spatial and temporal variation of geochemical properties and paleoceanographic implications in the south korea plateau east sea during the late quaternary geochemical opal total organic carbon toc and caco3 analyses of three sediment cores from the south korea plateau in the east sea japan sea revealed that the late quaternary 190 kyr bp to the present paleoceanographic conditions are characterized by the orbital variations of geochemical properties that have recorded the changes of surface and bottom water conditions chronostratigraphy of the sediment cores was accomplished by the direct correlation of l values to the well dated core md01 2407 in oki ridge supplement to the ams 14c dates well known lithostratigraphic and tephrostratigraphic markers biogenic opal concentrations are high during marine isotope stage mis 1 and mis 5 5 and low during the glacial period suggesting that diatom production was enhanced during the warm period when the surface water exchange between the east sea and adjacent marginal seas was active in contrast glacial opal paleoproductivity appears to have been depressed probably because of insufficient nutrient availability resulting from limited vertical ventilation overall toc contents follow the orbital variations high during the interglacial and relatively low during the glacial time however high resolution toc fluctuations are independent of opal concentration which may be attributed more to the preservation of organic matter rather than to the surface water production the high toc contents in the thin dark mud i e tl layers may be due to the enhanced surface water production as well as the intensified bottom water anoxia on the other hand high caco3 contents associated with the tl layers during the glacial and stadial period may be attributed to the reduced dissolution the temporal variations of these geochemical properties are likely to follow the global orbital cycles indicating the significant changes of surface and bottom water properties due to the eustatic sea level fluctuations between the interglacial and glacial period the comparable values of these geochemical properties among the sediment cores suggest that the spatial paleoceanographic conditions in the south korea plateau were consistent and uniform during the late quaternary in spite of a little local discrepancy in amounts of properties and timing of events

orbital and millennial scale paleoceanographic changes in the north eastern japan basin east sea japan sea during the late quaternary two gravity sediment cores gh99 1239 and gh99 1246 obtained from the north eastern japan basin in the east sea japan sea were analyzed for the orbital and millennial scale paleoceanographic changes chronostrati graphically core gh99 1239 represents a continuous sedimentary record since 32 ka based on correlation of distinct lithological markers i e dark layer or tl layer with those in core gh98 1232 collected nearby for core gh99 1246 the age model is constructed through correlation of lightness l values and tephra aso 4 and toya layers with those in the well dated oki ridge core md01 2407 indicating about 134 ka of sedimentation since the latest marine isotope stage mis 6 new geochemical data from both cores corroborate orbital scale paleoceanographic variation such that surface water productivity represented by biogenic opal and total organic carbon toc contents increased during mis 1 and mis 5 caco3 contents do not show such distinct glacial interglacial cycles but were influenced by dissolution and preservation rather than foraminiferal production during the glacial periods when sea ice was prevalent surface water productivity was low and bottom water conditions became anoxic as indicated by high total sulfur ts contents and high mo concentrations the geochemical data further document millennial scale paleoceanographic variability corresponding to a series of thin tl layers in response to dansgaard oeschger cycles but irrespective of the glacial or interglacial periods in particular thin tl layers formed during mis 3 are characterized by less toc about 1 and ts about 0 4 contents and lower mo about 5 p p m concentration whereas those during mis 4 and mis 5 exhibit more toc up to 4 and ts up to 5 contents and higher mo up to 120 p p m concentration such a discrepancy is attributed to different degree of surface water productivity and of bottom water oxygenation which is closely related to the sea level position and extent of ventilation flux of the east china sea coastal water controlled by millennial scale paleoclimatic events is the most critical factor in deciding the properties of tl layers in the north eastern japan basin our results strongly confirm that tl layers in the japan basin also validate the unique feature of basin wide paleoceano graphic signals in the east sea japan sea copyright 2011 john wiley sons ltd

origins and paleoceanographic significance of laminated muds from the ulleung basin east sea sea of japan abstract a detailed facies analysis of long piston core sediments from the ulleung basin reveals four mud facies laminated mud crudely laminated mud bioturbated mud and homogenous mud the laminated and homogeneous muds were most likely deposited from turbidity currents whereas the bioturbated and crudely laminated muds were formed by hemipelagic pelagic sedimentation under well oxygenated and poorly oxygenated bottom water conditions respectively a detailed analysis of vertical distribution of the mud facies together with a chronostratigraphic framework derived from correlative tephra layers with known eruption ages reveals paleoenvironmental changes during the late quaternary during the period between 49 and 23 ka eustatic lowering of sea level facilitated frequent slope failure resulting in repeated deposition of fine grained turbidites on the basin floor normal hemipelagic sediments were intensively bioturbated under well oxygenated bottom water conditions during the period between 23 and 13 to 11 ka deposition from turbidity currents continued but hemipelagic sediments were non bioturbated under poorly oxygenated bottom water conditions the bottom water deoxygenation is attributed to further lowering of sea level during the last glacial period and consequent intensified stratification in the water column by freshwater supply to the nearly isolated sea primary laminae preserved in the crudely laminated mud generally exhibit low compositional bimodality in backscattered electron images which suggests low surface primary productivity and presence of superficial micro bioturbation after rapid rise of sea level at 13 to 11 ka the slopes were stabilized and pelagic sedimentation has prevailed under well oxygenated bottom water conditions

relationship between thermal maturation gradients geothermal gradients and estimates of the thickness of the eroded foreland section southern alberta plains canada abstract analysis of post laramide tertiary uplift and erosion in the southern alberta plains indicates that the greatest erosion occurred in regions where the youngest stratigraphic units are preserved this is consistent with geological structure and the few preserved stratigraphic constraints on erosional history throughout this region erosion is pervasive and the uplift history is commonly constrained by coalification data the analysis of coalification erosion and paleogeothermics are interrelated and knowledge of them is important to understand hydrocarbon generation and tectonic history several independent attempts to analyse coalification erosion and paleogeothermics in this area have given different results the most striking differences are those between estimates derived from the analysis of well profile coalification gradient and those determined using a commonly accepted relationship between the amount of eroded section and the equilibrium moisture content of near surface coals the match between present and paleogeothermal gradient fields is better when the latter technique is used correlation is expected between the late orogenic and present geothermal gradient fields because the hydrodynamically controlled advective heat flow pattern that now dominates geothermal gradients in the mesozoic and tertiary foreland succession was initiated by the growth of topography in the west throughout cordilleran orogeny well profile coalification gradients have significant though commonly unacknowledged uncertainties these uncertainties are propagated in erosion and paleogeothermal gradient calculations ideally the relationship between erosion estimates using well profile coalification gradients and near surface coal properties can be compared unfortunately the uncertainties in well profile coalification gradients prevent this

paleoceanographic change during the last deglaciation east sea of korea foraminiferal assemblage and stable isotopic data are presented for three quaternary piston cores from ulleung basin east sea of korea esk japan sea near the korean peninsula major changes in both temperature and salinity strongly affected surface and deep waters of the esk during the transition from the last glacial maximum lgm to the middle holocene local environmental effects dominated during the lgm and the bolling allerod b a when the esk became semi isolated from the pacific ocean regional global influences dominated following the b a after sufficient reconnection with the pacific this is reflected in the foraminiferal 18o record which was largely salinity controlled before the younger dryas yd and temperature controlled after the yd paleoceanographic changes in the esk during the last deglaciation reflect sequential reconnection with the pacific ocean through gateways first b a in the north tsugaru strait and later holocene in the south korea strait

molybdenum and uranium geochemistry in continental margin sediments paleoproxy potential abstract we measured solid phase mo and u concentrations in marine sediments from the california mexico peru and chile margins to ascertain the behavior of mo and u during early diagenesis in continental margin settings at sites along the california mexico and peru margins where there are estimates of mass accumulation rates authigenic u accumulation rates range from 0 50 nmol m 2 day 1 at the california and mexico margin sites mo accumulation rates range from 0 to 134 nmol m 2 day 1 whereas at the peru margin site rates may be as high as 550 nmol m 2 day 1 we observe relationships between metal accumulation rates and the delivery and burial rates of organic carbon corg in the case of mo there appears to be at least two relationships between metal accumulation rate and organic carbon burial for most of the data presented in this manuscript continental margin sediments have a mo corg accumulation rate ratio of 20 mol mol 1 this value is significantly lower however than those reported for anoxic basins 100 mol mol 1 but is consistent with reported mo corg rain ratios from mexico margin sediment traps in contrast to mo there appears to be a single u corg burial ratio of 5 mol mol 1 which includes a range of environments from anoxic basins and open ocean sites we interpret the relationships between metal accumulation and organic carbon to indicate that the reactions that govern authigenic metal accumulation are primarily sensitive to the delivery and burial of organic carbon in these particular settings however we note that any relationship between metal accumulation and organic carbon could be indirect in the particular case of mo based on what is known about mo geochemistry from the literature it is possible that mo authigenesis is coupled to sulfur cycling in many of the environments covered by this study and that the observed association between mo and organic carbon burial is a consequence of the coupling between carbon and sulfur burial using the observed relationships between mo and corg burial as well as constraints from the mo isotope budget we estimate that continental margin sediments are an important sink for mo the magnitude of this sink 0 4 108 mol y 1 or larger may be as much as one quarter of the oceanic removal term and is likely to be larger than the modern anoxic basin sink

global warming may have slowed down the deep conveyor belt of a marginal sea of the northwestern pacific japan sea weakening of the abyssal circulation conveyor belt in the japan sea during the 20th century is deduced from the decreasing trend of bottom dissolved oxygen o2 this trend indicates a shortened o2 supply caused by too inactive conveyor belt to compensate for biological o2 consumption at the bottom of the sea recent climatic changes during the winter season in the northern japan sea may play a significant role in prohibiting the formation of surface seawater dense enough to sink to the bottom it is predicted that the japan sea bottom water will become anoxic within a few hundred years as it was in the last glacial maximum

orbital scale stratigraphy and high resolution analysis of biogenic components and deep water oxygenation conditions in the japan sea during the last 640 kyr abstract paleoceanographic conditions in the japan sea changed drastically during the late quaternary in association with orbital and suborbital cycles and glacio eustatic sea level changes however few studies have examined long term sediment records older than 160 ka because of the lack of long and continuous cores and the difficulty in constructing high resolution age models in this study we first constructed an orbital scale stratigraphy of the sediments covering the last 640 kyr by comparing the specmap 18o curve and the 18o curve of planktonic foraminifera 18opf in the japan sea together with the combination zones of dominant planktonic foraminifera species then we reconstructed temporal variations in biogenic silica biosil and biogenic carbonate biocarb contents calculated from high resolution major element analysis data determined by an xrf microscanner in order to evaluate the deep water oxygenation conditions we also defined excess s as the difference between the content of s in the sediments and that for normal marine sediments calculated from the organic carbon content corg estimated from lightness l by assuming a total sulfur content stotal corg ratio of 0 36 and examined its variability biosil shows orbital scale variation and is generally low except during interglacial maxima when global sea level was high enough to allow a strong influx of the tsushima warm current biocarb shows orbital and suborbital scale variations and tends to be higher in dark layers deposited during glacial stages whereas the relationship is reversed during interglacial stages the low biocarb in dark layers deposited during interglacial stages is probably due to dissolution of biogenic carbonate caused by the increase in surface productivity as a result of the strong influx of nutrient rich east china sea coastal water and consequent increase in surface productivity and decomposition rate of organic matter in the intermediate water excess s tends to be higher in thicker dark layers deposited during glacial maxima when the sea level dropped below 90 m compared to adjacent light layers suggesting development of euxinic deep water conditions during these periods the results demonstrated the presence of orbital and suborbital scale variations in biosil and biocarb and their association with dark and light layers in the japan sea that reflect variations in the nature and strength of inflow through the tsushima strait controlled by both climatic and sea level changes whereas higher excess s reflects the development of euxinic deep water condition during glacial maxima in association with glacio eustatic sea level drops below 90 m during the last 640 kyr

late pleistocene dark laminated mud layers from the korea plateau western east sea japan sea and their paleoceanographic implications abstract a variety of approaches were applied to a 11 1 m long sediment core ebp 4 from the korea plateau one of the bathymetric highs in the western part of the east sea japan sea to understand late pleistocene paleoenvironmental change the chronostratigraphy of the core was established using a radiocarbon age dark laminated mud dlm layers with known ages the oxygen isotope 18 o curve of planktonic foraminifera biogenic opal and total organic carbon toc contents downcore changes in the carbon nitrogen c n ratio as well as their isotopic ratio 13 c and 15 n in organic matter although interrupted by several pumice lapilli layers the core bottom represents marine isotope stage mis 8 and spans more than 250 kyr of paleoceanographic history of the western east sea japan sea paleoenvironmental conditions during mis 2 and mis 6 are clearly distinguishable represented by the negative shift of 18 o values of planktonic foraminifera resulting from surface water freshening due to basin isolation caused by eustatic sea level lowering the corresponding dark laminated mud dlm i ii a ii b and iii layers formed during glacial maxima are characterized by strong mo and total sulfur ts enrichment in anoxic conditions which indicates a stagnant and strongly stratified water column structure biogenic opal contents can be a useful indicator to confirm the chronostratigraphic assessment and can also identify periods of high surface water productivity in the east sea japan sea particularly during interglacial times in contrast glacial paleoproductivity might be low compared to the interglacial because of insufficient nutrient availability resulting from limited vertical ventilation the 13 c and 15 n values of sedimentary organic matter also emphasize increased terrestrial input during the glacial maxima exhibiting highly depleted 13 c and 15 n values in all dlm layers sea level induced paleoenvironmental changes associated with glacial interglacial variations are identified from the korea plateau confirming these events occurred throughout the whole east sea japan sea

paleoenvironmental changes in the japan sea during the last 85 000 years five distinct changes in the paleoenvironment of the japan sea within the last 85 000 years are revealed from the sedimentary record of a piston core recovered from the oki ridge changes in both surface and deepwater conditions are registered by changes in lithology calcium carbonate content organic carbon content oxygen and carbon isotope ratios and microfossil assemblages including calcareous nannoplankton diatoms radiolaria and foraminifera between 85 and 27 ka the warm tsushima current did not flow into the japan sea and cold surface water conditions prevailed environments at the seafloor fluctuated between dysaerobic to weakly oxic conditions between 27 and 20 ka freshwater input to the japan sea probably from the huang ho river in china stratified the water column and the severe anoxic conditions eliminated most benthic fauna between 20 and 10 ka the cold oyashio current flowed into the japan sea through the tsugaru strait reestablishing deepwater ventilation shallow water benthic assemblages of the north pacific ocean subsequently colonized the japan sea and occupied the vacant niches of the deep basins between 10 and 8 ka the foraminifer compensation level fcl gradually rose to a depth shallower than 1000 m and bottom conditions changed from dysaerobic to oxic at 10 ka the warm tsushima current started to flow into the japan sea through the tsushima strait to establish the modern oceanographic regime which has existed since 8 ka the eustatic sea level during the last glacial maximum was above the sill depths 130 m of the tsushima and tsugaru straits assuming that tectonic movements at these straits were negligible for the last 20 ka

crustal deformation at the sumatran subduction zone revealed by coral rings analyses of coral rings grown in the interval 1970 1997 reveal a geographically distinct pattern of interseismic uplift off sumatra s western coast at distances less than 110 km from the sumatran trench coral reefs are submerging as fast as 5 mm y at 130 and 180 km distance from the trench they are emerging at similar rates we suggest that a locked or partially locked patch located above 30 km depth on the upper surface of the subducting oceanic plate generates this pattern

remigration and leakage from continuous shale reservoirs insights from the sichuan basin and its periphery china shale gas in the sichuan basin and its periphery potentially plays an important role in the world shale gas industry an understanding of remigration and leakage from continuous shale reservoirs is very important for shale gas exploration especially in the sichuan basin and its periphery the shale gas accumulation models that relate to remigration and leakage were developed within the wufeng and longmaxi black shales in the jiaoshiba and the youyang blocks first a tectono sedimentary history of the wufeng and longmaxi black shales in the sichuan basin and its periphery was developed based on the published literature the history exhibits a continuous distribution of high quality wufeng and longmaxi black shale which is the foundation of the shale gas formation second the shale gas remigration accumulation model in the anticlines was clarified by using data collected from the shale gas fields in jiaoshiba block the shale gas model for the jiaoshiba block was developed on the basis of a continuous shale reservoir distribution differentiated structural deformation and a gas self sealed system third the shale gas fault failure leakage model in the fault blocks and the erosion model in the residual areas were revealed based on the shale reservoir and shale gas content heterogeneity in the youyang block these two models were validated by available data including 13 two dimensional seismic lines and 2 shale gas exploration vertical wells in the youyang block shale gas areas with high gas resource and gas production rates in the anticlines were defined by the remigration accumulation model the fault failure leakage model was used to find shale gas with limited commercial potential whereas commercial shale gas was largely lacking according to the erosion residual model the study on remigration and leakage from continuous shale reservoirs in the sichuan basin and its periphery can be used to better understand and improve the exploration efforts based on resource preservation

the supply and accumulation of silica in the marine environment rivers and submarine hydrothermal emanations supply 6 1 1014g sio2 yr to the marine environment approximately two thirds of the silica supplied to the marine environment can be accounted for in continental margin and deep sea deposits siliceous deep sea sediments located beneath the antarctic polar front convergence account for over a fourth 1 6 1014g sio2 yr of the silica supplied to the oceans deep sea sediment accumulation rates beneath the polar front are highest in the south atlantic with values as large as 53cm kyr during the last 18 000 yr siliceous sediments in the bering sea sea of okhotsk and subarctic north pacific accumulate 0 6 1014g sio2 yr or 10 of the dissolved silica input to the oceans the accumulation of biogenic silica in estuarine deposits removes a maximum of 0 8 1014g sio2 yr although estuarine silica versus salinity plots indicate extensive removal of riverine silica from surface waters the removal rates must be considered as maximum values because of dissolution of siliceous material in estuarine sediments and bottom waters siliceous sediments from continental margin upwelling areas e g gulf of california walvis bay or peru chile coast have the highest biogenic silica accumulation rates in the marine environment 69 g sio2 cm2 kyr despite the rapid accumulation of biogenic silica upwelling areas account for less than 5 of the silica supplied to the marine environment because they are confined laterally to such small areas

millennial scale fluctuations in seasonal sea ice and deep water formation in the japan sea during the late quaternary abstract the east asian winter monsoon is characterized by cold dry air blowing from the siberian high to the surrounding lows this cold wind cools the surface water along the russian coast of the japan sea modern oceanographic observations indicate that sea ice formation along this coast during an extremely cold winter is an important process for deep water formation thus formation of both seasonal sea ice and deep water masses in the japan sea are closely related to the east asian winter monsoon two sediment cores were analyzed to reconstruct the history of sea ice expansion and deep water formation seasonal sea ice history was reconstructed from the occurrence of ice rafted debris ird in a core from the northeastern japan sea whereas the deep water ventilation history was estimated on the basis of records of a deep dwelling radiolarian species cycladophora davisiana in a core from the southwestern japan sea in the records of sea ice expansion and deep water ventilation for the last 160 ky clear fluctuations on a millennial timescale were observed during marine oxygen isotope stages 3 5 some of the peaks in sea ice formation and c davisiana abundance occurred contemporaneously indicating strong surface cooling along the russian coast by a strong winter monsoon decoupling of the two records might have occurred because of surface water stratification caused by the freshening of surface water in relation to high precipitation in summer synchronicity of high ird peaks with north atlantic heinrich events suggests that high latitude climate changes related to the bond cycle also occurred in the asian monsoon region on shorter timescales ird occurrence was not clearly related to dansgaard oeschger cycles which are revealed in the alternating dark and light layers in the late quaternary japan sea sediments therefore during the studied period strong east asian winter monsoons did not have a simple see saw like relationship with strong summer monsoons

time and temperature in petroleum formation application of lopatin s method to petroleum exploration n v lopatin in the soviet union has developed a method for taking both time and temperature into account as factors in thermal maturation of kerogen lopatin s time temperature index of maturity tti values correlate with the thermal regimes corresponding to generation and preservation of hydrocarbons because such information is potentially of great interest for oil exploration a calibration and evaluation have been made of lopatin s method within the limitations of the data presently available the following statements can be made 1 the rate of the chemical reactions involved in thermal maturation of organic material appears to double with every 10 c 18 f rise in temperature 2 threshold values of lopatin s time temperature index of maturity tti are 15 onset of oil generation 75 peak oil generation 160 end oil generation 500 40 oil preservation deadline 1 000 50 oil preservation deadline 1 500 wet gas preservation deadline 65 000 dry gas preservation deadline 3 tti values calculated from lopatin reconstructions consistently agree with other maturation parameters commonly used by petroleum geochemists potential applications of lopatin s method for oil exploration include timing of oil generation calculation of volume of hydrocarbons generated within a basin and determination of economic deadlines

increased negative anomalies of sedimentary organic matter δ13c and δ15n values in the east sea sea of japan during the full glaciation of the late quaternary abstract glacio eustatic sea level fluctuations and subsequent paleoceanographic changes in the east sea sea of japan have been identified by unique sedimentary features and their geochemical properties throughout the late quaternary sediments these events were synchronous basin wide the effect of sea level change in the east sea is fundamental to the anoxia of bottom water resulting from the stagnant strongly stratified water column with limited ventilation during the glacial periods the four sediment cores collected from the japan basin yamato basin and korea plateau in the east sea showed extraordinarily co varied 1 3 c and 15 n values of sedimentary organic matter representing distinct negative anomalies of both isotopes for the thick dark laminated mud layers formed during full glaciations mis 2 and mis 6 of the late quaternary the most plausible cause to induce such peculiar isotope variations is the enhanced contribution of terrestrial organic detritus in addition to the anoxic diagenetic condition in the bottom water during the glacial times both of which are characterized by relatively low 13 c and 15 n values the aeolian contribution of terrigenous particles in the form of kosa supplied from inland china was intensified in the east sea during the last glacial maximum during the glacial periods the anoxic decay of sedimentary organic matter may lead not only to the reduction of 13 c values attributed to the selective preservation of 13 c depleted organic compounds but also to the decrease of 15 n values due to the addition of 15 n depleted organic matter by using soluble nitrogenous compounds and the bacterial growth adding 15 n depleted biomass to the residual materials thus the results argue against the utility of 1 3 c and 15 n values of sedimentary organic matter as a proxy of paleoproductivity and atmospheric p co 2 levels in a marginal sea environment such as the east sea

palaeoenvironmental implications of coal formation in dobrudzha basin bulgaria insights from organic petrological and geochemical properties abstract the dobrudzha basin in northeast bulgaria contains 86 coal seams distributed within three coal bearing formations of late carboniferous age this study presents the organic petrological and geochemical characteristics of coals from the makedonka and krupen formations containing some of the most prominent coal seams these were characterized by means of proximate and rock eval analyses vitrinite reflectance measurements organic petrography and gcms analysis in order to establish variations in vegetation and depositional settings based on random vitrinite reflectance avg 0 7 r r and toc contents avg 80 daf the coals can be classified as low rank bituminous high volatile b c low tmax values avg 430 c further indicate a low degree of organic matter maturity the low to moderately high ash yields together with the presence of shaly partings and generally low sulfur contents are consistent with peat formation in a fluviatile sedimentary environment petrographic analysis reveals complex maceral composition with abundant liptinite and inertinite the predominance of detrovitrinite and the almost complete lack of strongly gelified macerals argue for enhanced humification of the plant tissues and peat formation in relatively dry environments above water table the distributions of n alkanes diterpenoids and steranes indicate that the organic matter originated from terrestrial vascular plants the high pristane phytane ratios point to peat deposition under oxic conditions low concentrations of hopanes argue for limited bacterial degradation of the organic matter possibly due to low ph conditions during peatification the presence of tetracyclic diterpanes and their aromatic counterparts is attributed to pre gymnosperm cordaitean input the existence of cordaiteans although as minor component of the palaeovegetational communities is further evidenced by the presence of trace amounts of aromatic arborane fernane derivatives in almost all studied samples the occurrence of combustion derived pahs in all studied samples is consistent with the abundant inertinite and indicates frequent forest fires during peat formation

paleoclimatic significance of eolian carbonates supplied to the japan sea during the last glacial maximum laminated sediments deposited under anoxic bottom waters in the japan sea during the last glacial maximum lgm contain extremely well preserved calcareous microfossils and eolian carbonates the radiocarbon age difference between bulk sediment and monospecific planktonic foraminifera in discrete laminae from a core in the southern japan sea implies that 40 of the total carbonates in the sediments at the lgm are of eolian origin extrapolation of this result yields a rate of supply of eolian carbonates of 2800 tons d 1 to the entire japan sea during the lgm the climatic significance of this flux potentially lies in its broader geographic extension particularly in the interaction of the carbonate bearing dust with shallow corrosive north pacific waters and with rain in the atmosphere by increasing the alkalinity of such waters and by enhancing the biological pump the dust flux could have increased co2 absorption by both the ocean and rain during the lgm

abrupt ventilation changes in the japan sea over the last 30 ky evidence from deep dwelling radiolarians abstract the japan sea has its own deep circulation system with its deeper parts occupied by cold and highly oxygenated water formed by winter convection in its northwestern reaches we elucidate the modern depth distribution of radiolarian species and their relation to water masses from the study of plankton tows and surface sediments cycladophora davisiana occurs in a depth interval between 1000 m and 2000 m deep layer of jspw japan sea proper water and actinomma boreale leptoderma group in depths below 2000 m bottom layer of jspw the study of seven sediment cores located in water depths ranging from 807 to 3613 m show that the radiolarian assemblages have varied since 30 cal ka bp indicating changes in water ventilation strength in this marginal sea during the interval from 30 to 17 cal ka bp ventilation was restricted to an intermediate layer beneath the low salinity surface water while the deeper zone was filled with static anoxic water deep ventilation began abruptly at 14 cal ka bp cold and oxygen rich water began to sink into the bottom layer as a result of cold oceanic inflow from the northwestern pacific through the tsugaru strait in the north deep convection activity increased from 13 to 12 cal ka bp which coincides with the younger dryas like cooling event and then stopped at 12 11 5 cal ka bp bottom water ventilation during the holocene has been dependent on high salinity inflow through the tsushima strait in the south and winter cooling in the northwestern part of the japan sea deep water was being actively formed in the early holocene in contrast to the static bottom water this bottom water formation has resulted in relatively constant water composition since 9 cal ka bp with the overall increase in high salinity oceanic water inflow although the latter decreased transiently from 7 to 5 cal ka bp in concert with climatic warming

mo total organic carbon covariation in modern anoxic marine environments implications for analysis of paleoredox and paleohydrographic conditions 1 sedimentary molybdenum mo s has been widely used as a proxy for benthic redox potential owing to its generally strong enrichment in organic rich marine facies deposited under oxygen depleted conditions a detailed analysis of mo s total organic carbon toc covariation in modern anoxic marine environments and its relationship to ambient water chemistry suggests that 1 mo s while useful in distinguishing oxic from anoxic facies is not related in a simple manner to dissolved sulfide concentrations within euxinic environments and 2 patterns of mo s toc covariation can provide information about paleohydrographic conditions especially the degree of restriction of the subchemoclinal water mass and temporal changes thereof related to deepwater renewal these inferences are based on data from four anoxic silled basins the black sea framvaren fjord cariaco basin and saanich inlet and one upwelling zone the namibian shelf representing a spectrum of aqueous chemical conditions related to water mass restriction in the silled basin environments increasing restriction is correlated with a systematic decrease in mo s toc ratios from 45 5 for saanich inlet to 4 5 1 for the black sea this variation reflects control of mo s by mo aq which becomes depleted in stagnant basins through removal to the sediment without adequate resupply by deepwater renewal the basin reservoir effect the temporal dynamics of this process are revealed by high resolution chemostratigraphic data from framvaren fjord and cariaco basin sediment cores which exhibit long term trends toward lower mo s toc ratios following development of water column stratification and deepwater anoxia mo burial fluxes peak in weakly sulfidic environments such as saanich inlet owing to a combination of greater mo aq availability and enhanced mo transport to the sediment water interface via fe mn redox cycling and are lower in strongly sulfidic environments such as the black sea and framvaren fjord these observations demonstrate that at timescales associated with deepwater renewal in anoxic silled basins decreased sedimentary mo concentrations and burial fluxes are associated with lower benthic redox potentials i e more sulfidic conditions these conclusions apply only to anoxic marine environments exhibiting some degree of water mass restriction e g silled basins and are not valid for low oxygen facies in open marine settings such as continent margin upwelling systems

preservation of elemental and isotopic source identification of sedimentary organic matter the amount and type of organic matter in the sediments of lakes and oceans contribute to their paleoenvironmental and paleoclimatological records only a small fraction of the initial aquatic organic matter survives destruction and alteration during sinking and sedimentation selective degradation modifies the character of the surviving small fraction of organic matter which becomes incorporated in bottom sediments organic matter alterations can continue to sub bottom depths of hundreds of meters corresponding to millions of years source and paleoenvironmental information nonetheless remains preserved in the molecular elemental and isotopic compositions of organic matter c n and 13c values of total organic matter in particular appear to retain paleoenvironmental information for multi myr time periods

instability of bottom water redox conditions during accumulation of quaternary sediment in the japan sea the concentrations of cd cr cu mo ni sb u v and zn were measured in early quaternary sediment 1 32 to 1 08 ma from the oki ridge in the japan sea the elements were partitioned between a detrital fraction composed of terrigenous and volcaniclastic aluminosilicate debris and a marine fraction composed of biogenic and hydrogenous debris derived from seawater the most important factors controlling minor element accumulation rates in the marine fraction were 1 primary productivity in the photic zone which largely controlled the flux of particulate organic matter bound minor elements settling through the water column and onto the seafloor and 2 bottom water redox which determined the suite of elements that accumulated directly from seawater this marine fraction of minor elements on oki ridge recorded six periods of high minor element abundance assuming a constant bulk sediment accumulation rate each period lasted roughly 5 000 to 10 000 years with a 41 000 year cycle accumulation rates of individual elements such as cd mo and u suggest sulfate reducing conditions were established in the bottom water during the 10 000 year periods accumulation rates of cr and v during the intervening periods are indicative of less reducing denitrifying conditions interelement ratios for example cu mo v cr and sb mo further reflect bottom water instability such that bottom water redox actually varied from sulfate reducing to denitrifying during the periods of highest minor element accumulation rates it varied from denitrifying to oxidizing during the intervening periods sediment lithology supports these interpretations of the minor element distributions the sediment is finely laminated for several of the periods represented by cd mo and u maxima and weakly laminated to bioturbated for the intervening periods the geochemistry of this sediment demonstrates the unambiguous signal of mo principally but of several other minor elements as well in recording sulfate reducing conditions in bottom water the forcing function that altered their accumulation that is that altered primary productivity and bottom water redox conditions is problematic currently held opinion suggests that o2 depletion was most strongly developed during glacial advances low sea level during such times is interpreted to have enhanced primary productivity and restricted bottom water advection

burial history and thermal maturity rocky mountain front ranges foothills and foreland east central british columbia and adjacent alberta canada the regional pattern of maturation of cretaceous strata in the study area was determined from vitrinite reflectance measurements maturation increases from west to east across the foothills to a maximum near the eastern limit of foothills deformation and decreases farther east maturation along the eastern limit of deformation also decreases northward significantly reflectance measurements from carboniferous strata exposed in the front ranges are much lower than values from the lower cretaceous near the eastern limit of deformation modeling using burial history curves indicates the regional maturation pattern largely reflects variations in the depth and or duration of burial beneath maastrichtian eocene foredeep deposits however differential vertical movements associa ed with the peace river arch embayment in the carboniferous triassic early cretaceous and maastrichtian eocene had an important effect on the maturation pattern determined and estimated maturation levels for reservoir strata are consistent with the known occurrences of gas fields and oil pools except along the relatively unexplored western margin of the study area there moderate maturation levels indicate a potential for wet gas or oil preservation in shallow structures containing triassic and lower carboniferous carbonates in the south in the north structures in the western foothills deforming triassic strata with lower levels of maturation are breached

maturity studies in the carboniferous dobroudja coal basin northeastern bulgaria coalification clay diagenesis and thermal modelling abstract in northeastern bulgaria upper paleozoic coals are only found in the dobroudja basin this coal basin belongs to a variscan foredeep which is at present covered by a thick 1300 1500 m mesozoic cenozoic complex moesian platform the coal seams are associated with alternating sandstones siltstones and shales deposited under fluvio deltaic environmental conditions previous coalification studies on the basin have recorded high volatile to low volatile bituminous ranks the construction of coalification profiles increase of vitrinite reflectance with depth in ten wells from the dobroudja coal basin has enabled us to interpret the paleotemperature regime the simulation of the burial and thermal history of the upper carboniferous formations in the dobroudja coal basin yielded paleogeothermal gradients between 45 and 71 c km the results show an increase of the paleogeothermal regime from the northwest towards the southeast the existence of a high paleoheatflow is in accordance with data from other carboniferous basins in europe due to high vertical paleogeothermal gradients and deep burial the maturation of the formations was completed during the late carboniferous the relatively large maturation range of the upper carboniferous sediments enables comparison among different thermal indicators vitrinite reflectance spectral fluorescence maximum pyrolysis indices illite crystallinity and bulk clay mineralogy and their behavior in the course of diagenesis

surface water changes recorded in late quaternary marine sediments of the ulleung basin east sea japan sea abstract in order to reconstruct past sea surface temperature sst and salinity sss in the east sea japan sea this study investigated the oxygen isotopic composition of the planktonic foraminifer globigerina bulloides and the degree of unsaturation of alkenones in bulk sediments of core ty99pc18 recovered from the southeastern part of the ulleung basin east sea between 11 and 15 cal kyr bp the surface waters were 2 4 c cooler than today the surface salinity was 12 lower during 14 15 cal kyr bp than today then increased after 14 cal kyr bp but remained lower during 11 14 cal kyr bp than present values between 14 and 15 cal kyr bp the northern east china sea surface waters were likely to be greatly diluted by fresh water discharge from land and coastal waters would have flowed into the east sea through the korea strait during 11 14 cal kyr bp the southern input waters most likely changed from fresh water influenced coastal water to open ocean water the increased salinity probably enhanced active deep water convection at that time during 7 11 cal kyr bp the surface waters were warmer 1 c and more saline 1 3 than today indicating that the warm and saline kuroshio current became stronger and that one of its branches flowed into the east sea during this time interval the cold 2 c and less saline waters 1 at 3 6 cal kyr bp may indicate a suppression of the kuroshio current the sst and sss values are close to the present values at about 3 cal kyr bp suggesting that the physiological conditions of the east sea approached that of the present at this time

sediment fabrics oxygenation history and circulation modes of japan sea during the late quaternary abstract the quaternary hemipelagic sediments of the japan sea are characterized by centimeter to decimeter scale alternations of heavily bioturbated organic poor light layers and finely laminated organic rich dark layers these dark and light layers which can be correlated throughout the deeper part of the basin are considered to reflect changes in bottom water oxygenation however depositional mechanisms responsible for individual dark layers and causes of oxygen depletion are not fully understood two possible settings for deposition of organic rich dark layers are recognized one is a stratified ocean like the black sea where limited vertical advection results in euxinic conditions in the deeper parts of the basin the other is an upwelling region like the arabian sea where the oxygen minimum zone is intensified by enhanced nutrient upwelling and surface productivity in this study fabrics of hemipelagic sediments deposited in the japan sea during the last 160 ka were studied in three cores collected from different latitudes and water depths fabrics were classified into 4 classes based on corresponding bottom water oxygenation level five dark layer types were defined based on the distribution patterns of sediment fabric classes within each dark layer comparison of dark layer types at shallower and deeper sites in a chronologic framework provided evidence for five different modes of deep water circulation these circulation modes which reflect relative intensities of upwelling and density stratification appear to be related to global sea level changes as well as climate impact on the nature of water influx through the tsushima strait

detailed japan sea paleoceanography during the last 25 kyr constraints from ams dating and δ18o of planktonic foraminifera abstract we have reconstructed paleoceanographic changes in the japan sea for the period from the last glacial maximum lgm to the present using expanded paleoclimate proxy records from two cores together with previously published results from three others a suite of new accelerated mass spectrometer ams 14 c dates provides chronologies that differ from earlier age models and suggest correlation between conditions in the japan sea changes in the north pacific and global sea level and climate changes we present evidence that reduced salinity of the japan sea surface water during the late pleistocene was due primarily to the increased importance of the precipitation evaporation balance at a time when lowered sea level had reduced water exchange with the pacific to a few percent of the present value

anoxia vs productivity what controls the formation of organic carbon rich sediments and sedimentary rocks discussion the prevailing explanation for the origin of organic rich sediments and rocks invokes deposition under conditions of anoxia however recent research suggests that high primary production and not water column anoxia provides the first order control on the accumulation of organic rich facies in the modern oceans oxygen minima do not appear to have any direct effect on carbon accumulation in continental margin or marginal sea environments sediments accumulating in the modern black sea the type euxinic basin are not particularly enriched in organic matter despite the presence of an anoxic water column although a sapropel containing extremely high carbon concentrations was deposited during the holocene at a time when the basin was oxic results of a recently published co pled ocean atmosphere model indicate that during the cretaceous thermohaline and surface circulation in the oceans was similar to or more intense than modern conditions despite the overall equable climate such conditions confound the idea that circulation in the cretaceous atlantic for example was punctuated by oceanic anoxic events brought about by more sluggish circulation sporadic temporal and spatial increases in primary production reflecting changes in the behavior and or state of the ocean atmosphere system constitute a more tenable explanation for the occurrence of modern and quaternary carbon rich sediments and cretaceous black shales consequently the fundamental control on the accumulation of carbon rich facies in the oceans and marginal seas is not the presence or absence of anoxia

late pliocene to early pleistocene 2 4 1 25 ma paleoproductivity changes in the bering sea iodp expedition 323 hole u1343e abstract late pliocene to early pleistocene paleoproductivity changes in the bering sea were reconstructed using geochemical concentrations and mass accumulation rates mars of caco 3 biogenic opal and total organic carbon toc and sedimentary nitrogen isotope ratios 15 n at iodp expedition 323 hole u1343e drilled in the northern slope area 1956 m deep of the bering sea caco 3 concentration is generally low but prominent caco 3 peaks occur intermittently due to subseafloor authigenic carbonate formation rather than biogenic accumulation regardless of glacial interglacial variations biogenic opal concentrations reflect orbital scale glacial interglacial variations however toc concentration did not show clear glacial interglacial variation probably due to poor preservation the sedimentary 15 n values vary synchronously with biogenic opal concentration on orbital timescales the co varying pattern of opal productivity and 15 n values at hole u1343e is a result of nutrient utilization controlled by diatom productivity in the bering slope area where fe is not a limiting factor biogenic opal and toc mars showed a temporal shift at around 1 9 ma from a high productivity period under nutrient enriched conditions to a low productivity period under relatively nutrient depleted conditions high diatom productivity with low 15 n values before 1 9 ma is associated with abundant nutrient supply by upwelling in relation to strong surface current system this productivity decrease at about 1 9 ma was also found in the southern bering sea site u1341 and may be related to global opal reorganization

fine structure of dark layers in the central japan sea and their relationship with the abrupt climate and sea level changes over the last 75 ka inferred from lithophysical geochemical and pollen results abstract high resolution of the color lightness productivity proxies toc chlorin caco 3 ba bio mo and u and lithological description defined alternation of dark layers dls and light layers in sediment core lv53 23 recovered from the central japan sea west yamato rise over the last 75 ka age model was constructed by ams 14c data tephrochronology 18 o of planktonic foraminifera record and the correlation of dls with lightness of japan sea core md01 2407 and with millennial interstadials recorded in the greenland ice cores and east asia stalagmites regional interstadials were also independently established and dated by vegetation amelioration of the surrounded land inferred from the pollen results correlation of the dls with millennial scale climate and sea level changes indicate that both interstadial warming and sea level fluctuations influence on its formation providing their individual features during mis 3 with sea level above 90 m dl was formed mostly consistent with the tada et al 1999 s hypotheses during mis 2 and 4 when sea level was nearly and below 90 m sea level descending led to water column stratification oxygen depletion in bottom water and facilitates the dls formation high resolution lightness and productivity proxies defined the subtle structure of pronounced interstadials 14 and 12

orbital and millennial scale changes of radiolarian assemblages during the last 220 kyrs in the japan sea abstract significant abundance changes of seven radiolarian species during the last 220 kyrs in the japan sea are reported herein based on three sediment cores during the interglacial periods warm water species the tetrapyle octacantha group and warmer high nutrient water species lithomelissa setosa occurred commonly which may indicate inflows of the tsushima warm current on the other hand cold water species such as ceratospyris borealis and stylochlamydium venustum dominated the assemblage during the glacial periods when the japan sea was mostly isolated from the adjacent seas due to lower eustatic sea level however at glacial maxima the habitat of s venustum was strongly limited due to low salinity surface waters the abundance of the deep water species cycladophora davisiana seems to have changed significantly possibly related to the intrusion of oxygen and organic materials into deeper waters higher abundances of this species in mis marine isotope stage 1 mis 3 and mis 5c resulted from well ventilated deep water and high organic flux while its low abundance during the glacial maxima and mis 5e was probably caused by oxygen poor deep water millennial scale variations of c davisiana abundance show high abundance at the transition intervals from interstadial to stadial periods of the dansgaard oeschger cycles the disappearance events of lychnocanoma nipponica sakaii and amphimelissa setosa were recognized at 54 ka and 85 ka respectively both of these events in the japan sea can be correlated with those in the north pacific bering sea and sea of okhotsk

geochemical and mineralogical changes in a coal seam due to contact metamorphism sydney basin new south wales australia abstract the mineralogical changes in a bituminous coal seam thermally altered by a small basaltic intrusion have been investigated using electronic low temperature oxygen plasma ashing x ray diffraction and other laboratory techniques an assemblage dominated by montmorillonite and well crystallized kaolinite in the area away from the intrusion passes laterally to one dominated by illite and poorly crystallized kaolinite along with abundant dolomite and calcite at the actual contact point geochemical considerations of both the mineral matter and the igneous rock suggest that the changes in the clay fraction were produced by heating to temperatures of between 400 and 650 c for a relatively short period coupled with migration of potassium from the intrusive body into the coal seam heating at lower temperatures although causing an increase in vitrinite reflectance does not appear to have had a particularly significant effect at all on the clay minerals in the coal seam

evidence for general instability of past climate from a 250 kyr ice core record recent results1 2 from two ice cores drilled in central greenland have revealed large abrupt climate changes of at least regional extent during the late stages of the last glaciation suggesting that climate in the north atlantic region is able to reorganize itself rapidly perhaps even within a few decades here we present a detailed stable isotope record for the full length of the greenland ice core project summit ice core extending over the past 250 kyr according to a calculated timescale we find that climate instability was not confined to the last glaciation but appears also to have been marked during the last interglacial as explored more fully in a companion paper3 and during the previous saale holstein glacial cycle this is in contrast with the extreme stability of the holocene suggesting that recent climate stability may be the exception rather than the rule the last interglacial seems to have lasted longer than is implied by the deep sea specmap record4 in agreement with other land based observations5 6 we suggest that climate instability in the early part of the last interglacial may have delayed the melting of the saalean ice sheets in america and eurasia perhaps accounting for this discrepancy

a 36 kyr geochemical record from the sea of japan of organic matter flux variations and changes in intermediate water oxygen concentrations intervals of organic c and carbonate rich laminated sediments occur in the sea of japan with roughly the same frequency as temperature changes observed in greenland ice cores providing clear evidence of rapid oceanographic change during the past 36 kyr planktonic foraminiferal 18o data suggest that only the laminated sediments deposited during the last glacial maximum lgm and perhaps one other interval formed during a period of increased water column stratification sedimentary re and mo data are consistent with bottom waters that were sulfidic during the lgm and suboxic during other laminated intervals results of a numerical model of corg and re burial are consistent with a mechanism whereby an increased corg flux to the seafloor drove oxygen concentrations toward depletion during times of deposition of the suboxic laminated intervals such a process could have resulted from increased upwelling driven either by increased deep water formation due to colder and or more saline surface waters or by stronger northeasterly monsoonal winds

land ocean linkages over orbital and millennial timescales recorded in late quaternary sediments of the japan sea late quaternary sediments of the japan sea are characterized by centimeter to meter scale alternations of dark and light layers which are synchronous basinwide high resolution analyses of the sediments from ocean drilling program site 797 reveal that deposition of the meter scale alternations reflect variations in paleoceanographic conditions which were closely associated with glacio eustatic sea level changes through the modulation of the volume and character of the influx to the sea through the tsushima strait the centimeter to decimeter scale alternations reflect millennial scale variations which are possibly associated with dansgaard oeschger d o cycles with each dark layer appearing to correspond to an interstadial this variability is attributed to the development of a humid climate in central to eastern asia and the consequent increase in discharge from the huanghe and changjiang rivers during interstadials this caused expansion of the east china sea coastal water ecscw which penetrated more strongly into the japan sea the increased influence of the lower salinity nutrient enriched ecscw reduced deep water ventilation and enhanced the surface productivity leading to the development of anoxic bottom waters and deposition of the dark layers thus the centimeter to decimeter scale alternations of the dark and light layers record wet and dry cycles in central to eastern asia possibly associated with d o cycles

sea level surface salinity of the japan sea and the younger dryas event in the northwestern pacific ocean abstract the japan sea was profoundly different during glacial times than today available 18 o evidence indicates that sea surface salinity was lower by several per mil this probably increased the stability of the water column and caused anoxic sedimentary conditions in the deep sea as shown by the absence of benthic microfossils and the presence of laminated sediment these changes are likely related to the effects of late quaternary sea level change on the shallow sills ca 130 m across which the japan sea exchanges with the open ocean the hwang he yellow river has previously been implicated as the source of fresh water to the japan sea during glaciation but the possible roles of the amur river and excess precipitation over evaporation must also be considered ambiguous radiocarbon chronologies for the latest quaternary of japan sea cores do not adequately constrain the timing of salinity lowering previous studies have suggested that lowest sea surface salinity was achieved 27 000 to 20 000 14 c yr b p however if global sea level fall restricted exchange with the open ocean circulation then lowest salinity in the japan sea may have occurred as recently as 15 000 to 20 000 yr ago when sea level was lowest if this alternative is correct then as sea level abruptly rose about 12 000 yr ago relatively fresh water must have been discharged to the open pacific this might have affected the dynamics of outflow local faunal and floral expression of the polar front and stable isotope ratios in foraminifera these environmental changes could be misinterpreted as evidence for the cooling of younger dryas age which has not been identified in nearby terrestrial records

age dating and the orbital theory of the ice ages development of a high resolution 0 to 300 000 year chronostratigraphy using the concept of orbital tuning a continuous high resolution deep sea chronostratigraphy has been developed spanning the last 300 000 yr the chronology is developed using a stacked oxygen isotope stratigraphy and four different orbital tuning approaches each of which is based upon a different assumption concerning the response of the orbital signal recorded in the data each approach yields a separate chronology the error measured by the standard deviation about the average of these four results which represents the best chronology has an average magnitude of only 2500 yr this small value indicates that the chronology produced is insensitive to the specific orbital tuning technique used excellent convergence between chronologies developed using each of five different paleoclimatological indicators from a single core is also obtained the resultant chronology is also insensitive to the specific indicator used the error associated with each tuning approach is estimated independently and propagated through to the average result the resulting error estimate is independent of that associated with the degree of convergence and has an average magnitude of 3500 yr in excellent agreement with the 2500 yr estimate transfer of the final chronology to the stacked record leads to an estimated error of 1500 yr thus the final chronology has an average error of 5000 yr