineral contributions in the nodules both the hac leached and hcl leached fractions of the phosphate nodules show similar symmetrical variations in trace and ree concentrations and ratios the total rees and a number of redox sensitive trace metals such as v cr mo ni abundances show a systematic increase from the core to rim whereas the u and mn abundances decrease from the core to rim in most of the nodules similar trends are also observed for the rb sr u th co ni and v ni ratios but these trends in the hac leached fractions are less pronounced than the hcl leached fractions all of the hcl leached fractions for the nodule cores show seawater like shale normalized ree patterns but the rims of the nodules display slightly mree enriched and hree depleted patterns we suggest that the phosphate nodules may have formed in a basinal setting beneath a stratified water column during early cambrian and the compositional variations of rees and redox sensitive trace elements from the core to rim may record a changing redox condition and fluid mixing during different stages of nodule growth the cores of the nodules preserve more pronounced negative ce anomalies and progressively hree enriched patterns which may retain primary early cambrian seawater chemistry whereas the nodule rims record chemistry consistent with changed redox conditions and or influences from pore fluids such as generated from degradation of organic matter

preservation of seawater sr and nd isotopes in fossil fish teeth bad news and good news abstract we analyzed 87sr 86sr ratios in foraminifera pore fluids and fish teeth for samples ranging in age from eocene to pleistocene from four ocean drilling program sites distributed around the globe site 1090 in the cape basin of the southern ocean site 757 on the ninetyeast ridge in the indian ocean site 807 on the ontong java plateau in the western equatorial pacific and site 689 on the maud rise in the southern ocean sr isotopic ratios for dated foraminifera consistently plot on the global seawater sr isotope curve for sites 1090 757 and 807 sr isotopic values of the pore fluids are generally less radiogenic than contemporaneous seawater values as are values for fossil fish teeth in contrast pore fluid 87sr 86sr values at site 689 are more radiogenic than contemporaneous seawater and the corresponding fish teeth also record more radiogenic values thus sr isotopic values preserved in fossil fish teeth are consistently altered in the direction of the pore fluid values furthermore there is a correlation between the magnitude of the offset between the pore fluids and the seawater curve and the associated offset between the fish teeth and the seawater curve these data suggest that the hydroxyfluorapatite of the fossil fish teeth continues to recrystallize and exchange sr with its surroundings during burial and diagenesis therefore sr chemostratigraphy can be used to determine rough ages for fossil fish teeth in these cores but cannot be used to fine tune age models in contrast to the sr isotopic system our nd concentration data combined with published isotopic and rare earth element data suggest that fish teeth acquire nd during early diagenesis while they are still in direct contact with seawater the concentrations of nd acquired at this stage are extremely high relative to the concentrations in surrounding pore fluids as a result nd isotopes are not altered during burial and later diagenesis therefore fossil fish teeth from a variety of marine environments preserve a reliable and robust record of deep seawater nd isotopic compositions from the time of deposition

carbon isotope chemostratigraphy and sedimentary facies evolution of the ediacaran doushantuo formation in western hubei south china abstract the doushantuo formation of south china consisting of intercalated siliciclastic and carbonate rocks which exhibit considerable variation in thickness and sedimentary facies is one of the key sedimentary units in the world for understanding ediacaran geobiological processes however stratigraphic correlation and sedimentary facies evolution of the doushantuo formation remain controversial sedimentary facies analysis of the well known sections of the yangtze gorges area and new sections in northern yichang western hubei indicate that the doushantuo succession in the yangtze gorges area was deposited in an offshore intra shelf basin within the yangtze platform in contrast the doushantuo formation in the northern yichang area which is characterized by one or a few phosphate rich horizons represents deposition on the subtidal or intertidal shelf and so is similar to the succession in the weng an area central guizhou province the carbon isotope profiles of the different sections exhibit significant variation which is interpreted to result from facies differences sequence and high resolution carbon isotope stratigraphy have clarified problematic correlations and the temporal relationship between fossil assemblages of the doushantuo formation on the yangtze platform the results confirm that a prominent negative 13ccarb excursion baince nadir down to 5 in the middle portion of the second sequence of the doushantuo formation is a widely traceable event baince together with three other 13ccarb excursions namely cance at the base wance near the first sequence boundary near the middle and dounce at the top of the doushantuo formation constitute a complete carbon isotope profile for the doushantuo formation that reflects contemporaneous seawater and so serves as a reference chemostratigraphic profile for global stratigraphic correlation and for evaluating the chemical evolution of seawater during the ediacaran period

land level changes produced by the mw 8 8 2010 chilean earthquake we observed vertically displaced coastal and river markers after the 27 february 2010 chilean earthquake moment magnitude mw 8 8 land level changes range between 2 5 and 1 meters evident along an approximately 500 kilometers long segment identified here as the maximum length of coseismic rupture a hinge line located 120 kilometers from the trench separates uplifted areas to the west from subsided regions a simple elastic dislocation model fits these observations well model parameters give a similar seismic moment to seismological estimates and suggest that most of the plate convergence since the 1835 great earthquake was elastically stored and then released during this event

short paper lyell s pillars and uniformitarianism it is suggested that the roman pillars at pozzuoli near naples the great symbols of uniformitarianism record not gradual but very sudden changes in sea level and a more catastrophic or at least episodic concept of changes in the recent geological past than was envisaged by charles lyell the great symbols of uniformitarianism were the marine borings in the roman pillars of serapeo serapis at pozzuoli near naples charles lyell used the pillars as the frontispiece of his great book principles of geology 1831 which was to have such a fundamental effect on geological thought in the last century they also appear on the reverse side of the lyell medal of the geological society of london the importance of these pillars was that they proved that changes in sea level had occurred in historic times they were the proof it might be said that the present may be used as the key to the past if sea level changes could occur so recently then all the complex pattern of transgressions and regressions in the geological past could be explained by reference to what was seen happening today they put an end it was thought to catastrophism and the doctrine of sudden short lived episodes in earth history which was always associated with the thought of that great frenchman georges cuvier but the lyell and cuvier of standard text books are cardboard figures as stephen gould called them 1987 cuvier is particularly maligned and blamed for all the later excesses of catastrophism it

late holocene coseismic uplift on the hua tung coast eastern taiwan evidence from mass mortality of intertidal organisms abstract the evidence of coseismic uplift on the dynamic wave dominated hua tung coast fringing the active coastal range eastern taiwan has been equivocal due to complex controls by wave and terrestrial sediment over morphological and ecological systems of the coast this study by applying radiocarbon dating methods demonstrates coseismic uplift nature of the coast by finding synchronously killed intertidal organisms mostly boring shell jouannetia sp stranded at different sites of the coast with distinct physiographic characters based on these data together with evidence from wave cut notch sequences two coseismic uplift systems are recognized one centers around the northern middle part of the coast and yields events with uplift amounts of maximal 3 6 m and an average recurrence interval of at least several hundred years the most recent activity of this system influencing at least 70 km of coast occurred at 0 9 ka the earthquake generating this event also triggered extensive landslides debris flows in the region another system exemplified by the uplift associated with the 2003 cheng kung earthquake centers on the southern part of the coast and yields uplift of likely

trace and rare earth element geochemistry of black shale and kerogen in the early cambrian niutitang formation in guizhou province south china constraints for redox environments and origin of metal enrichments abstract early cambrian black shales of south china not only host important sponge arthropod and other soft bodied fossils that have helped to trace early metazoan diversification but also show extreme enrichments of a number of trace metals in particular ni mo and v in this study we use a new approach by analyzing rare earth elements in kerogen extracted from the black shales together with a number of redox sensitive trace element compositions and total organic carbon toc concentrations in an early cambrian black shale sequence in zunyi guizhou province south china to place better constraints on the oceanic redox conditions and the origin of the extreme metal enrichment our data show significant negative ce anomalies ce ce as low as 0 4 occurring in kerogen which indicate an oxygenated surface environment of primary productivity in consistent with the concept that the organic matter is mainly derived from organisms in the euphotic zone mass balance calculation suggests that the kerogen associated ree can dominate the measured black shale ree budget while similarity between our measured ree patterns and those of similarly aged phosphorites indicates that the ree content of ancient phosphorites may have also derived initially from organic matter the redox sensitive trace elements such as u v mo and their ratios of u al v al and mo al in black shales show different correlation patterns with toc contents the upper black shales show a good metal toc correlation but such a correlation is absent in the lower part the lower black shales exhibit much higher metal enrichments compared to black sea sulphidic euxinic sediment this is taken to indicate the presence of sulphidic bottom waters during the deposition of the lower black shales including the ni mo ore layer in contrast anoxic non sulphidic conditions occurred during the deposition of the upper black shales taking all these geochemical data together we suggest that the early cambrian south china seaway was strongly stratified and stagnant and that euxinic bottom water conditions may have led to enrichment of the redox sensitive metals such as u v and mo in the lower black shales and in one case the occurrence of a polymetallic ni mo sulphide ore bed bearing an extraordinarily extreme metal enrichment which according to the mo toc and ni toc ratios and much other geochemical evidence may have been additionally influenced by hydrothermal input of metals within the rift basin as suggested by a number of previous studies