sediment provenance and paleoenvironmental change in the ulleung basin of the east japan sea during the last 21 kyr despite the well reconstructed paleoceanography of the late quaternary deposits in the east japan sea es provenances of terrigenous sediments and a comprehensive interpretation of their variations since the last glacial maximum remain unclear especially in regard to the mainland china and taiwan derived matter grain size conservative trace elements rare earth elements rees nd isotope and clay mineralogy of core sediments from the ulleung basin of the es were investigated for better understanding of detrital sediment provenance and transport process and then their forcing mechanisms over the last 21 kyr geochemical mineralogical multi indices in this study showed notable three phase changes in sediment provenance which can be closely related to sea level fluctuation development of the tsushima warm current as well as intermittent influence from the east asian summer monsoon climate evolution during unit 1 21 1 8 4 kyr bp when the tsushima warm current was absent in the es the paleo changjiang and the paleo huanghe mouth might be situated close to the study area and thus mainland china could have played major role in the southwestern ulleung basin sedimentation in particular the formation of rhythmic dark colored alternation in unit 1 is possibly attributable to the pulse of paleo huanghe discharge associated with centurial to millennial scale variability in the east asian summer monsoon in unit 2 8 4 7 2 kyr bp these river mouths gradually retreated to their present positions with global sea level rise leading to decreasing terrigenous sediment supply from mainland china to the study area since 7 2 kyr bp unit 3 sedimentation in the ulleung basin should still be mainly derived from mainland china meanwhile increasing chlorite kaolinite ratio but decreasing epsilon nd value revealed that terrigenous matter from taiwan might have been limitedly transported northward to the study area by the fully evolved tsushima warm current a prominent decline in chlorite kaolinite ratio together with contrast change on epsilon nd value centered at around 2 9 kyr bp 3 3 2 4 kyr bp may have been caused by the tsushima warm current suppression possibly related to the pulleniatina minimum event popularly found in the study area and nearby seas c 2014 elsevier ltd all rights reserved

sedimentary record of a fluctuating ice margin from the pennsylvanian of western gondwana parana basin southern brazil abstract the parana basin is a key locality in the context of the late paleozoic ice age lpia because of its location east of the andean proto margin of gondwana and west of contiguous interior basins today found in western africa in this paper we document the sedimentary record associated with an ice margin that reached the eastern border of the parana basin during the pennsylvanian with the aim of interpreting the depositional environments and discussing paleogeographic implications the examined stratigraphic succession is divided in four stacked facies associations that record an upward transition from subglacial to glaciomarine environments deposition took place during deglaciation but was punctuated by minor readvances of the ice margin that deformed the sediment pile tillites well preserved landforms of subglacial erosion and glaciotectonic deformational structures indicate that the ice flowed to the north and northwest and that the ice margin did not advance far throughout the basin during the glacial maximum consequently time equivalent glacial deposits that crop out in other localities of eastern parana basin are better explained by assuming multiple smaller ice lobes instead of one single large glacier these ice lobes flowed from an ice cap covering uplifted lands now located in western namibia where glacial deposits are younger and occur confined within paleovalleys cut onto the precambrian basement this conclusion corroborates the idea of a topographically controlled ice spreading center in southwestern africa and does not support the view of a large polar ice sheet controlling deposition in the parana basin during the lpia

japan sea oxygen isotope stratigraphy and global sea level changes for the last 50 000 years recorded in sediment cores from the oki ridge abstract we obtained twenty ams accelerator mass spectrometry radiocarbon dates 2 tephra layer chronologies and a planktonic foraminiferal 18 o stratigraphy for the last 50 000 years from japan sea cores from the oki ridge in this paper we report ams 14 c results that allow us to reconstruct a high resolution chronology of the cores and discuss millennial scale climate changes recorded in japan sea sediments the sedimentation rate for the site increased dramatically from the glacial stage to the holocene as a result of significant hydrological changes associated with deglaciation and global sea level rise a lighter 18 o anomaly for the planktonic foraminifers was found during the lgm last glacial maximum this shift corresponds to a freshening of the japan sea surface waters and is mainly due to a global sea level drop rather than anomalously warm ssts sea surface temperatures as previously reported our record combined with the global sea level data suggests that the lgm started about 30 kyr ago and that the salinity of the japan sea became fresher than at present the ssts during mis marine oxygen isotope stage 3 were relatively stable and global sea level was not lower than ca 80 m the surface water of the japan sea attained normal saline levels following the younger dryas cold event and reached the present day 18 o values 7 kyr ago

significance of late paleozoic fission track ages in volcanic rocks from the lavras do sul region southernmost brazil abstract this paper describes the application of apatite fission track thermochronology to four outcrop samples of the basaltic to andesitic volcanic rocks of the hilario formation located in the precambrian sul rio grandense shield in southernmost brazil the investigated unit was generated during the late stages of the neoproterozoic brasiliano pan african cycle 900 500 ma in a context of strike slip motion along ne trending structures and consequent basin inception the apparent fission track ft ages fall in the range 270 1 to 298 2 ma late carboniferous to early permian the mean confined fission track lengths range between 10 76 and 12 20 mm and the estimate for initial fission track recording below 110 c is positioned around 359 and 344 ma considering this the neoproterozoic volcanic rocks of the hilario formation were buried under at least 4 km of volcanic and sedimentary rocks resulting in thermal fading of all the original fission tracks and remained so until the late paleozoic then the investigated rocks and the whole region acted as the southern margin and source area for the paleozoic mesozoic intraplate parana basin a long lived cooling trend from the early carboniferous 359 344 ma to the permian triassic boundary ca 250 ma can be inferred from the analysis of the thermal history curves this tendency can be associated to the conjunction of uplift and denudation of this region during the carboniferous it probably reflects a response to the compressive events in the southwestern gondwanan margin in the context of the eo hercynian chanic orogeny this period in the studied region was also characterized by extensive ice caps related to the gondwanan glaciation and by lack of sedimentation with the collapse of the glaciers alluvial fan and glaciogenic sedimentation took place during the late carboniferous and early permian this cooling phase is probably recorded by the apparent ft ages a subsequent uplifting event is revealed by the analysis of the thermal history curves which show a strong inflection between 90 and 70 ma these data are here tentatively correlated with significant re arrangements of the brazilian southeastern coast such as the serra do mar and serra da mantiqueira uplifts

correlations between the classic parana and cape karoo sequences of south america and southern africa and their basin infills flanking the gondwanides du toit revisited

iron and manganese diagenesis in deep sea volcanogenic sediments and the origins of pore water colloids abstract volcanogenic sediments are typically rich in fe and mn bearing minerals that undergo substantial alteration during early marine diagenesis however their impact on the global biogeochemical cycling of fe and mn has not been widely addressed this study compares the near surface 0 20 cm below sea floor cmbsf aqueous no 3 and solid phase reactive fe distributions between two volcanogenic sediment settings 1 a deep sea tephra rich deposit neighbouring the volcanically active island of montserrat and 2 mixed biosiliceous volcanogenic sediments from abyssal depths near the volcanically inactive crozet islands archipelago shallow penetration of o2 aq into montserrat sediments was observed 5 cmbsf and largely controlled by the oxidation of organic matter dissolved fe and mn distributions in montserrat pore waters were lowest in the surface oxic layer 0 3 m fe 32 m mn with maxima 20 m fe 200 m mn in the upper 1 15 cmbsf unlike montserrat fe and mn in crozet pore waters were ubiquitously partitioned between 0 2 m and 0 02 m filtrations indicating that the pore water distributions of fe and mn in the traditionally termed dissolved size fraction are dominated by colloids with respective mean abundances of 80 and 61 plausible mechanisms for the origin and composition of pore water colloids are discussed and include prolonged exposure of crozet surface sediments to early diagenesis compared to montserrat favouring nano particulate goethite formation and the elevated dissolved si concentrations which are shown to encourage fine grained smectite formation in addition organic matter may stabilise authigenic fe and mn in the crozet pore waters we conclude that volcanogenic sediment diagenesis leads to a flux of colloidal material to the overlying bottom water which may impact significantly on deep ocean biogeochemistry diffusive flux estimates from montserrat suggest that diagenesis within tephra deposits of active island volcanism may also be an important source of dissolved mn to the bottom waters and therefore a source for the widespread hydrogenous mnox deposits found in the caribbean region

stratigraphy and reservoir potential of glacial deposits of the itarare group carboniferous permian parana basin brazil drilling in the parana basin of brazil in the mid 1980s discovered gas and condensate in the itarare group and showed that glacial deposits in brazil can contain hydrocarbons the reservoir potential of the carboniferous permian itarare group of the basin is analyzed using new subsurface data from 20 deep wells drilled in the early to middle 1980s central to the analysis was the construction of over 3000 km of cross sections based on more than 100 wells the description of more than 400 m of core and study of 95 thin sections subsurface exploration and mapping of the itarare are greatly aided by the recognition of three recently defined and described formations and four members which are traceable for hundreds of kilometers these units belong to three major glacial cycles in which the pebbly mudstones and shales are seals and glacially related sandstones are reservoirs the best sandstone reservoirs in the deep subsurface belong to the rio segredo member the uppermost sandy unit of the itarare the rio segredo member is the best petroleum target because it is overlain by thick seals and massive pebbly mudstones and shales and because it is shallower and less compacted than underlying more deeply buried sandstones this member has little detrital matrix and much of its porosity is secondary developed by carboxylic acid and co 2 generated when jurassic cretaceous basalts sills and dikes were intruded into the parana basin as gondwana broke up

geochemistry of surface sediments in the southwestern east japan sea abstract we analyzed 77 surface sediment samples collected in the southwestern east japan sea from the korea strait through the ulleung basin and the korea plateau for grain size calcium carbonate organic carbon and major na mg al fe k ca and ti and trace elements p mn sr li sc v cr co ni zn cu and pb the chemical composition of the surface sediments was found to be highly variable spatially cluster analysis of surface sediment chemical compositions indicated five major geochemical sedimentary environments basin lower slope coast and upper slope inner shelf and outer shelf continental shelf sediments were rich in shell fragments and had relict and coarse grained characteristics recent fine grained sediments were only distributed in coastal slope and basin areas concentrations of al k ca ti cr and sc were highest in the coastal and upper slope areas and decreased with water depth elemental ratios using major and trace elements indicated that coastal and upper slope detrital sediments were mixtures of sediments derived from the changjiang yangtze and nakdong rivers although the concentrations of organic carbon p mn v co ni cu and pb increased with water depth their distribution patterns indicated authigenic v cu and pb and diagenetic fe p mn co and ni origins the distribution pattern with water depth suggested that the chemical composition of surface sediment was determined by sedimentologic and geochemical processes such as the supply of detrital and biogenic materials and authigenic and post depositional diagenetic processes in sediments

phanerozoic low temperature evolution of the uruguayan shield along the south american passive margin the crystalline basement of uruguay was assembled during the brasiliano orogeny in the neoproterozoic era and was later affected by discrete tectonic activity a new multi method low temperature dataset including u th he ages from both zircon and apatite t t modelling and k ar dating of fine sericite fractions and fault gouge reveal a detailed post orogenic geological history spanning the phanerozoic eon the juxtaposition of the terranes that compose the area was achieved in the ediacaran period and post collision was marked by intense exhumation in which the crystalline basement reached near surface conditions by the early to mid palaeozoic regional subsidence promoted sedimentation in the parana basin until the permian covering and reheating much of the basement that is at present exposed afterwards deposition and volcanism were mostly confined to its current limits regional exhumation of the shield during the permo triassic exposed much of the northern portion of the basement and the south was further affected by the opening of the south atlantic ocean during the mesozoic little exhumation affected the uruguayan shield during the cenozoic as reflected in its modest topography the reactivation of inherited neoproterozoic structures influenced the development of mesozoic basins and the present day landscape supplementary material supplementary data sample locations u th he data and k ar data are available at https doi org 10 6084 m9 figshare c 3702043

nd sr isotopic and ree geochemical compositions of late quaternary deposits in the desert loess transition north central china implications for their provenance and past wind systems abstract the nd sr isotopic and ree geochemical compositions of the dishaogouwan profile in the desert loess transition between the ordos desert and the chinese loess plateau were investigated to identify the provenance of the sediments and to reconstruct the regional wind systems of the past the 87 sr 86 sr ratios of 0 7158 0 7175 nd 0 values of 8 9 to 16 8 ree values between 133 g g and 277 g g and roughly flat paas normalized ree patterns which differs from the 75 m fractions in the dishaogouwan profile this is most likely due to mineral sorting and or source features isotopic and geochemical comparisons of the dishaogouwan profile with potential sources show that 1 coarse eolian deposits resulted from wind erosion of the highlands in the adjacent west central ordos and the coarse fluvio lacustrine deposits originated chiefly from water erosion of the underlying eolian deposits in the dishaogouwan profile 2 fine particles of eolian deposits with absolute nd 0 values of 1 originated completely from the highland erosion in west central ordos and the fining of in situ coarse particles but the fine particles of the eolian deposits with absolute nd 0 values of 1 have more complex sources 3 fine fluvio lacustrine deposits were fed from the central loess plateau by water for the chengchuan and middle lower salawusu formations but for the upper salawusu formation they were significantly fed from the east central ordos desert by wind according to the source identification of the dishaogouwan profile the wind systems have been re established over the ordos and surrounding areas in the past 200 ka 1 the northwesterly was the dominant wind for eolian deposits in the dishaogouwan profile and the northeasterly simultaneously affected fine eolian deposits in certain periods the middle part of mis 6 and the lower part of mis 4 2 the summer monsoon was a predominant wind in periods during which most of the fluvio lacustrine deposits developed in the salawusu river valley but was thoroughly displaced by the cold dry northeasterly wind during the transition between mis 5 and 4 this study is helpful for further understanding the evolution of the desert loess transition and the related climate change

constraining the timing kinematics and cyclicity of mississippian early pennsylvanian glaciations in the parana basin brazil abstract ice contact deposits emplaced by late paleozoic ice age lpia glaciers are rarely exposed due to a low degree of preservation and their capping by thick glaciomarine deglaciation sequences in this paper we present new data on glacial cyclicity relative age constraints and paleoice flow interpretations for an ice contact succession of the lowermost itarare group in eastern parana basin brazil the 80 m thick ice contact complex rests over the itarare group basal unconformity and comprises four stacked informal stratigraphic units regarded as the depositional deformational record of three ice lobes advance retreat cycles glacial cycle 1 comprises a sheet of massive diamictite resting on striated pavements carved on devonian sandstones and topped by grooved fluted surfaces which indicate subglacial emplacement from a northward flowing ice lobe the glacial cycle 2 succession was deposited in a proglacial to ice marginal marine setting and subsequently deformed due to minor ice margin fluctuations of a westward southwestward flowing grounded ice lobe glacial cycle 3 is interpreted as a thick overridden push moraine composed of grounding line fan deposits capped by a subglacial diamictite emplaced by grounded ice advancing northwestward a middle visean early serpukhovian palynomorph assemblage was recorded in cycle two deposits representing the oldest late paleozoic glacial rocks in the parana basin the ice contact complex elucidates multiple waxing and waning phases of the windhoek ice sheet onto the eastern margin of the parana basin during the mississippian early pennsylvanian demonstrating that ice sheets of the early stages of the lpia were also present in the brazilian african domain of southwestern gondwana

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

the north chilean coast range an example for the development of an active continental margin analysis of extended plutons in the coast range of north chile between 25 30 and 26 35 led to the recognition of a complex magmatic and structural evolution from the upper paleozoic to the tertiary

rare earth elements of aeolian deposits in northern china and their implications for determining the provenance of dust storms in beijing this paper contributes to a better understanding of the source of dust storms in northern china and the relationship between these sources and other aeolian sediments in this region sediment samples in potential source areas were collected from the hunshandake sandy land heaven desert the loess deposits of the bashang area the mountainous basins and valleys north of beijing and from the badain jaran desert and hulunbaier sandy land fig 1 dust samples were collected in beijing during two dust storms in march 2002 and april 2006 the laboratory methods used in this study included measurements of abundance of trace elements in particular the rare earth elements rees mineral assemblages and grain size the ree contents eu and ce anomalies show clear differences between various deposits provenance is considered to be the key factor influencing ree patterns in the study areas the ree abundances and patterns indicate that the aeolian sand north of beijing such as in the heaven desert is mainly of local origin rather than from desert encroachment from the north the mineral grains carried in dust storms however are highly mixed and may come partly from local sources but mainly from distant desert regions in western china

foraminiferal records of bottom water oxygenation and surface water productivity in the southern japan sea during 160 15ka associations with insolation changes abstract analyses of the benthic and planktonic foraminiferal record were conducted to understand temporal variations in sea floor oxygenation and surface productivity during periods of dark layer deposition between 160 and 15 ka based on data from sediment core images md01 2407 water depth 932 m from the southern japan sea the dark layers in the core were classified into six types on the basis of benthic foraminiferal assemblages which reflect the nature and amount of organic material on the sea floor as well as the degree of oxygenation of bottom waters three of the dark layer types were deposited in conditions strongly associated with increased surface productivity which correlates with positive or negative peaks of summer insolation in the northern hemisphere during periods of insolation maxima summertime surface productivity was enhanced because of the inflow of nutrient rich surface waters associated with high precipitation in eastern asia caused by intensification of the east asian summer monsoon in contrast relatively sustained organic matter fluxes to the sea floor occurred during insolation minima possibly affected by active vertical mixing when the east asian summer and winter monsoons were both intensified in a given period well oxygenated bottom water environments combined with high surface productivity may have resulted in dark layer deposition because of a combination of strong wintertime water convection and increased summertime surface productivity it is likely that the organic carbon content of sediments underestimates surface productivity during depositional conditions favoring the sedimentary decomposition of organic matter

palaeomagnetic constraints on the age of deformation of the sierras australes thrust and fold belt argentina summary a palaeomagnetic study has been carried out on late palaeozoic rocks exposed in the sierras australes thrust and fold belt of buenos aires province argentina in the early permian red sandstones and clay siltstones of the tunas formation the sections sampled are exposed in the eastern parts of the belt in sierra de las tunas north and sierra de pillahuinco south more than 300 specimens were collected from 25 sites in three localities with diverent structural attitudes demagnetization at high temperatures isolated a characteristic remanence at 20 sites all the localities have a reverse characteristic remanence suggesting that the magnetization was acquired during the kiaman interval stepwise tectonic tilt correction suggests that the tunas formation in these localities acquired its magnetization during folding in early permian times palaeomagnetic poles were computed for each locality based on partial tiltcorrected remanence directions taking into account the fact that these localities are close to one another and that the rocks are all of reverse polarity a group syntectonic palaeomagnetic pole called tunas was calculated longitude 13 9 e latitude 63 0 s a 95 5 4 k 39 7 n 19 this pole is consistent with previously calculated poles from south america assigned to the early permian in age it corresponds to the early permian san rafaelic tectonic phase of the sierras australes independent geological evidence indicates that the tunas formation underwent syndepositional deformation we conclude that the tunas formation was deposited deformed and remagnetized all during the early permian

paleoceanographic implications and cyclostratigraphy of variations in well log data from the western slope of the ulleung basin east sea cyclic variations of density and gamma ray logs achieved from the two drill sites of ubgh2 1 1 and ubgh2 1 2 in the western slope of the ulleung basin were investigated to reveal their paleoceanographic implications and establish cyclostratigraphy of the well logs integration of the core log and seismic data from the two sites indicates that the sediments of the drilled intervals mostly consist of hemipelagic muds with a few sporadic mass transport deposits intercalated only in the downslope site of ubgh2 1 1 comparison with variations in sediment composition suggests that ratios of terrigeneous to biogenic materials which were modulated by orbital scale climate changes should be responsible to the well log variations the established cyclostratigraphy of the well logs based on correlation with marine oxygen isotope records indicates such climatic modulation of the sedimentation in the western slope of the ulleung basin has persisted at least since 2 6 ma consistent with the variation reported from the oki ridge

slope stability change from late pleistocene to holocene in the ulleung basin east sea japan sea abstract a wide variety of mass movement deposits prevail along the entire margin of ulleung basin overlain by a hemipelagic mud unit 1 2 m thick the boundary between the lower turbidite sequence and the upper hemipelagic mud on the basin plain is distinct and approximately coincides with the well known basin wide ash layer ulleung ash of early holocene age in the absence of significant terrigenous sediment input the lithologic change from the turbidite to hemipelagic mud may reflect physical effects of glacio marine eustatic sea level change sea level lowering during the glacial period may have generated excess pore pressure within the sediments caused by reducing hydrostatic confining pressure and facilitated triggering of the deep water slope failure by earthquakes storm waves may also have affected the uppermost slope area to induce small scale slope instabilities during the lowered sea level stand these glacial factors destabilizing the slope appear to have enhanced large scale slope failures during the late pleistocene in contrast the topmost hemipelagic mud attests to a stable slope phase associated with raised sea level in the holocene consistent with the infinite slope stability analyses calculations of the sedimentation rates based on c 14 dates of several ash layers indicate that the pre holocene turbidites on the basin plain had accumulated at an average rate of 40 cm 1000 years with a minimum recurrence interval of 50 years during the late pleistocene mass flux estimations between the slumps and turbidites suggest a predominance of the nondisintegrative mode of slope failures in the ulleung basin in each event of slope failure most of the failed mass rested on the slope as slide slump blocks and only its meager portions were deposited on the basin plain as turbidite layers

orogenic development of the argentinian chilean andes during the palaeozoic the geological development of the basement of the argentinian chilean andes during the palaeozoic is characterized by an almost continuous structural metamorphic and plutonic mobility ultrabasic magmatism occurred only in a few regions terrigenic psammopelitic sequences are widespread at all times metamorphism is mostly of low to intermediate pressure but of variable temperature late palaeozoic high pressure metamorphism only took place near the present pacific coast there are about four culminations of orogenic activity varying in space and time from the mid cambrian to the mid ordovician from the silurian to the mid devonian during the early carboniferous and at the permian triassic boundary fold structures strike in variable directions at different times on the whole the pacific margin of gondwana consolidated continuously from the shield region in the e towards the pacific during the palaeozoic

paleoenvironmental changes and depositional history of the korea tsushima strait since the lgm abstract two deep cores ssdp 102 and ssdp 105 from the southeastern inner shelves of korea were examined in order to reconstruct the paleoenvironmental history of the korea strait during postglacial sea level fluctuations the results of the lithofaces organic geochemical components foraminiferal assemblages and stable isotopes show that the korea strait was influenced in different ways by river discharges and open ocean currents according to their temporal and spatial variability the results of core ssdp 105 indicate that the southeastern coast of korea was probably a shallow coastal environment such as a shoreface or beach by about 17 5 cal ka the area remained a coastal environment that was affected by high energy conditions and partly by freshwater input during the transgressive period of 17 5 8 1 cal ka the area has changed to a modern type shelf environment influenced by the inflow of the tsushima current and by the high supply of fine grained sediments derived from the nakdong river since 8 1 cal ka meanwhile the results of core ssdp 102 taken from the nakdong river mouth reveal that the river mouth area was most likely a terrestrial or fluvial environment at least before 13 9 cal ka it then changed to the estuarine deltaic environment that was directly affected by the nakdong river between 13 9 and 7 0 cal ka and established a modern type shelf prodeltaic environment which is similar in many respects to the southeastern coast of korea after temporarily undergoing erosion between 7 0 and 6 1 cal ka

hydroclimate implications of thermocline variability in the southern south china sea over the past 180 000 yr abstract based on core top calibration the tex 86h derived temperature has been considered as representing subsurface sea temperature ssst and the difference between the u 37 k derived sea surface temperature sst and the tex 86h derived ssst can be used to reflect the depth of thermocline dot in the south china sea region jia et al 2012 we evaluated the dot dynamics in late quaternary records using this approach on paired analysis of samples from core md05 2896 7 in the southern south china sea the reconstructed dot over the last 180 000 yr 180 ka displays a shoaling trend in glacial periods which may be attributed to the strengthened cyclonic gyre by the enhanced east asian winter monsoon and walker circulation with prominent la nina like state and vice versa in interglacial periods corresponding to reduced winter monsoon with enhanced el nino like state these upper water thermal variations testify that enhanced winter monsoon was the direct cause of an uplifted local thermocline during glacial or la nina like states with strengthened cyclonic gyre due to positive wind stress curl in the southern south china sea our results provide insights into the relationship between monsoon and enso on both glacial and millennial time scales

evidence of glacial abrasion in the calingasta uspallata and western paganzo basins mid carboniferous of western argentina abstract evidence of glacial abrasion is present in the basal part of the carboniferous section of the calingasta uspallata and paganzo western argentina where subglacial and proximal glacial marine diamictites with pebbly dropstone shales constitute the dominant facies association intraformational striated pavements are exposed in the hoyada verde and leoncito formations of the calingasta uspallata basin marine invertebrate fossils levispustula zone in associated shales indicate a mid carboniferous age for both units a single layer striated boulder pavement is superbly exposed in the hoyada verde formation local a axis clast imbrication in the underlying bouldery diamictite and strong parallel striae on the flattened upper surfaces of boulders indicate a subglacial origin for the pavement paleo ice flow directions have an nne ssw strike the leoncito intraformational pavement is shaped on bioturbated fine grained sandstones with plant remains glacial striations are straight and parallel with subcircular cross sections dome like features are present in the surface which is covered in turn by a sandy bouldery diamictite four striated surfaces are present in the western paganzo basin three of them pavements at the san juan river valley loma de los piojos and agua hedionda are developed on basement rocks they contain parallel to subparallel striations nailhead striations crescentic gouges impact marks and furrows the pavements are overlain by thin up to 1 5 m laterally discontinuous diamictite beds with striated clasts some of them bullet shaped paleo ice flow directions are n ne directed an intraformational pavement is also present at the san juan river valley section it is carved on the top of the basal diamictite and exhibits furrows probably caused by subglacial soft sediment grooving the dispersion of paleo ice flow directions in the calingasta uspallata and paganzo basins indicates i regional slopes toward the north into a brackish water embayment and northwest into the open marine conditions ii glacial erosion by ice grounded below sea level and confined to the margins of the basins

the agglutinated foraminifera from the sw pacific bathyal sediments of the last 550kyr relationship with the deposition of tephra layers abstract the agglutinated foraminiferal content from the last 550 kyr record of the images core md 97 2114 chatham rise new zealand was analysed in order to detect the possible linkage existing between the composition of the grains forming the agglutinated tests and the deposition of tephras the core was collected east of new zealand about 680 km from the active taupo volcanic zone tvz located on the north island thus it contains numerous macro and microscopic tephra layers scanning electron microscopy and energy dispersive spectroscopy analyses were carried out on entire agglutinated foraminifera as well as on sectioned specimens sampled around and within the tephra layers the analyses show that the studied foraminifera built structurally complex tests picking and selecting mineral and biogenic particles on the basis of their availability and abundance in the substratum as well as their composition size and shape in most of the studied species belonging to the order textulariida the composition of the agglutinated grains does not change when the deposition of the tephra layer strongly enriched the substratum in volcanic glass shards only the species karreriella novangliae changed significantly its grain composition mostly selecting volcanic glass fragments to cover the test surface nevertheless the tephra deposition seems to influence the wall microstructure of the agglutinated tests textulariid specimens coming from the volcanoclastic layers have a thinner wall which is also characterised by a less abundant calcareous matrix with respect to the specimens sampled above or below the tephra layer we hypothesise that the volcanic ash deposition probably interfered with the normal agglutinating process by causing the development of more aggressive waters at the sea floor which in turn could have induced carbonate dissolution our observations therefore suggest that the sediment type of the substratum is not the only controlling factor in the construction of the agglutinated foraminiferal test and grain selection which appears to be species dependent

spatial and glacial interglacial variations in provenance of the chinese loess plateau the chinese loess plateau clp covers an extensive area over 440 000 km2 and provides an unprecedented terrestrial record of neogene climate however it is still unclear whether the provenance of these loess deposits is uniform or contains spatial and temporal differences here this is addressed by comparing detrital zircon age spectra of typical loess and paleosol samples from three distant sites located at the western middle and southeastern parts of the clp our results reveal that the zircon age spectra not only change between loess and paleosol layers but also vary from the western to the eastern clp at least during the last glacial cycle the discrepancies of the zircon age spectra among different sites suggest that the loess provenance of clp is heterogeneous and spatially variable although it has been suggested that the mineralogical elemental and isotopic compositions of loess deposits on clp are highly homogenous spatially and in glacial interglacial cycles

holocene influx of the tsushima current into the japan sea signalled by spatial and temporal changes in neogloboquadrina incompta distribution neogloboquadrina incompta is an optimal marker of the transitional water formed by mixing of the warm tsushima current with cold waters of the japan sea spatial and temporal changes in n incompta distribution have been analysed to reconstruct the timing and processes by which modern surface water conditions were established in the japan sea as a function of postglacial influx of the tsushima current resulting from rising sea levels the spatiotemporal distribution of n incompta suggests that transitional water formed in the eastern to southern marginal regions of the japan sea prior to the deposition of the k ah tephra 7 3 cal kyr bp and then expanded southwestward a northern cold water mass together with the cold liman current affected the southwestern part of the japan sea until 6 9 cal kyr bp which may have been a result of the weaker influence of the tsushima current during a time of lower sea level

devonian carboniferous unconformity in argentina and its relation to the eo hercynian orogeny in southern south america the devonian carboniferous contact in southern south america characterized by a sharp unconformity has been related to the late devonian early carboniferous eo hercynian orogeny the calingasta uspallata basin of western argentina and the sauce grande basin ventana foldbelt of eastern argentina have been selected to characterize this unconformity the eo hercynian movements were accompanied in western argentina by igneous activity related to a late devonian early carboniferous magmatic arc mainly exposed today along the andean cordillera this magmatic activity is partly reflected also in eastern argentina ventana foldbelt where isotopic dates suggest a thermal event also related to the intrusions present to the west in the north patagonian massif and sierras pampeanas the scarcity of lower carboniferous deposits in the stratigraphic record of southern south america suggests that the early carboniferous was a time interval dominated by uplift and erosion followed by widespread subsidence during the middle and late carboniferous the origin of the eo hercynian orogeny can be linked with the convergence between the arequipa massif and its southern extension and the south american continent its effects are best represented along the palaeo pacific margin although distant effects are discernible in the cratonic areas of eastern south america

rare earth elements as provenance indicators in north australian estuarine and coastal marine sediments rare earth elements ree in three grain size fractions of clay dominated estuarine and coastal sediments from the north australian coastline have been investigated for use as potential provenance indicators comparisons of data based on instrumental neutron activation analysis and inductively coupled plasma mass spectrometry revealed that hf digestions of zircon bearing samples resulted in unsatisfactory recovery of ree instead a relatively simple fast and safe partial digestion using hclo4 hno3 was used to extract ree mainly from clay minerals while excluding extraction of ree from zircons a comparison with published data for primary rock units within river catchments showed that the main ree systematics has been preserved in downstream clay rich sediments analysis of variance of la gd paas la yb paas and eu eu paas ratios in five areas showed that the 63 m fraction possessed the greatest discriminating power all five areas could be distinguished from each other at highly significant levels based on one or more of these ratios

post depositional redistribution processes and their effects on middle rare earth element precipitation and the cerium anomaly in sediments in the south korea plateau east sea abstract we sampled two box core sediments from the slope of the eastern south korea plateau skp in the east sea sea of japan at water depths of 1400 and 1700 m two chemical fractions of extractable hydroxylamine acetic acid and residual rare earth elements rees together with al ca fe mg mn p s as mo and u were analyzed to assess the post depositional redistribution of rees extractable fe and mn are noticeably abundant in the oxic topmost sediment layer

ree geochemistry of fine grained sediments from major rivers around the yellow sea abstract to investigate the distribution pattern and controlling factors of rare earth elements rees in riverine sediments river mouth sediments were collected at five geographically different rivers around the yellow sea two 1 m hcl leached and residual fractions and five step sequential extraction schemes the sedex method were applied to size separated sediments

sources of ree in sediment cores from the rainbow vent site 36 14 n mar a geochemical investigation was carried out on two sediment cores collected at 2 and 5 km from the rainbow hydrothermal vent site bulk sediment compositions indicate that these cores record clear enrichments in fe cu mn v p and as from hydrothermal plume fallout cave et al 2002 cave r r german c r thomson j nesbitt r w 2002 fluxes to sediments underlying the rainbow hydrothermal plume at 36 14 n on the mid atlantic ridge geochim cosmochim acta 66 11 1905 1923 sequential dissolution of the bulk sediments has been used to discriminate between a leach biogenic and oxy hydroxide component and a residual phase detrital and sulphide sulphate fractions major element data al fe ti mn mg ca si and index reveal that the hydrothermal input as recorded in the leach phase is much stronger than apparent from bulk sediment analyses alone ree patterns for the leach phase record contributions from both biogenic carbonate mimicking seawater ree patterns and hydrothermal oxy hydroxides with the latter exhibiting positive eu anomalies hydrothermal derived and negative ce anomalies seawater derived based on major element and ree data the residue contains contributions from aeolian dust input local morb material and a hydrothermal component ternary ree mixing calculations indicate that most of the ree within the residual fraction 80 is derived from hydrothermal material while detrital contributions to the ree budget as deep sea clay and volcanic debris are

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

geochemistry of rare earth elements in the mainstream of the yangtze river china abstract water suspended matter and sediment samples were taken from 8 locations along the yangtze river in 1992 the concentration and speciation exchangeable bound to carbonates bound to fe mn oxides bound to organic matter and residual forms of rare earth elements la ce nd sm eu tb yb and lu were determined by instrumental neutron activation analysis inaa the contents of the soluble fraction of rees in the river are low and rees mainly reside in particulate form in the particles the chondrite normalized distribution patterns show significant lree enrichment and eu depletion while normalized to shales both sediments and suspended matter samples show relative lree enrichment and hree depletion rees are relatively enriched in fine grained fractions of the sediments the speciation characteristics of rees in the sediments and suspended matter are very similar the amount of the five forms follows the order residual bound to organic matter bound to fe mn oxides bound to carbonates exchangeable about 65 to 85 of rees in the particles exist in the residual form and the exchangeable form is very low high proportions of residual rees reveal that rees in sediments and suspended matter are controlled by their abundances in the earth s crust carbonate fe mn oxide and organic fractions of rees in sediments account for 2 4 6 9 5 2 11 1 and 7 3 14 0 of the total contents respectively they are similar to those in the suspended matter this shows that carbonates fe mn oxides and organic matter play important roles during the particle water interaction processes by normalization to shales the 3 forms of rees follow convex shapes according to atomic number with middle ree sm eu and tb enrichment while light ree and heavy ree are depleted

climate controlled mass extinctions facies and sea level changes around the devonian carboniferous boundary in the eastern anti atlas se morocco abstract detailed sedimentological and biostratigraphical studies of successions in the eastern anti atlas se morocco focused on changing depositional environments and reconstructions of sea level changes during the late famennian to middle tournaisian the investigations cover a transect from the central maider to the easternmost and southern tafilalt regions near the moroccan algerian border the moroccan data are compared with the standard succession of the german rhenish massif and with the regional and global stratigraphic record the results testify to high frequency sea level changes including two global transgressive and anoxic events the main hangenberg event hangenberg black shale level at the top of the wocklumeria zone upper devonian vi e and the lower alum shale event at the lower middle tournaisian lower carboniferous i ii boundary regionally both anoxic intervals coincided with mass extinctions followed by rapid radiation especially of pelagic biota a significant shallowing and regression occurred just below the devonian carboniferous boundary at the northern margin of gondwana and caused the sudden n nw progradation of a large deltaic complex over 300 500 km thick siliciclastic successions filled fast subsiding synsedimentary troughs of the maider and amessoui syncline southern tafilalt correlation with the glacial phases of southern gondwana south america south africa indicates a glacial eustatic origin of sea level changes and a major sea level fall in the scale of 100 m or more coinciding with the main regressive phase of the extended hangenberg crisis interval the new results are in accord with the hypothesis of an episode of cool humid climate at the end of the devonian that allowed contemporaneous glacial buildup in high latitudes and extensive clastic discharge in the middle latitudes of nw africa

distribution of biogenic silica and quartz in recent deep sea sediments all available quartz and biogenic silica concentrations from deep sea surface sediments were intercalibrated plotted and contoured on a calcium carbonate free basis the maps show highest concentrations of biogenic silica opal along the west african coast along equatorial divergences in all oceans and at the polar front in the southern indian ocean these are all areas where upwelling is strong and there is high biological productivity quartz in pelagic sediments deposited far from land is generally eolian in origin its distribution reflects dominant wind systems in the pacific but in much of the atlantic and indian oceans the distribution pattern is strongly modified by turbidite deposition and bottom current processes

comparing contiguous high and low elevation continental margins new u th he constraints from south brazil and an integration of the thermochronological record of the southeastern passive margin of south america abstract the southeastern coast of south america is an example of the complexity of passive continental margins as it displays both high and low elevation segments despite sharing a similar pre rift geological history and structural configuration as such it is a prime candidate for investigating debated questions concerning the evolution of passive margins such as the tectonic mechanisms driving uplift their relationship to rifting and continental break up and why some margins are elevated when others are not in this contribution we present new u th he data from a low altitude portion of the south american passive margin in south brazil the sul rio grandense shield and interpret it in the context of the regional thermochronological record new results produce widespread apparent ages and reveal a complex exhumation history from the early paleozoic onwards including reheating during paleo mesozoic sedimentation for most of the study area however final exhumation was achieved at the latest during the rifting and early opening of the south atlantic ocean 135 ma to 100 ma in spite of the presence of major neoproterozoic shear zones the inherited ne sw structural framework seems not to have strongly influenced the thermochronological record the new data were integrated into a large compilation of apatite fission track and u th he results from southeast south america in order to compare regional trends and investigate possible tectonic controls in the exhumation history low elevation areas of the passive margin consistently record complex pre rift cooling histories while high elevation areas experienced significant upper cretaceous paleogene uplift associated with the reactivation of neoproterozoic shear zones because the inherited structural features of both segments are similar plate dynamics alone cannot be responsible for the variating response hence mantellic processes associated with post rift alkaline magmatism may have affected the contrasting exhumation histories this process was probably controlled by important south atlantic fracture zones

subduction mega shear systems and late palaeozoic basin development in the african segment of gondwana basins within the african sector of gondwana contain a late palaeozoic to early mesozoic gondwana sequence unconformably overlying precambrian basement in the interior and mid palaeozoic strata along the palaeo pacific margin small sea board pacific basins form an exception in having a carboniferous to early permian fill overlying devonian metasediments and intrusives the late palaeozoic geographic and tectonic changes in the region followed four well defined consecutive events which can also be traced outside the study area during the late devonian to early carboniferous period up to 330 ma accretion of microplates along the patagonian margin of gondwana resulted in the evolution of the pacific basins thermal uplift of the gondwana crust and extensive erosion causing a break in the stratigraphic record characterised the period between 300 and 330 ma at the end of this period the gondwana ice sheet was well established over the uplands the period 260 300 ma evidenced the release of the gondwana heat and thermal subsidence caused widespread basin formation late carboniferous transpressive strike slip basins e g sierra australes colorado karoo falklands ellsworth central transantarctic mountains in which thick glacial deposits accumulated formed inboard of the palaeo pacific margin in the continental interior the formation of zambesi type rift and extensional strike slip basins were controlled by large mega shear systems whereas rare intracratonic thermal subsidence basins formed locally in the late permian the tectonic regime changed to compressional largely due to northwest directed subduction along the palaeo pacific margin the orogenic cycle between 240 and 260 ma resulted in the formation of the gondwana fold belt and overall north south crustal shortening with strike slip motions and regional uplift within the interior the gondwana fold belt developed along a probable weak crustal zone wedged in between the cratons and an overthickened marginal crustal belt subject to dextral transpressive motions associated with the orogenic cycle was the formation of mega shear systems one of which falklands east africa tethys shear split the supercontinent in the permo triassic into a west and an east gondwana by a slight clockwise rotation of east gondwana a supradetachment basin formed along the tethyan margin and northward displacement of madagascar west falkland and the gondwana fold belt occurred relative to a southward motion of africa

orbital and millennial scale variations in asian dust transport path to the japan sea abstract orbital and millennial scale variations in the asian monsoon and its probable association with the dansgaard oeschger d o cycles have been demonstrated by previous studies however the origin and nature of such variations are poorly understood the japan sea is located down wind of the arid areas of the eurasian continent and thus receives significant amounts of aeolian dust consequently the hemipelagic sediments of the japan sea are expected to record a continuous aeolian dust accumulation which may provide information about the past variations in asian monsoon grain size flux and provenance of aeolian dust in the sediments were examined using two sediment cores obtained from the northern and southern parts of the japan sea in order to understand the spatial variability of asian monsoon since the silt fraction of the detrital materials in hemipelagic sediments of the japan sea is composed predominantly of aeolian dust the grain size flux and provenance of the silt fraction were examined the taklimakan desert loess plateau and siberia northeast china areas were identified as possible source areas of aeolian dust in the sediments of the japan sea based on the electron spin resonance esr signal intensity and crystallinity of quartz moreover the relative contribution of aeolian dust from each source area was estimated based on the esr signal intensity and crystallinity of quartz aeolian dust fluxes from the two source areas at the southern site were then estimated grain size and flux of eolian dust at the northern site and fluxes of aeolian dust from two source areas at the southern site show orbital scale variations in harmony with the insolation change at 30 n in june these results indicate orbital scale changes in the extent of the arid area and or frequency of dust storms in the taklimakan desert loess plateau and siberia northeast china areas and suggest that southward northward shifts of the westerly jet axis occurred together with either intensified weakened winter monsoon decreased increased winter precipitation in the siberia northeast china area or southeastward northwestward shifts of summer monsoon limit during periods of smaller larger insolation at 30 n in june in addition to these orbital scale variations millennial scale variations possibly associated with the d o cycles are observed in the grain size record of aeolian dust at the two sites based on analogy with orbital scale variations these millennial scale variations are considered to reflect millennial scale changes in the position of the westerly jet axis together with the changes either in winter monsoon intensity winter precipitation or position of summer monsoon limit our results suggest n s oscillations in the westerly jet and summer monsoon limit and changes in the intensity of the winter monsoon on orbital and millennial timescales

late pleistocene and holocene aeolian dust deposition in north china and the northwest pacific ocean abstract rates of dust deposition in the north pacific and the central loess plateau of china show a poor correlation during the last 30 000 yr although in both cases the dust was derived from deserts in northern china loess accumulation rates were high at the time of the last glacial maximum while dust flux to the north pacific was low at this time maximum dust flux to the north pacific is recorded in the mid holocene but holocene rates of loess accumulation have been low these differences are shown to reflect the different nature of the wind conditions responsible for dust transport to the loess plateau and the north pacific dust transport responsible for formation of the loess occurred mainly in the lower 1 5 km of the atmosphere and was accomplished by cold low level northwesterly winds associated with cold waves emanating from the mongolian anticyclone at present such conditions occur quite frequently in winter but during the coldest phases of the pleistocene they probably also occurred in the spring and summer long range dust transport from northern china to the north pacific requires that the dust is lifted to high levels above 3 km where it can be incorporated into the strong mid latitude westerlies strong vertical motions of the atmosphere occur most frequently in the spring when the mongolian anticyclone begins to weaken and frontal depressions move across the deserts of northern china such frontal depressions were probably more frequent during the climatic optimum of the mid holocene and during previous interglacials changes in continental aridity have probably played a minor role in controlling the magnitude of the dust flux to the north pacific

simulated variations of eolian dust from inner asian deserts at the mid pliocene last glacial maximum and present day contributions from the regional tectonic uplift and global climate change northern tibetan plateau uplift and global climate change are regarded as two important factors responsible for a remarkable increase in dust concentration originating from inner asian deserts during the pliocene pleistocene period dust cycles during the mid pliocene last glacial maximum lgm and present day are simulated with a global climate model based on reconstructed dust source scenarios to evaluate the relative contributions of the two factors to the increment of dust sedimentation fluxes in the focused downwind regions of the chinese loess plateau north pacific the model generally produces a light eolian dust mass accumulation rate mar of 7 1 0 28 g cm2 kyr during the mid pliocene a heavier mar of 11 6 0 87 g cm2 kyr at present and the heaviest mar of 24 5 1 15 g cm2 kyr during the lgm our results are in good agreement with marine and terrestrial observations these mar increases can be attributed to both regional tectonic uplift and global climate change comparatively the climatic factors including the ice sheet and sea surface temperature changes have modulated the regional surface wind field and controlled the intensity of sedimentation flux over the loess plateau the impact of the tibetan plateau uplift which increased the areas of inland deserts is more important over the north pacific the dust mar has been widely used in previous studies as an indicator of inland asian aridity however based on the present results the interpretation needs to be considered with greater caution that the mar is actually not only controlled by the source areas but the surface wind velocity

the development of middle rare earth element enrichments in freshwaters weathering of phosphate minerals abstract many phosphatic minerals of biogenic authigenic and diagenetic origin are distinguished by rare earth element ree compositions which have a well developed middle rare earth element mree enrichment defined by a gradual increase in the shale normalized ratios of ree toward the middle of the ree series la to lu also the ree composition of dissolved matter in the waters of the amazon fly and sepik rivers as well as other river lake and ground waters have well developed mree enrichments the development of mree enrichments was studied through a series of leaching experiments using river bank sediments from the amazon fly sepik and mississippi rivers a well characterized phosphate mineral rich shale with a pronounced mree enrichment in its bulk composition was also leached in order to better assess the relationship between the weathering of phosphate minerals and the formation of mree enriched solutions the two leaching solutions per sediment consisted of filtered lake water at ph 5 and the same water adjusted to ph 2 leaching experiments with the four river sediments result in extensive fractionation whereby the ree compositions of the solutions develop mree enrichments from starting sediments that show no mree enrichments the ph 2 leachates have much higher concentrations of the ree and more fully developed mree enrichments than do the ph 5 leachates the mree enrichments at ph 2 usually form within an hour of starting the experiments the phosphatic shale results show that there is preferential release of large amounts of mree at ph 5 as well as at ph 2 demonstrating the weather ability of the phosphatic minerals at phs of natural freshwaters the sepik river ph 5 experiment also shows significant mree enrichment under near neutral conditions the development and retention of the mree enrichments in the leaching solutions is accompanied by an increase in dissolved phosphate concentrations although the magnitudes of the mree enrichment do not directly correlate with the percent of phosphate released the experimental data suggest that the preferential dissolution of phosphatic minerals during weathering can result in extensive ree fractionation between bulk river sediment and water leading to freshwaters with mree enrichments

an abrupt shift in dust source on the chinese loess plateau revealed through high sampling resolution osl dating abstract the source of dust that forms the extensive deposits of loess exposed on the chinese loess plateau is highly debated in particular it is not clear whether sources can change abruptly within individual loess units or whether local influences on source can override the influence of far travelled components high vertical sampling resolution 10 40 cm optically stimulated luminescence osl dating of sediments on the loess plateau in china has been successful in providing detailed independent age models for loess accumulation here osl behaviour is used to infer a shift in loess sediment source during the last glacial period osl dating procedures have often utilised the widely applied single aliquot regeneration sar protocol on quartz grains detailed sar osl dating of the last 45 ka of sedimentation at beiguoyuan section on the north of the loess plateau demonstrates anomalous and statistically significant age increases and scatter in age estimates in samples from a c 2 5 m unit at about 20 ka compared to samples above and below many of these samples also fail internal dose recovery tests and show anomalous luminescence signal properties deconvolution of osl decay curves into first order components reveals that many of the age overestimating samples have a significant ultrafast component this behaviour is restricted to the 2 5 m segment and is only likely to be uncovered using high sampling resolution luminescence analysis combined with heavy mineral grain size and geochemical evidence this suggests that the source of material in this unit abruptly shifted at the last glacial maximum potentially to a local source rather than well mixed and recycled multiple distant sources as appears to be the case at other times at the site and other studied sections on the loess plateau the environmental causes of this source shift may be tied to abrupt climate change during the last glacial maximum and demonstrate the highly dynamic nature of the locations of dust generation during the last glacial period the change in source also adds complexity to standard climate proxy analyses of loess using sediment properties

provenance of late quaternary sediments on the southwestern slope of the ulleung basin east japan sea the provenance of fine grained sediments deposited since the late quaternary was recovered from drill site ubgh2 1 1 on the southwestern slope of the ulleung basin east japan sea based on geochemical analyses including rare earth elements rees the fine grained sediments could be interpreted as mixtures of sediments from china via various pathways and sediments discharged from the nakdong river nrs a comparison of variations in ree fractionation factor with marine isotope stages miss indicated that the provenance of the fine grained sediments on the southwestern slope of the ulleung basin was controlled by global eustatic sea level change during glacial periods most of the fine grained sediments were supplied via the atmospheric pathway by an intensified east asian winter monsoon and sediments from chinese rivers crs transported into the ulleung basin through the korea strait were limited due to the morphological characteristics of the korea strait and low sea level during interglacial periods the crs transported into the ulleung basin through the korea strait increased with sea level rise and eolian dust inputs decreased due to attenuated east asian winter monsoon simultaneously nrs also should have been deposited when sea level was higher than 40 m relative to present sea level during mis 1 and mis 5 in particular during mis 1 signals of nrs were revealed since 11 ka thus it can be suggested that the present coastal current system around the southeastern coast of korea became established by around 11 ka

rb sr geochronology of granitoid rocks from the pampean ranges argentina a reconnaissance rb sr geochronological investigation of granitoid rocks from the pampean range provides a framework whereby four culminations of igneous activity are delineated granitoids emplaced prior to 500 ma pre and synkinematic bodies ca 475 ma late kinematic bodies and ca 440 and 340 ma post kinematic bodies a number of the post kinematic granitoids have disturbed sr isotope systematics which is related to the formation of microcline megacrysts the carboniferous granitoids are distinguished by their high initial sr ratios i e 0 710 a feature compatible with an origin involving reworking of upper crust or crustal contamination there appears to be no systematic e w migration of granitoid emplacement during the ca 300 ma evolution of the basement rocks in the pampean ranges

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

alkenone temperature estimates for the east sea during the last 190 000 years abstract the late quaternary records of alkenone based sea surface temperature sst from a core located in the western margin of the east sea japan sea showed that the estimated temperature fluctuated greatly the variability being consistent with orbital scale global climate records during the period of marine isotope stage mis 6 the alkenone temperatures were low 7 10 c whereas during mis 5 5 the temperature increased rapidly up to 21 c during the entire period of mis 5 the temperature decreased from 21 c to 13 c then the temperature fluctuated between 10 c and 15 c during miss 4 and 3 after that it continued to fluctuate between 15 c and 17 c variation in the east sea sst is considered to be closely related to changes in the east asian monsoon system and seawater transport by the tsushima warm current the glacial surface cooling could be associated with the strong winter monsoon and or weakened summer monsoon in east asia during the glacial period when the sea level was low the influx of warm water was restricted and this might have enhanced the lowering of the surface temperature these conditions most likely caused significant changes in surface water circulation a basin scale cyclonic gyre might have occurred in the east sea without the development of the subpolar front during the interglacial period the surface warming seems to be related to the intensified summer monsoon system the high stand of the sea level and climate change most likely caused the development of cyclonic and anti cyclonic gyres in the north and south respectively and the subpolar front in the central part of the sea

a provenance study of the paleozoic ventania system argentina transient complex sources from western and eastern gondwana abstract the u pb and lu hf isotopic analyses of the different sedimentary sequences of the ventania system an old paleozoic orogenic belt exposed in the southern region of the rio de la plata craton in the province of buenos aires argentina provide new evidence for the understanding of the tectonic evolution of the western sector of the gondwanides mountain belt these ranges formed as result of the late paleozoic collision of the patagonia terrane against the continental margin of gondwana the provenance analysis together with the sedimentary paleocurrents confirm a dominant source from the tandilia system a paleoproterozoic mountain belt formed during the amalgamation of the rio de la plata craton at about 1800 2200 ma and incorporated to western gondwana during the brasiliano orogeny at 550 530 ma the local dominant source at the base of the early paleozoic changed to more distant supplies toward the top of the sequences when an increasing participation of detritus from first cambrian 560 520 ma zircons from the pampean orogen and later on ordovician 480 460 ma zircons from the famatinian orogen is recorded the detrital zircon patterns and the maximum age of the units shed light on some previous discrepancies in the early paleozoic stratigraphy the balcarce formation an early paleozoic sedimentary cover of the tandilia metamorphic and igneous basement shows striking differences when compared with the new data from the ventania system the two data sets reveal different sources for the two regions the late paleozoic foreland basin deposits mark an abrupt change of 180 in the paleocurrent directions in the petrographic composition of the sediments and in the provenance of detrital zircons these data indicate a southern provenance with the first evidence of carboniferous and permian magmatic zircons the oldest archean zircons together with the finding of clasts with archeocyathids support the provenance from patagonia which was derived from eastern gondwana the u pb ages of the ash fall tuffs in the tunas formation confirm the early permian age of the eurydesma fauna in the ventania system the u pb data together with the lu hf isotopic data enhance the comprehension of the tectonic evolution of the ventania system as part of the larger gondwanides belt that amalgamated to western gondwana during late permian times with some independent pieces derived from eastern gondwana

carbonate chemistry of the sea of japan the alkalinity and total co2 data were collected during the kuroshio edge exchange processes marginal sea studies expedition july 28 to august 5 1992 in the sea of japan the concentrations of normalized alkalinity nta ta 35 s s represents salinity and normalized total co2 ntco2 tco2 35 s in the deep water are fairly low relative to that of the northwest pacific ocean indicating relatively little caco3 dissolution and organic carbon decomposition in the subsurface waters of the sea of japan a benthic front between the deep water and the bottom water can be characterized by discontinuities of dissolved oxygen and ntco2 at about 2000 m the bottom water is quite homogeneous with 0 1 0 05 c s 34 07 0 005 dissolved oxygen 215 5 mol kg nta 2373 5 mol kg and ntco2 2297 5 mol kg the inorganic carbon organic carbon ratio shows that about a 15 increase in ntco2 of the deep water is contributed by the inorganic caco3 dissolution this is rather low compared to the open pacific ocean values of 30 40 the degrees of saturation with respect to calcite and aragonite show that the deep water is undersaturated with respect to calcite below 1300 m the water below 300 m is undersaturated with respect to aragonite excess co2 is present from surface to bottom confirming rapid turnover of the sea of japan deep water 100 years turnover time reported previously based on tritium freons 11 12 and 226ra data previous age estimation of 300 years for deep waters based on 14c data was inconsistent with the above results recalculation based on proper prebomb 14c value gives an age of about 120 years for deep sea of japan water overall the sea of japan contains 3 1 0 5 1014 g excess carbon

correlation between climate events in the north atlantic and china during the last glaciation episodes of massive iceberg release heinrich events 1 3 into the north atlantic ocean during the last glaciation were associated with recurring episodes of unusually cold north atlantic surface water bond cycles 4 and cold air temperatures over greenland dansgaard oeschger events 5 6 four of the youngest of these cold events have also been reported in climate records from sites outside the north atlantic region7 but until now the entire suite has been identified only in north atlantic marine sediments greenland ice core records and tentatively in french lake sediments8 here we examine grain size data from chinese loess and intercalated accretionary palaeosols of last glacial age for evidence of similar climate signals remote from the north atlantic region we see grain size maxima with ages that match those of the last six heinrich events which we interpret as an indication of the changing strength of the east asian winter monsoon which largely controls the transport and deposition of central asian aeolian dust thus it seems that these heinrich events have left their signature in the chinese loess record this is consistent with simulations of the glacial climate9 which imply that the climates of the north atlantic and china were linked by the effect of westerly winds

discrimination of sediment provenance using rare earth elements in the ulleung basin east japan sea abstract in order to discriminate the origins of ulleung basin east japan sea sediments using rare earth elements rees sediments from 15 box cores and one piston core collected in the shelf slope and basin were analyzed for major elements al fe ca and mn and rees the major sedimentary components in this basin were presumed to be detrital materials from land even in the basin sediments based on al and organic contents carbon and opal post depositional recycling processes involving fe and mn were identified in the basin sediments thus the ce anomaly and the fractionation factors of light rees lrees and middle rees mrees relative to heavy rees hrees could not be used as provenance indicators in the deep basin sediments 2000 m of water depth based on a feasibility check using their covariation with fe and mn for the shelf slope and basin b sites near islands water depths of 1200 1800 m regions the eu anomaly lreen hreen and mreen hreen could be successfully used to discriminate possible provenances including nakdong river sediments nrs chinese river sediments crs ulleungdo volcanic rocks uvr and dokdo volcanic rocks dvr from the provenance indicators slope as well as the shelf sediments called the korea strait shelf mud kssm in the ulleung basin can be regarded as mixtures of nrs and crs with decreasing portions of nrs in the kssm with distance from the nakdong river basin b sediments were mixtures of uvr or dvr and crs these findings can be explained if sediments discharged from the nakdong river were transported and deposited kssm northward within the strong coastal front in normal periods and if sediment flumes from summer floods flowed out across the coastal front were carried with the tsushima warm current and then deposited in the slope area this study indicated that crs were very important detrital sediments and that ree compositions can be successfully used as a provenance indicator in even hemipelagic sediments close to land