rapid releases of metal salts and nutrients following the deposition of volcanic ash into aqueous environments deposition of volcanic ash into aqueous environments leads to dissolution of adsorbed metal salts and aerosols increasing the bioavailability of key nutrients volcanogenic fertilization events could increase marine primary productivity leading to a drawdown of atmospheric co2 here we conduct flow through experiments on unhydrated volcanic ash samples from a variety of locations and sources measuring the concentrations and fluxes of elements into de ionized water and two contrasting ocean surface waters comparisons of element fluxes show that dissolution of adsorbed surface salts and aerosols dominates over glass dissolution even in sustained low ph conditions these surface ash leachates appear unstable decaying in situ even if kept unhydrated volcanic ash from recent eruptions is shown to have a large fertilization potential in both fresh and saline water fluorine concentrations are integral to bulk dissolution rates and samples with high f concentrations display elevated fluxes of some nutrients particularly fe si and p bio limiting micronutrients are released in large quantities suggesting that subsequent biological growth will be limited by macronutrient availability importantly acidification of surface waters and high fluxes of toxic elements highlights the potential of volcanic ash leachates to poison aqueous environments in particular large ph changes can cause undersaturation of caco3 polymorphs damaging populations of calcifying organisms deposition of volcanic ash can both fertilize and or poison aqueous environments causing significant changes to surface water chemistry and biogeochemical cycles

geochemistry and provenance of the middle ordovician austin glen member normanskill formation and the taconian orogeny in new england the austin glen member of the upper middle ordovician normanskill formation is a sandstone shale ysch succession deposited in the foreland of the taconian orogen petrographic major and trace element and nd pb isotopic data provide substantial constraints on its provenance lack of k feldspar and paucity of plagioclase in addition to the dominance of sedimentary rock fragments indicate that the source was dominated by recycled sedimentary components major and trace element data support this conclusion and indicate that the provenance of both shales and sandstones was the same no evidence of an ophiolitic or volcanic component was observed interpretation of nd isotopic characteristics are complicated by a partial resetting of the nd isotope system at about the time of sedimentation but indicate that the provenance of the austin glen member had a long term history of light rare earth element lree enrichment average tdm 1a8 ga furthermore nd isotopic compositions are extremely homogeneous end 8a1 0a6 1 s d n 23 at 450 ma the approximate depositional age indicating either a single source or very well mixed sources 207pb 204pb ratios are variable but within the range of pb isotopic compositions typically described as grenvillian the range of 207pb 204pb is greater than expected for the range of 206pb 204pb and suggests an additional component of pb possibly introduced during diagenesis the immediate source of the austin glen member may have been the accretionary prism that developed as older sediments of the laurentian margin were scraped off the basin oor incorporated within the accretionary prism and shed into the basin no evidence indicating the arrival of an undifferentiated island arc or continental fragment during the taconian orogeny has been found the data acquired during this study can be explained almost exclusively by grenville province source components but with possible additional contributions from older laurentian terranes and late proterozoic rift volcanics that are not readily quanti ed but likely to have been minor accordingly we conclude that the taconian orogeny in new england involved either 1 a continental arc that involved exclusively laurentia 2 collision of a continental block with identical geochemical characteristics as laurentia or 3 essentially no detritus from any exotic colliding block island arc or continental fragment reached the foreland basin at the time of austin glen deposition

control actions of sedimentary environments and sedimentation rates on lacustrine oil shale distribution an example of the oil shale in the upper triassic yanchang formation southeastern ordos basin nw china abstract oil shale is an important form of unconventional resources it is significant to determine the control factors on oil shale distribution abundant oil shale resources are hosted in the member chang 7 3 ch7 3 triassic yanchang formation in southeastern ordos basin nw china this study was conducted to investigate the sedimentary environment distribution and organic matter source of the ch7 3 oil shale by a combined study of outcrops core data organic and element geochemical indices the controlling factors of the oil shale distribution were determined by an analysis of sedimentary environments and geochemical features of the oil shale sedimentary facies analysis based on outcrops and core data indicated that the ch7 3 oil shale was deposited in lacustrine delta environments warm and moist climates and reducing conditions indicated by major and trace elements were favorable to organic matter production and preservation rock eval pyrolysis showed that the organic matter of the ch7 3 oil shale is from both lacustrine phytoplankton and terrigenous higher plants the organic matter from terrigenous higher plants was probably transported into the deep lake by gravity flows sedimentary facies and la yb n values show that the spatial distribution of oil shale was controlled by sedimentary environments and sedimentation rates in the deep lake area near to delta turbidite fan deposition systems terrestial organic matter input was bounteous and sedimentation rates were moderate which were beneficial to organic matter accumulation and preservation providing favorable conditions for oil shale formation in delta turbidite fan deposition systems high sedimentation rates led to organic matter dilution in the deep lake area far from delta turbidite fan deposition systems sedimentation rates were relatively low and organic matter was easily degraded in addition only lacustrine organic matter input with no terrestial organic matter input inhibited organic matter enrichment

the role of event beds in the preservation of organic carbon in fine grained sediments analyses of the sedimentological processes operating during deposition of the whitby mudstone formation toarcian lower jurassic preserved in northeast england abstract geologists have recently observed that source rocks commonly contain a wide variety of microfabrics including diminutive ripples and burrows the existence of these fabrics challenges the assumption that persistent bottom water anoxia and low energy conditions are necessary prerequisites for enhanced organic carbon preservation in these units in order to enhance our understanding of the depositional and diagenetic processes responsible for organic carbon preservation in these strata the lower jurassic whitby mudstone formation which contains mudstones with up to 14 2 total organic carbon has been investigated using optical electron optical and geochemical methods four thinly bedded mudstone lithofacies were identified a silt bearing clay rich mudstones b clay rich mudstones c clay calcareous nannoplankton and organic carbon bearing mudstones and d cement rich mudstones internally individual beds are typically sharp based and normally graded they are either laminated partially bioturbated or homogenized where depositional fabrics are preserved pellets silt lags ripple lamination shell pavements wave enhanced sediment gravity flows of fluid mud and organo minerallic aggregates have been observed the presence of up to 14 2 toc in units that are sharp based and normally graded suggests that mass flows possibly generated by storms likely influenced sedimentation during deposition of these mudstones the abundant organo minerallic fabrics in these units indicates that at least some of the organic carbon was delivered to the seafloor as marine snow aggregates that likely formed in the water column following phytoplankton blooms homogenization of bed tops indicates that between sediment delivery episodes an infauna was able to colonize the seafloor implying that the bottom waters were at least partly oxygenated during these intervals these fabrics suggest that during deposition of the whitby mudstone formation organic carbon was being preferentially preserved below regions of high primary organic production the close association between sharp based graded beds and organo minerallic aggregates indicates that large volumes of organic carbon were delivered episodically to the seafloor and that conditions at the sediment water interface were episodically dynamic here organic carbon is likely to have been preferentially preserved because the frequency of depositional events was sufficiently high to minimize both oxidant diffusion into the sediment and organic carbon mineralization while bottom water anoxia may have developed during the phytoplankton blooms it was unlikely to have been persistent because the microfabrics present indicate that there was sufficient time and oxygen available for an infauna to disrupt the sediment between deposition events

chemical characteristics and acid drainage assessment of mine tailings from akara gold mine in thailand acid mine drainage amd is a great concern in many abandoned mines because of its adverse effect on the environment in mining processes many kinds of wastes are produced these wastes may become eventually sources of environmental degradation the focus of this study is the geochemical characterization of the end processed tailings generated by akara gold mine the biggest gold mine in thailand tailing samples were systematically collected for analyses of chemical and mineralogical compositions as a result their quantitative chemical analyses are slightly different from place to place but mineral components cannot be clearly differentiated for instance it may be assumed that the end processed tailings which were a mixture between high and low grade concentrates would have similar mineral components however the little variation of chemical composition may be caused by the ore refining processes that are somehow varied in proportion to chemical additives alkali cyanide and quick lime in particular in addition clay composition in ore bearing layers may also influence alumina content of tailings accordingly distribution of the tailings is not related to depth and distance of the tailing storage pond because the disposal has sped them over the pond during operation total heavy metals of the tailing samples were analyzed on the basis of the epa 3052 method consequently the most toxic elements e g co cu cd cr pb ni and zn were found falling within the standard of thailand soil quality standards for habitat and agriculture only mn appears to have higher content than the standard in addition leaching tests proved that these tailings contain low metal concentrations as a result at ph 2 mn can leach out exceeding the thailand surface water quality standard for agricultural mn 1 ppm and the thailand industrial effluent standard 5 ppm although leachate at ph 4 and neutral conditions contains lower mn than the industrial effluent standard it still exceeds the surface water quality standard interestingly pb can be leached out exceeding both standards 0 2 ppm for the industrial effluent standard and 0 05 ppm for the surface water quality standard for ni leaching its concentration is lower than the industrial effluent standard at all ph conditions but still exceeds the surface water standard at ph 2 and 4 this information should be taken into consideration for further environmental monitoring acid generating potential of the tailings was estimated using acid base accounting aba and net acid generation nag tests the results of aba and nag tests show that the tailing samples contain a high amount of sulfur however they also contain high acid neutralization capacity consequently these tailings may not have potential to generate acid drainage in the other words they can be classified as a non acid forming naf material however since these tailings contain some heavy metals e g ni mn and pb that are observed in leachates exceeding the standards at low ph the amd conditions may lead to heavy metal release therefore prevention of oxidizing process and dissolution should be considered with great care in addition mn and pb can also be leached at neutral conditions barrier of air and water clay layer for example should be placed over the tailings pound before covering by topsoil for re vegetation growing native grass is recommended for stabilization of the surface and reducing erosion rate monitoring of water quality should also be carried out annually

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

black shale deposition and faunal overturn in the devonian appalachian basin clastic starvation seasonal water column mixing and efficient biolimiting nutrient recycling integrated geochemical data suggest that black shale deposition in the devonian geneseo formation of western new york was initiated by the coincidence of siliciclastic starvation and the intensification of seasonal water column stratification and mixing once established however black shale deposition was maintained through efficient recycling of biolimiting nutrients which enhanced primary productivity recycling efficiency was achieved through a positive feedback loop of oscillating benthic redox conditions that enhanced n and p regeneration from sediments sustained high primary productivity by returning nutrients to the photic zone during mixing and ensured a downward flux of organic matter that drove or enhanced the episodic development of benthic anoxia during stratification this feedback was ultimately disrupted by rising siliciclastic influx which diluted organic matter and restored benthic redox stability the abrupt overturn of diverse long standing appalachian basin marine communities may have been the result of trophic resource destabilization during geneseo deposition

lacustrine sedimentation processes and patterns during effusive and explosive volcanism challis volcanic field idaho abstract lacustrine deposits in the eocene challis volcanic field accumulated in a deep lake bordered by steep ranges volcanic and nonvolcanic sediment was transported into the lake via a major dispersal system from the north high density turbidity currents transported this sediment throughout the lake system paleozoic rocks in the adjacent ranges were secondary sediment sources this sediment was trapped along the shoreline and only a small fraction was transported offshore by turbidity currents the frequency of turbidity currents varied with changes in eruption style thus turbidite accumulation patterns are a faithful record of changes in volcanic activity and associated landscape processes effusive volcanism that characterized the early activity in the challis volcanic field produced little sand size sediment and had little impact on lacustrine sedimentation patterns relatively slow settling from suspension characterized lake sedimentation during this time turbidity currents were infrequent the resulting accumulation pattern is a single sheet of turbidite sandstone encased in thick bedded mudrock initial eruptions at the van horn peak cauldron complex altered sedimentation patterns dramatically by increasing the frequency of turbidity currents a turbidite ramp prograded into the study area marking a major increase in sedimentation rate sediment composition and turbidite accumulation patterns record changes in landscape processes syneruption deposits are stacked turbidite sheets early turbidites contain mostly sediment derived from the fresh pyroclastic material the proportion of sediment from pre eruption sources increases upward through the stacked sheets recording a change in sediment sources at the end of the syneruption period ramp growth continued through this part of the period although at a much slower rate

depositional environment of oil shale within the second member of permian lucaogou formation in the santanghu basin northwest china abstract the non marine santanghu basin in northwest china hosts one of the richest and thickest permian lacustrine source rock intervals in the world conventional oil in jurassic sandstone reservoirs and tight oil in the tuffaceous permian tiaohu formation were sourced from mudrocks in the underlying second member of lucaogou formation which also have tight oil potential proved by recent commercial discoveries based on inorganic and organic geochemistry organic petrography and stable isotope geochemistry the depositional environment and the tight oil potential of the second member of permian lucaogou formation were investigated the data imply a gradual evolution of the depositional environment from a stratified saline to a freshwater lake the succession can be subdivided into a lower middle and an upper unit each characterized by decreasing water salinity high bioproductivity has been caused by the bloom of algae and photosynthetic cyanobacteria water column stratification accelerated the activity of methanothrophs as indicated by low 13c values of hopanes biomarker composition provides evidence for decreasing contributions of cyanobacteria to the biomass and increasing abundance of prasinophytae compared to other algae with decreasing salinity enhanced terrigenous organic matter input appeared during periods of high freshwater inflow low total organic carbon toc contents in the lower unit are most likely caused by rapid sedimentation rate high bioproductivity and excellent preservation conditions resulted in high toc contents in the middle unit terrigenous organic matter input increased together with fresh water inflow in the upper unit resulting in high toc values during periods of possibly low sedimentation rates in a deep water column the samples of the second member exhibit a good to very good potential to generate conventional oil high toc and extractable organic matter yields together with the thickness of the fine grained sediments show that the middle and upper units of the second member of lucaogou formation hold significant tight oil potential mineralogical composition of this dolomite rich shale with respect to abundance of brittle minerals including quartz and carbonates and rare clay testifies a good tight oil potential

organic geochemistry and petrography of lower cretaceous wealden black shales of the lower saxony basin the transition from lacustrine oil shales to gas shales abstract ninety seven wealden black shale samples from three wells in the lower saxony basin have been studied by organic geochemical and organic petrographical methods to determine their maturity organic facies and depositional environment the maturities of the three wells range from early mature ex a late to postmature ex c to overmature ex b as determined by vitrinite reflectance measurements diamondoid ratios and other geochemical maturity parameters ex c and ex b show distinct petrographic features related to oil generation and migration in particular the occurrence of dispersed solid bitumen replacing initial type i kerogen suggests a formerly active petroleum system structural and textural differences between early mature alginites and solid bitumen in postmature to overmature samples show an alteration of the pore system with increasing maturity a freshwater depositional environment is indicated by widespread occurrence of botryococcus algae and other small alginite particles predominating in the immature well these alginites are absent in the more mature gas shales of wells ex c and ex b geochemical evidence of algae and phytoplankton in general is provided by numerous biomarker parameters while the occurrence of carotane in some samples indicates events of increased salinity although no hypersaline conditions are inferred due to very low gammacerane indices increased amounts of vitrinite and inertinite in samples of ex b suggest locally significant terrigenous input of organic matter for some periods during wealden shale deposition high sulfur organic carbon ratios provide evidence for sulfate rich waters and partly anoxic bottom water conditions while the lower mature lacustrine source rocks generate paraffinic waxy oils gas and condensates are produced at post mature stages furthermore maturity distribution maps from 3d numerical petroleum systems modeling reveal substantial differences in respect to petroleum generation

controls on organic matter accumulation in the triassic chang 7 lacustrine shale of the ordos basin central china abstract the triassic chang 7 formation is a rich lacustrine source rock in the ordos basin central china petrographic and geochemical analyses were performed in order to research the mechanism of organic matter om enrichment in the chang 7 shales bulk geochemical data indicate that the om rich shales were formed in a fresh and brackish water which is not usually the case for high toc total organic carbon content sediments therefore there must be some special conditions favorable for om enrichment in chang 7 shales petrography and element geochemistry show that the chang 7 om rich shales are abundant in om enriched laminae framboidal pyrites collophanes and some elements including iron fe diphosphorus pentoxide p2o5 copper cu vanadium v molybdenum mo and uranium u high bio productivity algae blooming and anoxic depositional environments are critical for om enrichment as the organic carbon contents increase the fe p2o5 cu v mo and u element contents increase as well and the ratios of u th and v v ni are growing many geochemical data demonstrate that the water was oxic while the environment under the sediment water interface was anoxic as a result of a high organic supply that sufficiently consumed oxygen taking into account the geological settings and our previous studies we propose that the frequent volcanic events and hydrothermal activity caused by the collision of the north china landmass with the yangtze landmass and consequential formation of the qingling mountains had a significant role in the om enrichment in the fresh and brackish lacustrine shales deposition of volcanic ash into aqueous environments might lead to the increase of some key nutrients such as fe and p2o5 which might enhance primary bio productivity new evidence for hydrothermal activity the reddingite was demonstrated in this study not only can the hydrothermal activity provide elements necessary for life but is also favorable for formation of anoxic settings the deposition of the chang 7 lacustrine om rich shales can be explained using the high bio productivity driven model which is related to volcanic events and hydrothermal activity as a consequence of regional tectonic movements an anoxic depositional setting is beneficial for om preservation and slow sedimentation rates in the deep lacustrine environments are favorable for om enrichment

speculations on the mesozoic plate tectonic evolution of eastern china several orogenic belts transecting eastern china are the sites of former convergent plate margins although there have been varying views on the collisional framework of individual continental blocks styles of convergence at these zones and the timing of respective collisions a tectonic study of eastern china mongolia and the southern soviet far east indicates the collision of the south china block with a combined north china northeast china fold zone block in the late triassic early jurassic their collective suturing to eurasia in the late jurassic early cretaceous followed by the sikhote alin japan block in the mid to late cretaceous the evidence is as follows 1 a linear belt of late triassic early cretaceous granites and granodiorites trends east from the qinlingshan through the dabieshan to the huaiyang massif ophiolites flysch subduction zone melange a paired metamorphic belt indicating north dipping subduction and marine strata of carboniferous to late triassic age from the qinlingshan define the suture between the north and south china blocks 2 a sinuous belt of ultramafics blueschists silicic to intermediate magmatism and west and north vergent folds and thrusts trend from the west margin of the ordos basin through central inner mongolia and along the east great khingan range to the amur river coupled with a mid jurassic early creataceous unconformity a suturing of eastern chinese blocks to eurasia along this zone is suggested 3 a fold and thrust belt with ultramafics flysch blueschists and subduction zone melange along the ussuri river in northeast china indicates the suturing of the sikhote alin japan block to eurasia along a west dipping subduction zone in the mid to late cretaceous similarly a tectonic study of southern china and southeast asia has revealed a complex regional mosaic of suture bounded terrains which nucleated about the eastern western and southern margins of the yangtze craton during the late triassic and early jurassic the evidence is as follows 4 a north south trending belt of ophiolites blueschists calc alkaline volcanics and subduction zone melange including granites granodiorites and strongly deformed marine strata all of late triassic age exposed in the longmenshan of sichuan merge with the kekexilishan ophiolite zone into the ailaoshan tengtiaohe ophiolite and blueschist belt in central yunnan along which the songban ganzi complex and the shan thai malaya block join the craton and 5 a southeastern prolongation of the ailaoshan tengtiaohe belt bifurcates into the southeast trending konvoi zone of northern vietnam and the north south trending pak lay luang prabang zone of laos and eastern thailand zones of ophiolite calc alkaline volcanics and strong late triassic deformation they separate the indosinia and shan thai malaya blocks from the craton respectively these findings differ significantly from previous interpretations of a late paleozoic consolidation of south eastern asia as well as disputing the existence of a true pangea

sedimentary organic matter record of early cretaceous environmental changes in western liaoning province ne china abstract the abundance and composition of organic matter and the 13 c compositions of some specific individual compounds were analysed in sediments collected from an excavated profile of the early cretaceous yi xian formation in liaoning province ne china in order to provide organic geochemical information on palaeoclimate and environmental changes the distribution of n alkanes varies steadily through the profile with long chain n alkanes dominating in the lower and upper sections and medium chain length n alkanes dominating in the middle section of the profile the 13 c values of n alkanes hopanes and steranes show similar upward positive trends through the profile suggesting that these compounds originated from the same source material and also reflect consistent changes in the environment of the sedimentary basin the c 24 17 21 seco hopane was only detected in the lower and middle sections of the profile and has a more positive carbon isotopic composition by about 3 7 6 7 than that of associated n alkanes hopanes steranes and c 30 8 14 seco hopane this implies that the c 24 17 21 seco hopane had a different origin possibly connected with the volcanic ash deposits and massive vertebrate remains reconstruction of the 13 c composition of atmospheric co 2 based on plant derived c 29 and c 31 n alkanes shows a change from 10 to 3 from the bottom to the middle of the profile this upward positive excursion through the profile is consistent with the worldwide variation of atmospheric co 2 during the early cretaceous and indicates an upward warming trend likely related to globally intensified volcanic activity

petroleum generation an easy and widespread process in hydrothermal systems an overview abstract the conversion of organic matter to petroleum products by hydrothermal activity is an easy process occurring in nature in many types of environments geologically immature organic matter of marine sediments has been shown to be altered to petroleum products by this process in the guaymas basin escanaba trough bransfield strait and atlantis ii deep and this process probably occurs elsewhere in active sedimented rift systems contemporary organic detritus and or viable microorganisms are also converted in part to petroleum like products when they become entrained by turbulent mixing into hydrothermal vent waters resulting in their instantaneous hydrous pyrolysis this latter case occurs in hydrothermal vent fields without a sedimentary cover emanating directly from oceanic ridges as for example on the east pacific rise at 13 n and 21 n and on the mid atlantic ridge at 26 n this process is probably also ubiquitous for all actively venting sediment starved oceanic ridges the hydrocarbon products generated in these areas have been compared in terms of composition organic matter sources and analogy to reservoir petroleum they represent a major carbon source for chemosynthetic assimilation by vent biota and are compositionally similar to normal petroleum

sedimentary organic matter preservation a test for selective degradation under oxic conditions the authors report here a test of the hypothesis that the extent of organic matter preservation in continental margin sediments is controlled by the average period accumulating particles reside in oxic porewater immediately beneath the water sediment interface oxygen penetration depths organic element compositions and mineral surface areas were determined for 16 sediment cores collected along an offshore transect across the washington continental shelf slope and adjacent cascadia basin individual amino acid sugar and pollen distributions were analyzed for a 11 to 12 cm horizon from each core and sup 14 c based sediment accumulation rates and stable carbon isotope compositions were determined from depth profiles within a subset of six cores from representative sites sediment accumulation rates decreased and dissolved o sub 2 penetration depths increased offshore along the sampling transect as a result oxygen exposure times oet increased seaward from decades mid shelf and upper slope to more than a thousand years outer cascadia basin organic contents and compositions were essentially constant within individual sediment cores but varied consistently with location in particular organic carbon surface area ratios decreased progressively offshore and with increasing oet three independent compositional parameters demonstrated that the remnant organic matter in farther offshore sediments is more degraded both concentrationmore and compositional patterns indicated that sedimentary organic matter exhibits a distinct and reproducible oxic effect oet helps integrate and explain organic matter preservation in accumulating continental margin sediments and hence provides a useful tool for assessing transfer of organic matter from the biosphere to the geosphere less

petrogenesis and u pb zircon chronology of felsic tuffs interbedded with turbidites eastern pontides orogenic belt ne turkey implications for mesozoic geodynamic evolution of the eastern mediterranean region and accumulation rates of turbidite sequences abstract the meso cenozoic geodynamic evolution of the eastern pontides orogenic belt which is one of the key areas of the alpine himalayan system is still controversial due to lack of systematic geological geophysical geochemical and chronological data the prevailing interpretation is that this belt represents the southern margin of eurasia during the mesozoic and its geodynamic evolution is related to northward subduction of oceanic lithosphere this paper reports the first detailed geological geochemical and chronological data from felsic tuffs interbedded with late cretaceous turbidites in the southern zone of the eastern pontides orogenic belt individual tuff layers are thin mostly 50 crystals the zircon u pb data show three statistically distinct ages at 84 81 and 77 ma with uncertainties of about 1 ma suggesting that tuff forming late cretaceous magmatism started about 84 ma ago and was episodically active over a minimum of 7 ma the age data also indicate that the average accumulation rate of the turbiditic sequence that hosts the felsic tuffs remained constant between 36 and 40 cm 10 ky their enrichment in lil and lre elements relative to hfs and hre elements and also strongly negative nb ta and ti anomalies are consistent with those of magmas generated by subduction related processes the tuffs have relatively low initial ratios of 143nd 144nd 0 512296 0 512484 end 2 1 and 7 2 and 87sr 86sr 0 704896 0 706159 their initial pb isotopic compositions range from 18 604 to 18 646 for 206pb 204pb from 15 644 to 15 654 for 207pb 206pb and from 38 712 to 38 763 for 208pb 204pb the distribution of sr nd isotopic compositions in the late cretaceous igneous rocks from different locations of the eastern pontides orogenic belt is consistent with two component mixing between depleted mantle and crust however the pb isotopic data are not compatible with two component mixing and require at least a third component considering all of the new data and also previous data such as southward migration and increasing potassium content of the late cretaceous arc volcanism the northward migration of cenozoic igneous activity northward drift of the belt since the late cretaceous and the existence of south dipping reverse fault systems in the whole region the meso cenozoic geodynamic evolution of the eastern pontides orogenic belt can be best explained by southward subduction of tethys oceanic lithosphere rather than northward subduction

late mesozoic stratigraphy in western liaoning china a review abstract based on progress in stratigraphic and paleontological studies we discuss the subdivision of late mesozoic strata in western liaoning focusing on the controversies surrounding the relationship of the jiufotang and shahai formations and whether or not the zhanglaogongtun and banlashan formations exist as distinct lithologic units we describe the late mesozoic strata at representative sections associated with the new discoveries we also discuss the correlation of late mesozoic strata between western liaoning and eastern heilongjiang and their implications for the ages of the strata in liaoning

late triassic tuff intervals in the ordos basin central china their depositional petrographic geochemical characteristics and regional implications abstract tuff intervals of upper triassic yanchang formation are laterally widespread in the ordos basin central china this paper focuses on magmatic origins and potential source regions of these tuff intervals through detail depositional petrographic and geochemical analyses most of the tuff intervals are well documented at the bottom of the chang7 oil reservoir unit and can be correlated laterally and certain tuff beds are reworked by turbidity current or seismic activity petrographic studies of the chang7 tuffs indicate that they are composed of crystal shards lithic shards and altered glass shards and the crystal shards include plagioclase quartz and biotite alteration of the chang7 tuffs is ubiquitous thus most of these tuffs transformed into illite smectite i s mixed layers which are identified by scanning electron microscopy sem and x ray diffraction xrd less common minerals are also detected in the chang7 tuffs such as zircon hematite siderite anatase major elements are determined by the x ray fluorescence xrf analysis the results indicate that the chang7 tuffs are enriched in k2o average 4 21 the ratio of sio2 al2o3 ranges from 1 73 to 2 85 average 2 17 and the ratio of tio2 al2o3 varies between 0 006 and 0 032 average 0 017 which imply that the chang7 tuffs originated from a felsic parental magma trace elements are determined by inductively coupled plasma mass spectrometry icp ms indicating the total rare earth element ree concentrations are variable and range from 117 46 to 466 83 ppm average 251 88 ppm ree distribution pattern of the chang7 tuffs presents a lree rightward incline with flat hree curve the value of eu ranges from 0 151 to 0 837 average 0 492 suggesting a strong to weak negative eu anomaly the chang7 tuffs show positive anomalies in rb th and u and negative anomalies in nb sr and eu on a primitive mantle normalized spidergram a preliminary analysis of the geochemical composition of the chang7 tuffs suggests a parental magma origin of rhyodacite dacite which came from volcanic arc related setting along an active continental margin combined with the chronology and geochemical studies of the synchronous tianshui rhyolite in the west qinling mountains we propose that the west qinling mountains is one of the potential source regions of these tuffs and the middle late triassic terminal closure of eastern tethys provided the arc related magma

enhancement of primary productivity in the western north pacific caused by the eruption of the miyake jima volcano 1 the eruption of the miyake jima volcano 34 08 n 139 53 e in the izu islands japan 180 km ssw of tokyo began on 8 july 2000 a substantial amount of nh3 gas was found to be emitted from the miyake jima volcano together with so2 gas and that geochemically significant quantities of aerosol particles composed of ammonium sulfate form in the plume through the use of satellite images the additional atmospheric deposition of ammonium sulfate caused an increase of phyto plankton in the nutrient deficient region south of the kuroshio the emission of volcanic gases from the miyake jima has likely been modifying the marine air quality as well as the open ocean ecosystem over parts of the western north pacific for the past several years

impact of seasonal variations in hydrological stresses and spatial variations in geologic conditions on a tce plume at an industrial complex in wonju korea spatial and temporal variations in a trichloroethylene tce plume at an industrial complex in wonju korea were examined based on hydrogeological data and seven rounds of groundwater quality data collected over a year the site has considerable vertical heterogeneities the top layer of soil is covered by impermeable paving material at several locations followed by a series of reclaimed or residual soil layers and with weathered rocks to the crystalline biotite granite at the bottom areal heterogeneity in the surface conditions plays an important role in controlling groundwater recharge the heterogeneity structure is influenced by complex surface conditions paved with asphalt and concrete owing to the presence of limited recharge area and concentrated summer precipitation events the effects of seasonal variations on groundwater hydraulics tend to diminish with distance from the recharge area this result was established by analysing the influence of the contrasting surface recharge conditions between the near source zone and the far zone and the seasonally concentrated precipitation on the transport patterns of a tce plume in addition variations in the plume s downstream contaminant flux levels were also analysed along a transect line near the source zone the results show that the general tendency of the tce plume contaminant concentration and mass discharges were reproducible if we account for seasonal recharge variations and the associated changes in the groundwater level during recharge events the tce concentration variations appear to be influenced by leaching of the residual dense non aqueous phase liquid dnapl tce trapped in the unsaturated zone this result shows that seasonal variations in contaminant plume near the source zone is inevitable at this site and that these variations indicate the presence of residual dnapl at or above the water table at least in some isolated locations copyright 2011 john wiley sons ltd

improving degradation of emerging organic compounds by applying chaotic advection in managed aquifer recharge in randomly heterogeneous porous media improving degradation rates of emerging organic compounds eocs in groundwater is still a challenge although their degradation is not fully understood it has been observed that some substances are preferably degraded under specific redox conditions the coupling of managed aquifer recharge with soil aquifer remediation treatment by placing a reactive layer containing organic matter at the bottom of the infiltration pond is a promising technology to improve the rate of degradation of eocs its success is based on assuming that recharged water and groundwater get well mixed which is not always true it has been demonstrated that mixing can be enhanced by inducing chaotic advection through extraction injection engineering in this work we analyze how chaotic advection might enhance the spreading of redox conditions with the final aim of improving degradation of a mix of benzotriazoles benzotriazole 5 methyl benzotriazole and 5 chloro benzotriazole the degradation of the first two compounds was fastest under aerobic conditions whereas the third compound was best degraded under denitrification conditions we developed a reactive transport model that describes how a recharged water rich in organic matter mixes with groundwater how this organic matter is oxidized by different electron acceptors and how the benzotriazoles are degraded attending for the redox state the model was tested in different scenarios of recharge both in homogenous and in heterogenous media it was found that chaotic flow increases the spreading of the plume of recharged water consequently different redox conditions coexist at a given time facilitating the degradation of eocs

weathering and global denudation a negative correlation between sediment yield and weathering history as measured by the chemical alteration cia of the suspended sediment is observed for many of the world s major rivers and other regions of denudation the weathering history is a first order control on the sediment yield of such areas termed equilibrium denudation regions for other areas data scatter with either apparent increases or decreases of sediment yield for given cia values these areas are termed nonequilibrium denudation regions low sediment yields can be attributed to moderated erosion either natural or human induced and or the incorporation of unweathered glacial debris accelerated erosion resulting in high sediment yield is primarily human induced and results from cultivation and other land use each of these effects has a profound influence on global sediment discharge from the continents pre human suspended sediment discharge from the continents is estimated to be 12 6 times 10 15 g yr or about 0 6 the

radiative forcing and climate impact resulting from so2 injections based on a 200 000 year record of plinian eruptions along the central american volcanic arc we present for the first time a self consistent methodology connecting volcanological field data to global climate model estimates for a regional time series of explosive volcanic events using the petrologic method we estimated so2 emissions from 36 detected plinian volcanic eruptions occurring at the central american volcanic arc cava during the past 200 000 years together with simple parametrized relationships collected from past studies we derive estimates of global maximum volcanic aerosol optical depth aod and radiative forcing rf describing the effect of each eruption on radiation reaching the earth s surface in parallel aod and rf time series for selected cava eruptions are simulated with the global aerosol model maecham5 ham which shows a relationship between stratospheric so2 injection and maximum global mean aod that is linear for smaller volcanic eruptions 5 mt so2 and nonlinear for larger ones 5 mt so2 and is qualitatively and quantitatively consistent with the relationship used in the simple parametrized approximation potential climate impacts of the selected cava eruptions are estimated using an earth system model of intermediate complexity by rf time series derived by 1 directly from the global aerosol model and 2 from the simple parametrized approximation assuming a 12 month exponential decay of global aod we find that while the maximum aod and rf values are consistent between the two methods their temporal evolutions are significantly different as a result simulated global maximum temperature anomalies and the duration of the temperature response depend on which rf time series is used varying between 2 and 3 k and 60 and 90 years for the largest eruption of the cava dataset comparing the recurrence time of eruptions based on the cava dataset with the duration of climate impacts based on the model results we conclude that cumulative impacts due to successive eruptions are unlikely the methodology and results presented here can be used to calculate approximate volcanic forcings and potential climate impacts from sulfur emissions sulfate aerosol or aod data for any eruption that injects sulfur into the tropical stratosphere

guidelines for evaluating petroleum source rock using programmed pyrolysis rock eval pyrolysis is used to rapidly evaluate the petroleum generative potential and thermal maturity of rocks accurate conclusions require programs every 30 60 ft 9 18 m understanding of interpretive pitfalls and supporting data such as visual kerogen vitrinite reflectance and elemental analyses the generative potential of coals is commonly overestimated by pyrolysis and is best determined by elemental analysis and organic petrography most coals show high s2 s3 5 and low hi values 300 mg hc g toc migrated oil and mud additives which alter rock eval data can sometimes be removed by special processing for immature rocks bimodal s2 peaks and pi values over 0 2 indicate contamination pyrolysis downgrades organic poor clay rich rocks which show lower hi and higher tmax values than isolated kerogen because of adsorption of pyrolyzate on the clays tmax values for small s2 peaks 0 2 mg hc g toc are unreliable tmax is affected by maturation organic matter type contamination and the mineral matrix s3 is sensitive to inorganic and adsorbed carbon dioxide and to instrumentation problems acidification of carbonate rich samples and proper maintenance improves s3 measurement constant sample weights 100 mg are recommended below a threshold weight tmax increases by up to 10 c and other parameters decrease organic rich samples which overload the detector can be diluted with carbonate detector linearity is determined by pyrolyzing various weights of an organic rich rock

deducing the distribution of terminal electron accepting processes in hydrologically diverse groundwater systems the distribution of microbially mediated terminal electron accepting processes teaps was investigated in four hydrologically diverse groundwater systems by considering patterns of electron acceptor nitrate sulfate consumption intermediate product hydrogen h sub 2 concentrations and final product ferrous ion sulfide and methane production in each hydrologic system a determination of predominant teaps could be arrived at but the level of confidence appropriate for each determination differed in a portion of the lacustrine aquifer of the san joaquin valley for example all three indicators sulfate concentrations decreasing h sub 2 concentrations in the 1 2 nmol range and sulfide concentrations increasing along flow paths identified sulfate reduction as the predominant teap leading to a high degree of confidence in the determination in portions of the floridan aquifer and a petroleum hydrocarbon contaminated aquifer sulfate reduction and methanogenesis are indicated by production of sulfide and methane and hydrogen concentrations in the 1 4 nmol and 5 14 nmol range respectively however because electron acceptor consumption could not be documented in these systems less confidence is warranted in the teap determination in the black creek aquifer no pattern of sulfate consumption and sulfide production were observed but h sub 2 concentrations indicated sulfate reduction as the predominant teap in this case more where just a single line of evidence is available the least confidence in the teap diagnosis is justified because this methodology is based on measurable water chemistry parameters and upon the physiology of microbial electron transfer processes it provides a better description of predominant redox processes in groundwater systems than more traditional eh based methods less

lithofacies and sequence stratigraphy of the barnett shale in east central fort worth basin texas ten barnett shale lithofacies have been recognized in a 223 ft 68 m long core from johnson county texas eight of these lithofacies match those previously identified in the main producing area of the newark east barnett shale field in the northern part of the fort worth basin but two new lithofacies have been identified in this core resedimented spiculitic mudstone lithofacies and lag deposits both of which are indicative of a relatively higher energy environment and downslope resedimentation of shallower water deposits the recognition of cyclical stacking patterns of the lithofacies condensed sections css and transgressive surfaces of erosion were the keys to establishing the sequence stratigraphic framework in these fine grained rocks which consists of seven stratigraphic intervals in the lower barnett shale and nine stratigraphic intervals in the upper barnett shale spectral gamma ray uranium and thorium logs aided in this objective and are recommended for future sequence stratigraphic studies of these and other shales the sequence stratigraphic framework reveals that the lower barnett shale in this area was deposited mainly in a low energy relatively deep water environment somewhat far from a terrigenous source area which probably lies to the northwest by contrast the upper barnett shale was deposited in an oxygenated shallower water environment which had a source area from the west and southwest sides of the basin the higher frequency of sea level fluctuation during development of the upper barnett shale most probably indicates periodic tectonic activity perhaps associated with a structural high that was susceptible to sea level fluctuations alternatively it could have resulted from the onset of glaciations in gondwanaland during this time this higher frequency may indicate that the upper barnett is chesterian in age because cyclicity was higher than during the osagean and meramecian stages if so there may be more high frequency cycles than recognized in this core siliceous sponge spicules are more common in this core than in more northerly cores so more brittle facies might prevail in the southern part of the fort worth basin high gamma ray log responses which are caused by a high total organic carbon and or in situ phosphate minerals are commonly found in css and can be used for regional correlations however high gamma ray phosphatic deposits that have been resedimented to downslope positions by sediment gravity flows are an exception to the previous statement correlation of the barnett stratigraphic intervals now provides a north to southeast stratigraphic framework along the fort worth basin relative hydrocarbon potential rhp is an organic geochemical parameter applied to this core and found to provide an indicator of marine transgressions and regressions we recommend continued testing and use of the rhp parameter for high frequency sequence stratigraphic analysis of unconventional gas shales

palaeoproductivity at the antarctic continental margin opal and barium records for the last 400 ka abstract records of biogenic opal and barium were measured in sediment cores at the antarctic continental margin in the area of the weddell lazarev and cosmonaut seas these records provide a qualitative and quantitative tool to estimate changes in palaeoproductivity over the last 400 ka the stratigraphy of the investigated cores is calibrated to a lithostratigraphy adjusted to a stable isotope record from the eastern weddell sea which is supported by a th dating method we present evidence that interglacial productivity along the antarctic continental margin is twice as high compared to subantarctic sites near south orkney a glacial interglacial pattern with high productivity during peak warm stages can be observed back to 400 ka high interglacial productivity is linked to a reduced sea ice coverage which is regulated by the heat flux introduced by north atlantic deep water nadw to the antarctic ocean generally good correlations between the barium and opal records of the sediment cores indicate that dissolution of opal in the water column and the sediment does not obscure the surface productivity signal therefore in this area biogenic opal in combination with other proxies can be used for palaeoproductivity estimates palaeoproductivity is also assessed quantitatively from the barium record using the approaches of dymond et al dymond j suess e lyle m 1992 barium in deep sea sediments a geochemical proxy for paleoproductivity paleoceanography 7 163 181 and francois et al francois r honjo s manganini s j ravizza g e 1995 biogenic barium fluxes to the deep sea implications for paleoproductivity reconstructions glob biochem cycles 9 2 289 303 palaeoproductivity rates obtained by both methods show a good temporal correspondence in peak warm stages higher values are computed with the approach of dymond et al 1992 though some barium may be provided by lateral advection of material as indicated by th data near south orkney both methods provide values which are representative of a high productivity area they are drastically reduced during glacial times the extent and duration of sea ice coverage and the persistence of coastal polynyas is considered to be of primary importance in controlling the flux of biogenic material to sediments of the antarctic continental margin

inorganic geochemical indicators of glacial interglacial changes in productivity and anoxia on the california continental margin abstract evidence from sediments in cores collected from within the present oxygen minimum zone omz 600 1200 m on the central and northern california margins record several episodes during the last interstadial ois 3 ca 60 24 ka of deposition of laminated sediments containing elevated concentrations of several trace elements indicative of anoxic conditions e g mo ni zn and cu the presence of abundant well preserved organic matter as well as lack of bioturbation and the presence of elevated concentrations of mo and other trace elements all support the theory that the omz in the northeastern pacific ocean was more intense possibly anoxic at several times during the late pleistocene sediments of all ages in cores from the southern california margin contain elevated concentrations of mo suggesting that this area has always had higher rates of sulfate reduction than either the central or northern california areas most of the ba in sediments in all cores collected on the upper continental slope 200 2700 m off california and southern oregon is derived from detrital clastic material and this source did not change much in time however the amount of biogenic ba did vary with time and these variations closely follow the temporal variations in organic c corg mass accumulation rate using ba and corg mass accumulation rates as proxy variables for productivity all cores show that organic productivity under the california current upwelling system was highest during ois 3 and the holocene and lowest during the last glacial interval lgi ca 24 10 ka all paleoproductivity proxy variables indicate that the southern california area has always experienced higher productivity than other areas under the california current at least over the last 50 ky

high resolution geochemical analysis of organic matter accumulation in the qingshankou formation upper cretaceous songliao basin ne china abstract in the well known continental songliao basin the oil shale successions of the cretaceous qingshankou formation are excellent source rocks for oil the oil shale layers with high toc total organic carbon contents developed at the bottom of the formation they are divided into the lower oil shale toc up to 18 3 and the upper oil shale layer toc up to 14 4 the oil shale layers and accompanying mudstones are investigated by high resolution analyses of drill cores by pyrolysis organic petrology organic and inorganic geochemistry the results demonstrate the predominance of type i kerogen derived from algal microbial mats i e lamalginite however increased proportions of plant derived organic matter are indicated by rock eval parameters and the presence of vitrinite in the upper oil shale as evidenced from lower concentrations of hopanes higher sinking rates of organic matter om are suggested to have been responsible for a lower extent of microbial degradation during accumulation of the lower oil shale unit the environmental conditions are characterized by anoxic saline bottom water overlain by an extended zone of freshwater favorable for om production and preservation under these preconditions oil shale thickness and quality are governed by primary productivity related to accommodation space and nutrient supply redox conditions within the water column are the key factor controlling organic matter preservation

tracing of residual multiple dnapl sources in the subsurface using 222rn as a natural tracer at an industrial complex in wonju korea depth discrete tracing of residual dense non aqueous phase liquid dnapl sources in the subsurface is of great importance in making decisions related to contaminated groundwater remediation temporal variations in the natural tracer 222rn and contaminant concentrations in groundwater contaminated with multiple chlorinated contaminants such as trichloroethene carbon tetrachloride and chloroform were examined to trace residual multiple dnapl contaminants at an industrial complex in wonju korea the 222rn activities and multiple dnapl concentrations in the groundwater fluctuated irregularly according to the groundwater recharge the natural tracer 222rn in groundwater present in the soil layer originating from the underlying crystalline biotite granite had a wide range from 29 000 to 179 000 bq m3 and total concentrations of chlorinated solvents ranged from 0 06 to 17 77 mg l indicating the ambiguous results of 222rn for tracing the residual dnapl sources in this paper a method is presented to locate zones with a high probability of containing depth discrete residual multiple dnapl sources using 222rn and considering relative contaminant concentrations the results demonstrate that the combination of the 222rn activities as a natural tracer and the relative contaminant concentrations is able to be used as a useful tool for tracing residual dnapls

relationship of pyroclastic volcanism and lake water acidification to jehol biota mass mortality events early cretaceous northeastern china abstract geochemical analysis of the 14 4 m thick lacustrine succession of the lower cretaceous yixian formation jehol group has yielded new insights concerning vertebrate mass mortality events in the lake sihetun volcanic caldera in western liaoning province northeastern china that produced the jehol biota fossil lagerstatten the long term evolution of the caldera system resulted in a shift from felsic to mafic magma chemistry accompanied by a reduced frequency of pyroclastic eruptions declining hydrothermal activity and lower lacustrine productivity the basal tetrapod beds exhibit strong hydrothermal influence as indicated by enrichments of boron b certain alkalis rb cs rare earth elements rees yttrium y and many metals e g co cr cu ge mo ni sb u v and w and by strongly negative molybdenum isotope compositions 98mo to 2 50 that may record large fractionations between molybdate and thiomolybdate species in the sihetun caldera hydrothermal system in contrast the overlying fish beds and non fossiliferous beds have an elemental and mo isotopic composition similar to calc alkaline basalts 98mo 0 29 0 04 in the surrounding watershed suggesting weathering of yixian formation volcanic rocks as the major source of sediment during its

subduction zone volcanic ash can fertilize the surface ocean and stimulate phytoplankton growth evidence from biogeochemical experiments and satellite data volcanoes confront earth scientists with new fundamental questions can airborne volcanic ash release nutrients on contact with seawater thereby excite the marine primary productivity mpp and most notably can volcanoes through oceanic fertilization affect the global climate in a way that is so far poorly understood here we present results from biogeochemical experiments showing that 1 volcanic ash from subduction zone volcanoes rapidly release an array of nutrients co limiting algal growth in vast oceanic areas 2 at a speed much faster minute scale than hitherto known and that marine phytoplankton from low iron oceanic areas can swiftly within days utilize iron from volcanic sources we further present satellite data possibly indicating an increase of the mpp due to the seaward deposition of volcanic particulate matter our study supports the hypothesis that oceanic iron fertilization with volcanic ash may play a vital role for the development of the global climate

tectonic and climate control of oil shale deposition in the upper cretaceous qingshankou formation songliao basin ne china oil shales were deposited in the songliao basin ne china during the upper cretaceous period representing excellent hydrocarbon source rocks high organic matter om contents a predominance of type i kerogen and a low maturity of om in the oil shales are indicated by bulk geochemical parameters and biomarker data a major contribution of aquatic organisms and minor inputs from terrigenous land plants to om input are indicated by n alkane distribution patterns composition of steroids and organic macerals strongly reducing bottom water conditions during the deposition of the oil shale sequences are indicated by low pristane phytane ratios high c14 aryl isoprenoid contents homohopane distribution patterns and high v ni ratios enhanced salinity stratification with mesosaline and alkaline bottom waters during deposition of the oil shales are indicated by high gammacerane index values low mttc ratios high carotene contents low toc s ratios and high sr ba ratios the stratified water column with anoxic conditions in the bottom water enhanced preservation of om moderate input of detrital minerals during the deposition of the oil shale sequences is reflected by titanium concentrations in this study environmental conditions in the paleo lake leading to om accumulation in the sediments are related to sequence stratigraphy governed by climate and tectonics the first member of the qingshankou formation k2qn1 in the songliao basin containing the oil shale sequence encompasses a third order sequence that can be divided into three system tracts transgressive system tract tst highstand system tract hst and regressive system tract rst enrichment of om changed from low values during tst i to high moderate values during tst ii iii and hst i ii low om enrichment occurs during rst i and rst ii therefore the highest enrichment of om in the sediments is related to stages of mid late tst and early hst

sedimentary basin evolution gravity flows volcanism and their impacts on the formation of the lower cretaceous oil shales in the chaoyang basin northeastern china abstract no detailed research has been carried out on the oil shales that are interbedded with gravity flow deposits and volcaniclastic rocks in the third member of the jiufotang formation in order to study the impact of basin evolution gravity flows and volcanism on oil shale formation petrology sedimentology sequence stratigraphy organic geochemistry and elemental geochemistry were used to characterise the oil shales extensional tectonic subsidence is suggested as the controlling factor for basin evolution the predominant maceral in the oil shales is sapropelinite suggesting organic matter was derived from mainly aquatic organism especially algae element indices u cu mo zn sr ba th g g zr g g and the chemical index of alteration cia show that the water conditions during deposition of the oil shales were anoxic and brackish with little terrigenous detrital input and a cold and dry palaeoclimate gravity flows were accompanied by the input of terrestrial detritus and a degree of oxygenation of the bottom waters reducing oil shale formation volcanic eruptions ejected intermediate acidic ashes not only leading to climate cooling but also either enhancing algal blooms by a fertilisation effect due to minor volcanic ash input or inhibiting algal blooms by a poisoning effect due to major volcanic ash input there is synchronicity between the occurrence of rifting gravity flows volcanism and earthquakes the best periods for oil shale formation were during intermissions between tectonic movement when there were few gravity flows volcanic eruptions or earthquakes high bioproductivity and lake expansion along with an anoxic environment were the main controlling factors for high quality oil shale formation there is a series of oil shale bearing rift basins formed in northeastern china that share a similar geological setting so this research provides a useful example for future resource exploration of coeval oil shales in northeastern china

evolution of a middle jurassic back arc basin cedros island baja california evidence from a marine volcaniclastic apron a rifted arc ophiolite assemblage and over lying volcaniclastic rocks all of late middle jurassic age represent a fragment of the frontal arc margin of a back arc basin now exposed on cedros island in baja california mexico ophiolite generation was immediately followed by progradation of a deep marine volcaniclastic apron gran cannon formation contemporaneous with the growth of island arc volcanoes this back arc apron shows relatively simple uniform sedimentation patterns that may be recognizable in other back arc basins isolated from terrigenous sediment influx the progradational back arc apron sequence includes from base to top 1 the tuff lithofacies thin bedded well sorted laterally continuous tuffs that thicken into basement paleo lows these were deposited from dilute sediment gravity flows generated by eruptions from a deeply submerged nascent arc 2 the lapilli tuff tuff breccia lithofacies medium to very thick bedded lapilli tuffs and tuff breccias these were deposited from debris flows on proximal parts of the apron and high density turbidites were deposited on more distal parts this lithofacies records increasing generation and resedimentation of scoriaceous and hyaloclastic debris as the summits of the arc volcanoes grew nearer to sea level 3 the primary volcanic lithofacies monolithologic dacite pyroclastic flows were produced during the eruption of differentiated magmas which climaxed the growth of the island arc basalt lava flows were fed from fissures that extended down the apron within the back arc basin pyroclastic rocks of the back arc apron were blanketed with silty basinal turbidites epiclastic facies that record abrupt cessation of volcanism and erosion of the arc within about 10 m y of ophiolite generation reflecting the temporal episodicity of back arc basins it is predicted from this study that the frontal arc side of back arc spreading centers is preferentially preserved in the geologic record relative to the center of the basin it is suggested that the hot frontal arc side of the basin is prone to intra plate volcanism but is unaffected by faulting subsequent to basin initiation several factors lead to slumps occurring more frequently on the arc flank of back arc basins than in any other tectonic setting except perhaps intra arc marine basins

origin alteration and geochemical correlation of late permian airfall tuffs in coal measures sydney basin australia abstract the late permian illawarra coal measures of the southern sydney basin contain tuffs derived from altered pyroclastic airfall material these units represent ideal stratigraphic time planes because as the products of airfall volcanic ashes they are distributed over wide areas in short periods of geological time geochemical correlation of the tuffs of the illawarra coal measures with similar units in the stratigraphically equivalent newcastle coal measures offers a unique opportunity to understand the temporal and spatial relations during deposition of coal bearing units in the sydney basin thirty five core samples comprising 12 samples from each of the burragorang and farmborough claystone members and 11 samples from the huntley claystone member were analysed for major and trace elements by x ray fluorescence and instrumental neutron activation and the results were subjected to stepwise discriminant analysis the elements that served as the best discriminators between tuffs were in order of atomic number ti v sn hf and th samples for basin wide correlation were taken from thick interseam tuffs of the newcastle coal measures and treated as unknowns in the discriminant model the burragorang claystone member shows a strong geochemical correlation with the awaba tuff and the farmborough claystone member correlates with the warners bay tuff the huntley claystone member however has proved difficult to correlate with the nobby s tuff the proposed stratigraphic equivalent in the newcastle coal measures petrographic data for tuffs of the illawarra coal measures indicate that they were deposited by airfall mechanisms and consist mainly of kaolinite and mixed layer illite smectite clays quartz and plagioclase crystal fragments lithic fragments and secondary calcite and siderite zr tio2 and nb y ratios tectonic discrimination diagrams and chondrite normalised ree patterns la yb 3 3 to 11 9 are identical to those for tuffs of the newcastle coal measures and are interpreted as being derived from magma that was calc alkaline rhyodacitic to rhyolitic in composition and derived from a continental volcanic arc tectonic setting the source of the tuffs is interpreted to be an active volcanic arc to the east of the present coastline currarong orogen but a lack of evidence from below the continental shelf makes it difficult to make concrete conclusions on its likely extent and composition

warm humid paleoclimate control of salinized lacustrine organic rich shale deposition in the oligocene hetaoyuan formation of the biyang depression east china abstract lacustrine organic rich shales are widely developed within the oligocene biyang depression in the nanxiang basin in east china and across southeast asia these shales have been proven as hydrocarbon source rocks of crude oil as well as sources and reservoirs of shale oil understanding the deposition of these shales is essential to reconstruct the paleoenvironment and paleoclimate during the oligocene in east china as well as target the potential shale oil resources based on x ray diffraction organic and inorganic petrologic organic and inorganic geochemical and stable isotopic analyses paleoenvironment paleoclimate and hydrocarbon potential of the lacustrine organic rich shales in the oligocene hetaoyuan formation were investigated the mineral composition of hetaoyuan formation organic rich shales is dominated by clay minerals followed by quartz plagioclase calcite dolomite pyrite and gypsum six lithotypes are identified including siltstone silty shale clay shale calcareous shale dolomite shale and massive mudstone the organic matter om of the organic rich shales is dominated by type i kerogen lamalginite maturity parameters tmax biomarker ratios and calculated vitrinite reflectance suggest that the om enters the oil window maturity high toc and generative potential together with high contents of brittle minerals including quartz plagioclase and carbonates reveal the oligocene hetaoyuan formation hold good to very good potential of shale oil exploitation six organic rich shale layers have been identified in the hetaoyuan formation shale layer 1 to 6 from top to bottom among them shale layers 5 and 3 hold the best shale oil potential and therefore be investigated in the present paper shale layer 5 was deposited in a semi deep lacustrine environment under the moderately warm humid paleoclimate further dividing into lower middle and upper units relatively low toc contents av 2 6 wt in the lower unit are probably caused by high sedimentation rate high bioproductivity under favorable preservation conditions led to relatively high toc contents av 3 6 wt in the middle unit less reducing conditions together with moderate low bioproductivity resulted in relatively low toc contents av 2 6 wt in the upper unit warm humid paleoclimate prevailed during deposition of shale layer 3 deepened water depth and formed a deep lacustrine environment the stratified water column led to stable anoxic condition and photic zone euxinia in the saline deep lacustrine environment which enabled the accumulation of high amounts of om av 4 9 wt toc under excellent preservation av hi 710 mg hc g toc the results of core scanning analysis indicate that formation of the laminated shales probably controlled by seasonal fluctuations of paleoclimate

depositional environment of oil shale within the eocene jijuntun formation in the fushun basin ne china abstract the non marine fushun basin in ne china is a fault controlled basin filled with eocene sediments it hosts the largest opencast coal and oil shale mine in asia a single thick oil shale layer overlying sub bituminous coal occurs within the middle eocene jijuntun formation based on mineralogy inorganic and organic geochemistry organic petrography stable isotope geochemistry and vitrinite reflectance measurements the depositional environment and the oil shale potential of the oil shale bearing succession were investigated the jijuntun formation is subdivided into a lower and an upper unit characterized by a low and high quality oil shale respectively the thick oil shale layer of the jijuntun formation developed under long lasting stable conditions in a deep freshwater lake after drowning of a swamp the organic matter in the lower unit is characterized by landplant derived macerals the sediments containing a type ii kerogen hi 400 mghc gtoc were deposited during warm and humid conditions lacustrine organisms predominant in the upper unit are forming kerogen type i hi 700 mghc gtoc high bioproductivity and excellent preservation conditions resulted in high toc contents up to 23 6 wt in the upper unit the organic matter preservation was controlled by photic zone anoxia originating in a temperature stratified water column in the deep lake without significant changes in bottom water salinity mid eocene cooling during deposition of the upper unit of the jijuntun formation is reflected by clay mineral composition a hot and arid climate favoring brackish conditions in a shallow lake prevailed during accumulation of the overlying carbonate rich xilutian formation individual geochemical parameters in the fushun basin have to be used with caution e g the maturity proxy tmax is affected by kerogen type the redox proxy pr ph ratio is probably biased by different sources of isoprenoids this demonstrates the importance of multi proxy studies

chemical weathering since the little ice age recorded in lake sediments a high resolution proxy of past climate because of the different geochemical behaviour of rubidium and strontium in earth surface processes variations of the rb sr ratios in lake sediments were used as a geochemical proxy of chemical weathering and past climate in a single watershed low magnetic susceptibility low caco3 low sr concentration and hence high rb sr ratio in the lake sediments indicate weak chemical weathering under a cold but wet climate during the little ice age lia in the closed daihai lake watershed the concordant change in both sr and caco3 concentrations with 18o values in the dunde ice core suggests that weak chemical weathering during the wet lia was controlled by air temperature after the lia however precipitation played a dominant role in chemical weathering copyright 2001 john wiley sons ltd

sedimentation rate dilution preservation and total organic carbon some results of a modelling study abstract a modelling exercise was undertaken to evaluate the positive preservational and negative diluent effects of sedimentation rate sr on the total organic carbon toc content of marine sediments and to use multiple regression analysis of modern data to predict toc data presented show the predicted marine toc using the carbon burial efficiency be versus sr relationship of betts and holland betts j n holland h d 1991 the oxygen content of ocean bottom waters the burial efficiency of organic carbon and the regulation of atmospheric oxygen palaeogeography palaeoclimatology palaeoecology global and planetary change section 97 5 18 calculated for a range of sr water depths primary productivities and four fixed be values the results suggest that the preservation effect of sr only enhances toc at 5 cm ka in oxic regimes after which dilution occurs if carbon supply is held constant above 35 cm ka there is no appreciable difference in toc regardless of whether the sea floor is anoxic or not below 10 cm ka there is a strong divergence in oxic and anoxic toc values observed positive correlations of sr and toc at 5 cm ka are largely an artefact of including sites from shallower depths and or higher productivities multiple regression analysis mra of modern marine sediment data suggests that once re scaled to allow for their non linear effect dissolved oxygen values may be a significant additional variable in determining the toc predicting an approximately 2 5 4 0 times higher toc in anoxic facies compared with fully oxic ones 4 ml l dissolved oxygen all other things being equal the mra also indicates a generally negative partial correlation between carbon delivery flux and be in modern sediments producing a significant moderating effect on the predicted toc

diffusion of landfill leachate through compacted natural clays containing small amounts of carbonates and sulfates abstract diffusion of a synthetic urban landfill leachate through compacted natural illitic clays and the role of reactive accessory minerals carbonates and gypsum in the geochemical behavior of major soluble ions are evaluated the leachate is composed of nh 4 and na 0 25 m balanced by cl 0 25 m acetate 0 1 m and hco 3 0 15 m the ph is 7 8 and it is typical of the mature stage of organic matter degradation within an urban landfill laboratory scale diffusion tests were performed over 4 months long term experiment lt and 2 weeks short term experiment st the st experiments were designed to allow the measurement of the cl gradient as a diffusion tracer in the compacted clay in the lt experiments the chemical gradients were already at steady state but geochemical reactions involving dissolution of gypsum and precipitation of calcite were observed evolution of pore water chemistry mineralogy cation exchange properties and the specific surface of clays were determined numerical simulations were carried out using the geochemical code retraso chloride transport precipitation of carbonates ph buffering and ca2 nh 4 cation exchange reactions took place in the laboratory tests apparent cl diffusion coefficients were determined by direct modeling of the st tests and validated with the lt experiments these coefficients were considered in the simulation of transport coupled with experimentally calculated exchange constants and dissolution precipitation reactions of gypsum and carbonates sulfate reduction coupled with acetate oxidation has been proven to be relevant in the sample with significant concentration of so 4 2 bailen this process also includes significant precipitation of carbonates mainly calcite and causes a decrease of so 4 2 in the porewater

geochemical and tight reservoir characteristics of sedimentary organic matter bearing tuff from the permian tiaohu formation in the santanghu basin northwest china abstract tuff reservoirs have been found in petroliferous basins but have not been sufficiently studied the discovery of the permian tiaohu formation reservoir in the santanghu basin in northwest china has offered an excellent opportunity to further enhance our knowledge of the tuff s geochemical and reservoir characteristics the tuff reservoir has the peculiar property of being a sedimentary organic matter bearing tuff in this study an integrated analysis of the organic geochemistry elemental and mineral compositions quartz crystallinity pore types and tight reservoir characteristics was conducted based on samples from the 20 30 m thick tuffs the extracted tuff samples have total organic carbon toc values of 0 5 1 0 wt total hydrocarbon yield values of 2 6 mg g and hydrogen index values of 20 336 mg hc g toc the organic matter consists predominantly of type iii and ii 2 kerogens and the temperature of the maximum yield of pyrolysate varies from 420 to 450 c which reflects the oil generating capacity of the rock the physical properties of the tuff are characterised by high porosity varying from 10 to 25 and low permeability the air permeability mainly ranges from 0 01 to 0 50 md the devitrification of vitreous textures within the tuff primarily dictates the reservoir s characteristics i e the greater the degree of devitrification the higher the porosity of the reservoir vitric tuffs have reservoirs with higher porosity than crystal vitric tuffs and the degree of devitrification is generally controlled by the burial depth temperature and organic matter organic acid content vitric tuffs with high porosity and permeability are usually located far from the crater and within the central lower part of the reservoir this research may influence geologists to pay more attention to the exploration value of this special type of reservoir in other regions

climatic control on the composition of carboniferous permian gondwana sediments khalaspir basin bangladesh abstract late paleozoic or permo carboniferous gondwana successions world wide are marked by widespread and lengthy glaciation 67 ma and multiple transitions from icehouse to greenhouse state mineralogical and compositional changes in sandstones and mudstones of the gondwana succession in drill hole gdh 45 from the khalaspir basin of bangladesh are interpreted in a climatic framework using the proxies of the mineralogical index of alteration mia and the chemical index of alteration cia low mia

sedimentary organic matter in condensed sections from distal oxic environments examples from the mesozoic of se france a detailed analysis of sedimentary organic matter or palynofacies was carried out on thermally immature to early mature upper jurassic and hauterivian condensed intervals in deep sea carbonate marl alternations outcropping in the vocontian basin se france all the condensed sections studied are characterized by intense bioturbation and very low organic carbon content 0 25 wt indicative of oxic depositional conditions oxic condensed sections display variable palynofacies signatures which are best illustrated by 1 the ratio of continental to marine constituents 2 the ratio of opaque to translucent phytoclasts i e woody debris and 3 the preservation of palynomorphs based on fluorescence intensity and morphological preservation state in transmitted light microscopy both of the ratios increase with the degree of palynomorph degradation which shows that phytoclasts especially the opaque ones become relatively concentrated in the most degraded facies these observations lead to the classification of oxic condensed sections into three organic facies types showing different degrees of preservation and palynofacies signatures type 1 organic facies display intense degradation and are characterized by high values of the ratio of continental to marine fraction they record unfavourable depositional environments for preservation of organic matter type 2 organic facies are most common and are characterized by a decreasing value of the ratio of continental to marine fraction type 3 organic facies display the same trend of the ratio of continental to marine fraction as type 2 but the palynomorph assemblage is better preserved type 1 and type 3 organic facies are relatively rare recognizing these organic facies types is important when analysing the relationship between sedimentary organic matter and sequence stratigraphy because it allows the use of the appropriate palynofacies parameters in particular the use of the ratio of continental to marine constituents usually a very good indicator of regressive transgressive trends becomes questionable in highly degraded intervals moreover distinguishing between well preserved or highly degraded palynofacies in condensed intervals provides valuable information on the oxicity of the depositional environment

sedimentary record and tectonic implications of mesozoic rifting in southeast mongolia the east gobi basin of mongolia is a poorly described late jurassic early cretaceous extensional province that holds great importance for reconstructions of mesozoic tectonics and paleogeography of eastern asia extension is especially well recorded in the structure and stratigraphy of the unegt and zuunbayan subbasins southwest of saynshand mongolia where outcrop and subsurface relationships permit recognition of prerift synrift and postrift mesozoic stratigraphic megasequences within the synrift megasequence three sequences developed in response to climatic and rift related structural controls on sedimentation where best exposed along the northern margin of the unegt subbasin each of the synrift sequences is bounded by unconformities and generally fines upward from basal alluvial and fluvial conglomerate to fluvial and lacustrine sandstone and mudstone resedimented ashes and basalt flows punctuate the synrift megasequence rifting began in the unegt subbasin prior to 155 ma with coarse alluvial filling of local fault depressions subsidence generally outstripped sediment supply and fresh to saline lacustrine environments expanding southward with time dominated the unegt zuunbayan landscape for much of latest jurassic early cretaceous time episodic faulting and volcanism characterized the basin system for the balance of the early cretaceous a brief period of compressional and or transpressional basin inversion occurred at the end of the early cretaceous prior to deposition of a widespread upper cretaceous overlap sequence the driver s of late jurassic early cretaceous extension remain uncertain because southeast mongolia occupied an intraplate position by the beginning of the cretaceous extension in the east gobi basin was coeval with collapse and extension of early mesozoic contractional orogenic belts along the northern and southern borders of mongolia and probably was a linked phenomenon strike slip faulting associated with collisions on the southern asian and mongol okhotsk margins likely also played a role in late mesozoic deformation of the east gobi region perhaps partitioning the gobi from apparently coeval large magnitude contractional deformation in the yinshan yanshan orogenic belt south of the study area in inner mongolia

barium accumulation in the atlantic sector of the southern ocean results from 190 000 year records extensive investigations of sedimentary barium were performed in the southern south atlantic in order to assess the reliability of the barium signal in antarctic sediments as a proxy for paleoproductivity maximum accumulation rates of excess barium were calculated for the antarctic zone south of the polar front where silica accumulates at high rates the correspondence between barium and opal supports the applicability of barium as a proxy for productivity within the antarctic zone north of today s average sea ice maximum interglacial vertical rain rates of excess barium are high with a maximum occurring during the last deglaciation and early holocene and during oxygen isotope chronozone 5 5 during these periods the maximum silica accumulation was supposedly located south of the polar front glacial paleoproductivity instead was low within the antarctic zone north of the polar front significantly higher barium accumulation occurs during glacial times the vertical rain rates however are as high as in the glacial antarctic zone therefore there was no evidence for an increased productivity in the glacial southern ocean

a kinetic approach for simulating redox controlled fringe and core biodegradation processes in groundwater model development and application to a landfill site in piedmont italy a three dimensional model for predicting redox controlled multi species reactive transport processes in groundwater systems is presented the model equations were fully integrated within a modflow family reactive transport code rt3d the model can simulate organic compound biodegradation coupled to different terminal electron acceptor processes a computational approach which uses the spatial and temporal distribution of the rates of different redox reactions is proposed to map redox zones the method allows one to quantify and visualize the biological degradation reactions occurring in three distinct patterns involving fringe pseudo core and core processes the capabilities of the numerical model are demonstrated using two hypothetical examples a batch problem and a simplified two dimensional reactive transport problem the model is then applied to an unconfined aquifer underlying a leaking landfill located near the city of turin in piedmont italy at this site high organic load from the landfill leachate activates different biogeochemical processes including aerobic degradation denitrification manganese reduction iron reduction sulfate reduction and methanogenesis the model was able to describe and quantify these complex biogeochemical processes the proposed model offers a rational framework for simulating coupled reactive transport processes occurring beneath a landfill site

earthquake classification location and error analysis in a volcanic environment implications for the magmatic system of the 1989 1990 eruptions at redoubt volcano alaska abstract determination of the precise locations of seismic events associated with the 1989 1990 eruptions of redoubt volcano posed a number of problems including poorly known crustal velocities a sparse station distribution and an abundance of events with emergent phase onsets in addition the high relief of the volcano could not be incorporated into the hypoellipse earthquake location algorithm this algorithm was modified to allow hypocenters to be located above the elevation of the seismic stations the velocity model was calibrated on the basis of a posteruptive seismic survey in which four chemical explosions were recorded by eight stations of the permanent network supplemented with 20 temporary seismographs deployed on and around the volcanic edifice the model consists of a stack of homogeneous horizontal layers setting the top of the model at the summit allows events to be located anywhere within the volcanic edifice detailed analysis of hypocentral errors shows that the long period lp events constituting the vigorous 23 hour swarm that preceded the initial eruption on december 14 could have originated from a point 1 4 km below the crater floor a similar analysis of lp events in the swarm preceding the major eruption on january 2 shows they also could have originated from a point the location of which is shifted 0 8 km northwest and 0 7 km deeper than the source of the initial swarm we suggest this shift in lp activity reflects a northward jump in the pathway for magmatic gases caused by the sealing of the initial pathway by magma extrusion during the last half of december volcano tectonic vt earthquakes did not occur until after the initial 23 hour long swarm they began slowly just below the lp source and their rate of occurrence increased after the eruption of 01 52 ast on december 15 when they shifted to depths of 6 to 10 km after january 2 the vt activity migrated gradually northward this migration suggests northward propagating withdrawal of magma from a plexus of dikes and or sills located in the 6 to 10 km depth range precise relocations of selected events prior to january 2 clearly resolve a narrow steeply dipping pencil shaped concentration of activity in the depth range of 1 7 km which illuminates the conduit along which magma was transported to the surface a third event type named hybrid which blends the characteristics of both vt and lp events originates just below the lp source and may reflect brittle failure along a zone intersecting a fluid filled crack the distribution of hybrid events is elongated 0 2 0 4 km in an east west direction this distribution may offer constraints on the orientation and size of the fluid filled crack inferred to be the source of the lp events

climate driven paleolimnological change controls lacustrine mudstone depositional process and organic matter accumulation constraints from lithofacies and geochemical studies in the zhanhua depression eastern china abstract the influence of paleoclimate on the depositional process of lacustrine mudstone and organic matter accumulation is important to both paleoclimate reconstruction and hydrocarbon exploration here we study the lower third member es3l of the eocene shahejie formation in the zhanhua depression bohai bay basin eastern china in order to understand how paleoclimate influenced depositional processes and organic matter accumulation of lacustrine organic rich mudstone by combining detailed core descriptions and microscopic observations and high resolution mineralogical and geochemical analyses we identified two major lithofacies including massive calcareous mudstone and laminated calcareous mudstone from the luo 69 drilling core the sedimentologic observations and changes of geochemical proxies including detritus index ln al2o3 na2o b ga and v v ni suggest that the massive calcareous mudstone was deposited in a small shallow salt lake that was dysoxic anoxic and the paleoclimate in the lake catchment was cool and arid and the laminated calcareous mudstone was deposited in a large and deep stratified lake which has anoxic highly saline bottom and oxic less saline surface water and the lake catchment was more humid and warm the dominant lithofacies changed from laminated calcareous mudstone to massive calcareous mudstone in the studied core suggesting that the lake became shallower and smaller when the paleoclimate became cooler and drier through time such a climate trend may be a response to global cooling during the middle eocene the average total organic content toc in both lacustrine highstand and lowstand are comparable even though the lake water chemistry and amount of terrigenous input are different we infer that the accumulation of organic matter within the lacustrine highstand was controlled by the combination of primary productivity carbonate production and preservation in anoxic bottom water while accumulation within lacustrine lowstand was only controlled by primary productivity

basin evolution and oil shale deposition during upper cretaceous in the songliao basin ne china implications from sequence stratigraphy and geochemistry abstract the controlling factors of oil shale formation within the upper cretaceous qingshankou and nenjiang formations of the songliao basin are investigated by petrological and geochemical methods sediment deposition was balanced by basin subsidence resulting in the accumulation of cretaceous strata of high thickness global sea level fluctuations have been related to periods of oil shale deposition within the basin the results indicate a comparable depositional environment during oil shale formation within the two upper cretaceous strata with respect to palaeotectonic and palaeoclimate but differences in the accommodation space during accumulation of the two formations the larger accommodation space during deposition of the nenjiang formation resulted in the higher thickness and wider distribution of the oil shale members total thickness 11 2 32 m distribution area 4 48 103 km2 within the basin as compared to the oil shale of the qingshankou formation total thickness 2 19 3 m distribution area 1 3 103 km2 further differences exist with regard to the palaeoenvironment of oil shale formation and primary productivity deposition of the qingshankou formation 1st member and nenjiang formation 1st member took place within a saline brackish lake under anoxic conditions in the bottom water preservation of organic matter is suggested to have been less favorable during deposition of the nenjiang formation 2nd member higher primary productivity is believed to be the responsible factor for the accumulation of organic rich sediments in the qingshankou formation 1st member the interplay of these two factors i e preservation productivity leads to the formation of oil shale in the qingshankou formation average toc 8 32 tocmax 13 52 average oil yield 5 57 with better hydrocarbon source rock potential and slightly higher oil yield during pyrolysis as in the nenjiang formation average toc 7 76 tocmax 9 7 average oil yield 5 54 primary productivity is suggested as the main controlling factor on differences in oil shale quality and source rock potential between the two formations whereas the variations in quality within each formation mainly depend on the preservation of organic matter the high thickness wide spatial distribution and excellent hydrocarbon potential of the upper cretaceous oil shales in the songliao basin are suggested to have been the result of large accommodation space stable palaeoenvironmental conditions and high primary productivity

controls on iron mobilisation from volcanic ash at low ph insights from dissolution experiments and mossbauer spectroscopy the deposition of volcanic ash from explosive eruptions to the surface ocean is a source of iron fe for marine phytoplankton however the factors that determine the soluble and thus potentially bioavailable fraction of fe in ash from magma source to ocean sink remain poorly understood we investigate for the first time the release of both fe ii and fe iii from six natural ash samples in ph 1 h2so4 representative of exposure to aqueous low ph conditions during airborne transport mossbauer spectroscopy analysis of the ash suggests that the overall 168 h trends in fetot and fe ii fetot release by individual samples are governed by dissolution of fe bearing aluminosilicates or oxides of the ash bulk in contrast the initial 6 h trends in fe release may reflect chemical properties of the ash surface imparted by the ash s eruptive history supported in part by x ray photoelectron spectroscopy analysis preferential release of fe iii relative to fe ii immediately on ash input to acid is attributed to oxidation of ash surfaces within the eruption plume additionally prior exposure of ash to a hf or hcl rich plume may enhance fe release by respectively reducing aluminosilicate resistance to acid dissolution or lowering the ph of the liquid film on airborne ash altogether our findings highlight that differing fe speciation in the ash bulk and surface reflecting its magmatic and eruptive history exerts a strong influence on the fe release behaviour of ash even from the same volcano the relative importance of bulk versus surface controls on fe mobilisation from ash during atmospheric transport will ultimately depend on the duration of contact with acids before deposition to the ocean