classification of huminite iccp system 1994 abstract in the new classification iccp system 1994 the maceral group huminite has been revised from the previous classification iccp 1971 int handbook coal petr suppl to 2nd ed to accommodate the nomenclature to changes in the other maceral groups especially the changes in the vitrinite classification iccp 1998 the new vitrinite classification iccp system 1994 fuel 77 349 358 the vitrinite and huminite systems have been correlated so that down to the level of sub maceral groups the two systems can be used in parallel at the level of macerals and for finer classifications the analyst now has according to the nature of the coal and the purpose of the analysis a choice of using either of the two classification systems for huminite and vitrinite this is in accordance with the new iso coal classification that covers low rank coals as well and allows for the simultaneous use of the huminite and vitrinite nomenclature for low rank coals

maturation and bulk chemical properties of a suite of solid hydrocarbons abstract in this paper we present strong correlations of solid hydrocarbon reflectance shro to vitrinite reflectance vro and bulk chemical properties aromaticity tmax h c etc these correlations suggest that like kerogen in coals and sedimentary rocks solid hydrocarbons vary systematically during maturation as a consequence shro is especially useful as a maturity indicator in rocks lacking vitrinite such as pre devonian rocks and many organic rich marine rocks unlike other organic maturationv indicators the utility of solid hydrocarbons is not limited by botanical evolution but rather the generative potential of the petroleum system solid hydrocarbons also known as solid bitumen asphalt dead oil migrabitumen and pyrobitumen are genetically defined as solid phase accumulations of predominantly hydrocarbons produced by petroleum generation in source rocks they may occur over a range of concentrations in outcrop and well samples in all components of petroleum systems although accumulations of solid hydrocarbons from exhumed reservoirs are well reported the extent and utility of disseminated solid hydrocarbons in shales is less understood solid hydrocarbons are found in organic rich to very lean mature rocks as a residual product of generation disseminated solid hydrocarbons exhibit three optical forms anisotropic coked granular and relatively uniform homogenous only the homogenous solid hydrocarbons are recommended for correlation purposes with other thermal indicators

solid bitumen reflectance and rock eval tmax as maturation indices an example from the nordegg member western canada sedimentary basin abstract marine organic rich rock units commonly contain little for vitrinite reflectance v r 0 measurement the most commoly used method of assessing thermal maturity this is true of the lower jurassic nordegg member a type i ii sulphur rich source rock from the western canada sedimentary basin this study examines the advantages and pitfalls associated with the use of rock eval t max and solid bitumen reflectance b r 0 to determined maturity in the nordegg vitrinite reflectance data from cretaceous coals and known coalification gradients in the study area are used to extrapolate v r 0 values for the nordegg t max increases non linearly with respect to both b r 0 and extrapolated v r 0 values a sharp increase in the reflectaance of both solid bitumen and vitrinite occurs between t max 440 450 c and is coincident with a pronounced decrease in hydrogen index values and the loss of solid bitumen and telalginite fluorescence over the same narrow t max interval this t max range is interpreted as the main zone of hydrocarbon generation in the nordegg and corresponds to extrapolated v r 0 values of 0 55 0 85 the moderate to high sulphur contents in the kerogen played a significant role in determining the boundaries of the nordegg oil window a linear relationship between b r 0 and extrapolated v r 0 as proposed elsewhere is not true for the nordegg b r 0 increases with respect to extrapolated v r 0 according to jacob s 1985 formula v r 0 0 618 b r 0 0 40 up to v r 0 0 72 b r 0 0 52 beyond this point b r 0 increases sharply relative to extrapolated v r 0 according to the relatioship v r 0 0 277 b r 0 0 57 r 2 0 91 the break in the b r 0 v r 0 curve at 0 72 v r 0 is thought to signifiy the peak of hydrocarbon generation and represents a previously unrecognized coalification jump in the solid bitumen analogous to the first coalification jump of liptinites

organic petrography of leonardian wolfcamp a mudrocks and carbonates midland basin texas the fate of oil prone sedimentary organic matter in the oil window abstract to better understand evolution of oil prone sedimentary organic matter to petroleum and expulsion from source rock we evaluated organic petrographic features of leonardian wolfcamp a repetitive siliceous and calcareous mudrock and fine grained carbonate lithofacies cycles occurring in the r ricker 1 core from reagan county midland basin texas the objectives of the petrographic investigation were to estimate thermal maturity identify organic matter types and abundances and identify the presence or absence of migrated hydrocarbons in organic lean carbonate layers an integrated analytical program included geochemical screening total organic carbon toc content by leco programmed pyrolysis by hydrocarbon analyzer with kinetics hawk including analysis of solvent extracted samples x ray diffraction mineralogy organic petrography scanning electron microscopy with energy dispersive spectroscopy sem eds including correlative light and electron microscopy clem and micro fourier transform infrared spectroscopy ftir analyses of solid bitumen the data indicate all samples are early to middle oil window thermal maturity with solid bitumen reflectance bro values of 0 55 0 86 and tmax of 440 455 c organic matter is predominantly solid bitumen as identified by optical microscopy in all lithofacies with minor contributions from inertinite solid bitumen abundance decreases from siliceous mudrock toc 3 0 wt to calcareous mudrock toc 1 0 to 3 0 wt to fine grained carbonate toc

sequence stratigraphic and genetic aspects of the tournaisian liegender alaunschiefer and adjacent beds this study reports the results of interdisciplinary investigations of tournaisian deposits from the german rheinisches schiefergebirge and provides a genetic and sequence stratigraphic interpretation microfacies and geochemical data confirm normal marine outer shelf to slope environments for the lower tournaisian hangenberg formation in contrast data from the condensed phosphatic liegender alaunschiefer black shale indicate low current energy and anoxic conditions in the sediment and the water column we suggest that anoxia was caused by eutrophication and high organic productivity due to factors such as upwelling a climate related improvement of oceanic ventilation and volcanic nutrient input the hangenberg formation represents the lowstand through the early transgressive systems tract of a third order depositional sequence while the liegender alaunschiefer is a late transgressive systems tract and maximum flooding deposit the richrath limestone was deposited during the highstand systems tract thus quickly rising sea level and eutrophication may account for the peculiar and uniform facies of the liegender alaunschiefer

fold reactivation involving angular unconformable sequences theoretical analysis and natural examples from the cantabrian zone northwest spain abstract during the reactivation of folds truncated by unconformable layers the unconformity surface adopts various geometrical shapes depending on the fold reactivation mechanisms the paleorelief slope is also a determining factor for location and development of cover structures it can be theoretically shown that the reactivation of flexural flow and flexural slip folds below an unconformity produces folds of the same sense of curvature in layers above and below the unconformity viewed in profile that is to say these mechanisms give rise to a cover synform over a basement synform or antiform over antiform when the axes of both folds are subhorizontal folds reactivated by tangential longitudinal strain also behave in the same way in this case the cover folds may become tight even for initially high angles of unconformity which does not happen with flexural mechanisms the reactivation of chevron folds may give rise to opposite curvatures of basement and cover beds hence paradoxical structures such as a cover synform over a basement antiform or viceversa may be produced even if their axes are horizontal when two adjacent parts of the basement sequence are deformed by different folding mechanisms cover beds and unconformity are folded over the homoclinal sequence of each limb in the basement fold during fold reactivation the unconformity surface usually becomes a surface of decollement owing to the structures that have to be developed in the cover in order to accommodate the changes in length of the unconformity the development of extensional or compressional structures in the cover can be predicted from a geometrical study of the unconformity surface natural examples of reactivated folds under unconformable sequences of carboniferous age in the cantabrian zone show a good agreement with the above mentioned theoretical conclusions conclusions obtained on the distribution of folding mechanisms in the limbs and hinge zones and in layers or multilayers of different nature from the geometrical study of folded unconformable sequences in the cantabrian zone also agree with results from published experimental data

towards radiocarbon calibration beyond 28 ka using speleothems from the bahamas we present a new speleothem record of atmospheric 14c between 28 and 44 ka that offers considerable promise for resolving some of the uncertainty associated with existing radiocarbon calibration curves for this time period the record is based on a comprehensive suite of ams 14c ages using new low blank protocols and u th ages using high precision mc icpms procedures atmospheric 14c was calculated by correcting 14c ages with a constant dead carbon fraction dcf of 22 7 5 9 based on a comparison of stalagmite 14c ages with the intcal04 reimer et al 2004 calibration curve between 15 and 11 ka the new 14c speleothem record shows similar structure and amplitude to that derived from cariaco basin foraminifera hughen et al 2004 2006 and the match is further improved if the latter is tied to the most recent greenland ice core chronology svensson et al 2008 these data are however in conflict with a previously published 14c data set for a stalagmite record from the bahamas gb 89 24 1 beck et al 2001 which likely suffered from 14c analytical blank subtraction issues in the older part of the record the new bahamas speleothem 14c data do not show the extreme shifts between 44 and 40 ka reported in the previous study beck et al 2001 causes for the observed structure in derived atmospheric 14c variation based on the new speleothem data are investigated with a suite of simulations using an earth system model of intermediate complexity data model comparison indicates that major fluctuations in atmospheric 14c during marine isotope stage 3 is primarily a function of changes in geomagnetic field intensity although ocean atmosphere system reorganisation also played a supporting role

pervasive dolomitization with subsequent hydrothermal alteration in the clarke lake gas field middle devonian slave point formation british columbia canada the clarke lake gas field in british columbia canada is hosted in pervasively dolomitized middle devonian carbonates of the slave point formation the clarke lake field consists mostly of pervasive matrix dolomite and some saddle dolomite the latter varying in volume from about zero in limestones to normally 20 40 locally up to 80 in dolostones over any given 10 m 33 ft core interval some of the saddle dolomite is replacive some is cement and both varieties are associated with dissolution porosity and recrystallized matrix dolomite the major objective of this study is to identify the causes and timing of matrix and saddle dolomite formation specifically whether these dolomites are hydrothermal a comprehensive petrographic and geochemical examination indicates that pervasive matrix dolomitization was accomplished by long distance migration of halite saturated brines during the late devonian to mississippian fluid inclusion homogenization temperatures suggest about 150 uncorrected to 190c corrected at the time of matrix dolomitization these temperatures differ markedly from most published work on the dolomitized devonian reefs in the alberta basin south of the peace river arch where pervasive matrix dolomitization was accomplished by advection of slightly modified seawater at temperatures of about 60 80c and where no hydrothermal influence was ever present the saddle dolomites at clarke lake are not cogenetic with matrix dolomite and are not the product of hydrothermal dolomitization sensu stricto instead they formed through the hydrothermal alteration of matrix dolomite by way of invasion of a gypsum saturated brine during periods of extremely high heat flow and regional plate margin tectonics in the late devonian to mississippian fluid inclusion homogenization temperatures suggest that hydrothermal alteration occurred between 230 uncorrected and 267c corrected which is significantly higher than the maximum temperature of about 190c attained by the slave point formation during burial the sources of the halite and gypsum saturated brines are middle devonian evaporite depositional environments roughly 200 km 124 mi south and or east of clarke lake near the peace river arch

upper devonian mississippian stratigraphic framework of the arkoma basin and distribution of potential source rock facies in the woodford chattanooga and fayetteville caney shale gas systems wireline logs were used to document the stratigraphic framework of upper devonian mississippian strata in the arkoma basin and maps of high gamma ray hgr log response were used to analyze the spatial distribution of potential source rocks in the woodford chattanooga and fayetteville caney shale gas systems the woodford chattanooga shale is a transgressive deposit that accumulated on an arid continental margin influenced by marine upwelling and minimal sediment influx a broad hgr depocenter along the southwestern margin of the basin includes two areas of higher accommodation containing the thickest hgr concentrations basin wide patterns of hgr likely reflect broad tectonic influence on accommodation the proportion of chert in the formation increases eastward and southward likely reflecting latitudinal and bathymetric influence on the accumulation of siliceous ooze the lower mississippian burlington sequence which lies between the two shale gas systems comprises carbonate ramp and distal shale deposits proximal ramp facies form an apron around the southern flank of the ozark uplift and grade radially basinward into distal facies an upper mississippian succession in the east includes lowstand deposits of the batesville delta which onlap the relict burlington ramp basinwide the succession includes the transgressive fayetteville caney shale overlain by regressive deposits of the proximal pitkin limestone and distal upper fayetteville arkansas and false caney oklahoma shale the hgr shale is concentrated in an area of intermediate accommodation on the western margin of the mississippi embayment and just basinward of the pitkin limestone pinchout in arkansas and in an area of relatively high accommodation in oklahoma

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

post oil solid bitumen network in the woodford shale usa a potential primary migration pathway abstract an important if not predominant component of porosity in many gas shales has been identified in organic matter an organic network in shales has been described in the literature as organic matter generalized term kerogen primary or bitumen secondary recognition of the type and origin of an organic network in shales has relevance in establishing the origin and timing of porosity and fracture development the pervasive nature of the organic network adopting the shape of pores in type ii kerogen rich woodford shale suggests it is the residue of primary oil migration we use the term post oil solid bitumen to distinguish this bitumen occurrence from pre oil solid bitumen defined as a precursor of oil three forms of this post oil solid bitumen network are recognized in reflected white light at 500 magnification and confirmed in backscattered scanning electron microscope images at 2500 magnification namely speckled 1 2 m wispy 2 5 m and connected 5 m the post oil solid bitumen network demonstrates the prior occurrence of oil generation and migration within this hydrocarbon source rock provides porosity for hydrocarbon storage sites and forms hydrocarbon migration pathways

detection of natural weathering of upper mcalester coal and woodford shale oklahoma u s a abstract natural weathering refers to the natural oxidation of organic and inorganic matter in rocks at the surface and in the shallow subsurface the objective of this study is to apply routine geochemical analyses including organic petrography to coal and shale samples extending from the weathered to unaltered zones to illustrate the effects of weathering on organic matter in coal and shale some significant observations from the upper mcalester coal and the woodford shale are 1 a sulfate index si using sulfur form analysis data that reveals the transformation of pyrite to sulfate minerals is a very sensitive weathering indicator it increased in weathered samples 2 rock eval pyrolysis data such as hydrogen index hi and oxygen index oi are very sensitive to weathering oi hi increased in weathered samples 3 vitrinite reflectance decreased in weathered samples and 4 petrographic signs of weathering include microfractures pitted surface dark reaction rims and high relief sulfate index and petrographic signs of weathering should be used on surface and shallow subsurface rock samples as an indication of the extent of weathering the validity of other analyses can then be evaluated accordingly

a field study of the chemical weathering of ancient sedimentary organic matter weathering profiles developed on organic carbon rich black shales were studied to examine the loss and degradation of organic matter om during weathering and its role in the geochemical carbon cycle analysis of weathered shales reveals between 60 and nearly 100 total organic carbon toc loss in highly weathered samples relative to initial unweathered toc content pyrite loss coincides with or precedes organic carbon loss elemental analysis and flash pyrolysis gas chromatography py gc of kerogen concentrates indicate that there is little or no selective enrichment or depletion of norg containing sorg containing alkylaromatic branched alkyl or long chain n alkyl moieties in most profiles during weathering kerogen o c ratios consistently increase with toc and pyrite loss infrared spectroscopy ir reveals an increase in the relative abundance of c c and c o bonds relative to alkyl c h bonds in progressively weathered samples these results suggest a two component model for kerogen weathering largely non selective oxidation and hydration followed by cleavage dissolution of oxidized kerogen fragments the extent of weathering in a given outcrop is likely limited by a combination of the rate of physical erosion and exposure of the rock to oxidizing surface waters with om type composition playing a lesser role

a global model for cave ventilation and seasonal bias in speleothem paleoclimate records cave calcite deposits speleothems provide long and continuous records of paleoenvironmental conditions in terrestrial settings typical environmental proxy measurements include speleothem growth rate and variations in elemental and isotope geochemistry commonly the assumption is made that speleothems grow continuously and at a constant rate throughout the year however seasonal variation of growth rate may be the rule in many caves here we apply observations of modern calcite growth and cave air co2 concentrations and a model of factors controlling cave ventilation to construct a global model predicting where cave calcite growth may be seasonal previous models and measurements of calcite precipitation in caves demonstrate the retardation of speleothem growth by high cave air co2 elevated co2 is commonly dissipated by ventilation driven by density differences between cave and surface air seasonal cycles in atmospheric temperature pressure and humidity commonly drive these density contrasts modeling these changes latitudinally and globally indicates a geographic control on seasonal cave ventilation and thus on a principal controlling factor of speleothem growth the model predicts that given constant water calcium and co2 inputs speleothems from temperate to boreal continental regions commonly accumulate more calcite in the cool season and less or none in the warm season these models predict that proxies from temperate to boreal speleothems may be seasonally biased due to seasonal ventilation whereas tropical and maritime records should not

mineralogy and geochemistry of mississippian and lower pennsylvanian black shales at the northern margin of the variscan mountain belt germany and belgium abstract exploration of unconventional gas resources from paleozoic formations in northwestern germany is just getting started large potential gas reservoirs are presumed to be present north of the rhenish massif where mississippian and pennsylvanian marine black shales occur this paper comprises geochemical and mineralogical data and other important aspects of potentially economic black shale formations of the carboniferous additionally the burial and thermal history was reconstructed using 1d modeling software schlumberger these 1d models were calibrated with vitrinite reflectance data from outcrops and shallow wells in general all paleozoic black shales are at present highly mature between about 1 5 and 3 vitrinite reflectance the shales of the uppermost mississippian upper alum shale chokier formation have high contents of organic carbon are tens of meters thick and can be regarded as potential gas shale targets most other mississippian and pennsylvanian black shales are relatively thin adjacent carbonates are often stained black and rich in solid bitumen indicating former oil impregnation of these reservoirs

interpreting benthic oxygen levels in mudrocks a new approach quantified paleoecology and gamma ray spectrometry have been applied in the analysis of the kimmeridge clay a highly organic rich british jurassic mudrock decreasing benthic oxygen trends are reflected in decreasing species richness and dominance diversity values similarly the degree of fragmentation of the benthos reflects the benthic energy levels and covaries with benthic oxygen the calculation of authigenic uranium values from data gathered by gamma ray spectrometry shows enrichment in more oxygen deficient environments the good correlation between the independently derived paleoecological and authigenic u data indicates the importance of these techniques in environmental analysis of marine petroleum source rocks

kinematics of orocline tightening in the core of an arc paleomagnetic analysis of the ponga unit cantabrian arc northern spain 1 paleomagnetic and structural analyses of the western european variscan belt wevb suggest that the most viable kinematic model for variscan deformation in northern iberia is oroclinal bending of an originally linear belt in a two stage tectonic history this history represents two regional compression phases e w in the late carboniferous and n s in the permian both in present day coordinates which resulted in the refolding about steeply plunging axes of initially north south trending thrusts and folds in the hinge zone and oroclinal tightening due to vertical axis rotation of the belt s limbs however the orocline model has yet to be critically tested in the wevb s core this study reports new paleomagnetic rock magnetic and structural data from the inner core of the wevb in order to test opposing kinematic models for the well documented fault and fold interference structures formed by late stage variscan deformation and to better understand the overall development of the wevb arc map scale structural features within the wevb core have a highly sinuous geometry characterized by transverse and thrust parallel fold systems formed by fault bend folding over footwall ramps the intersections of these two fold systems produce steeply plunging interference folds which are best exposed in the ponga thrust unit a total of 67 paleomagnetic sites were collected in the barcaliente formation of the ponga unit with emphasis placed on detailed spatial coverage of individual structural domains a multicomponent paleomagnetic remanence was measured which is interpreted to be composed of two components a low unblocking temperature recent viscous magnetization and a high unblocking temperature ancient magnetization that was acquired in the latest stephanian to early permian after initial d1 thrusting and folding bur prior to major secondary rotation rock magnetic experiments show that the characteristic remanence magnetization is carried by secondary authigenic pseudosingle domain magnetite these paleomagnetic results are used to determine the kinematics and geometry of postmagnetization deformation by restoring in situ magnetic vectors back to a defined reference direction on the basis of the restored ponga unit geometry the steeply plunging interference folds found in the wevb core are best described by a combination of secondary buckling of frontal ramp parallel hanging wall anticlines and modification of d1 lateral oblique ramps as frontal ramps during late stage north south shortening this combination of structural modification of the inner core of the wevb was necessary to accommodate oroclinal bending during the final amalgamation of pangea in the late paleozoic

relationship between modern rainfall variability cave dripwater and stalagmite geochemistry in guam usa 1 modern rainwater cave dripwater and cave stalagmite geochemical time series from a cave in guam 13 38 n 144 53 e are used to better understand how changes in cave stalagmite geochemistry relate to aboveground changes in rainfall at a tropical location a scientific field team based in guam collects monthly samples from multiple sites for geochemical analyses at a cave and aboveground rainfall from a nearby location we compute a transfer function between rainfall amount and oxygen isotopic composition 18o of a decrease increase of 0 94 0 3 m year for every 1 increase decrease in rainfall 18o based on data extracted from the international atomic energy agency iaea global networks of isotopes in precipitation gnip database and from data generated in this study dripwater 18o and mg ca ratios show annual cyclicity at some but not all sites accentuating the complex nature of cave hydrology a stalagmite 18o record for the last 160 years indicates the existence of droughts of decadal length when rainfall is estimated to be 0 65 0 3 m year less than average conditions this estimate of rainfall reduction most likely refers to wet season months as these months preferentially contribute to groundwater recharge the proxy based climate record at guam provides new evidence highlighting how a rainy site in the western pacific warm pool today can experience considerable changes in rainfall on decadal timescales

relationship between petroleum composition and depositional environment of petroleum source rocks crude oils of nonmarine source can be distinguished from those of marine shale source and from oils originating in marine carbonate sequences by using a battery of geochemical parameters as demonstrated with a sample suite of nearly 40 oils a novel parameter based on the presence of c30 steranes in the oil was found to be a definitive indication of a contribution to the source from marine derived organic matter a second novel parameter based on monoaromatized steroid distributions was effective in helping to distinguish nonmarine from marine crudes and can be used to gauge relative amounts of higher plant input to oils within a given basin sterane distributions were similarly useful for detecting higher plant input but were less effective than monoaromatize steroid distributions for making marine versus nonmarine distinctions concentrations of high molecular weight paraffin can also be effective nonmarine indicators but are influenced by maturation and biodegradation processes certain algal derived nonmarine oils may show little high molecular weight paraffin response oils from carbonate sources with a few exceptions can be distinguished by having low pristane phytane ratios low carbon preference indexes and high sulfur contents gammacerane indexes and carbon isotope ratios of the whole crude are not effective in distinguishing these types of environmental differences on a global basis

trace metal and carbon isotopic variations in cave dripwater and stalagmite geochemistry from northern borneo we investigate stalagmite trace metal ratios and carbon isotopic composition 13 c as potential paleoclimate proxies by comparing cave dripwaters stalagmites and bedrock composition from gunung mulu and gunung buda national parks in northern borneo a tropical rainforest karst site three year long biweekly time series of dripwater mg ca sr ca and 13 c from several drips at our site are not correlated with rainfall variability indicative of a relatively weak relationship between hydroclimate and dripwater geochemistry at our site however combining all of the dripwater geochemical data gathered over four field trips to our site n 300 samples we find that drips with highly variable mg sr ca have relatively invariable 18 o values close to the mean we hypothesize that increased residence times translate into reduced variance in dripwater 18 o through mixing in the epikarst as well as increased mg sr ca values through increased calcite precipitation in the epikarst mg ca sr ca and 13 c time series from three overlapping stalagmites that grew over the last 27 kyrs are characterized by strong centennial scale variations and bear little resemblance to previously published well reproduced 18 o time series from the same stalagmites the only shared signal among the three stalagmites geochemical time series is a relative decrease of 1 in 13 c from the last glacial maximum to the holocene consistent with a transition from savannah c4 to rainforest c3 conditions documented in nearby records taken together our study indicates that stalagmite mg sr ca ratios are poor indicators of hydroclimate conditions at our site while stalagmite 13 c exhibits some reproducible signals on glacial interglacial timescales

the world s by product and critical metal resources part i uncertainties current reporting practices implications and grounds for optimism abstract many of the metals extracted as by products and rated as critical are vital to important modern technologies but are seldom reported as extractable commodities by the mining industry this creates numerous uncertainties and challenges in estimating the global resources of these metals here we outline the current approaches or lack thereof used in resource reporting and identify and discuss the uncertainties surrounding critical co and by product reporting in detail we present a review of ore reserve and mineral resource reporting in the mining industry including the identification of various methods by which resource accounts have been constructed a discussion of examples and differences between countries states and organisations that conduct these assessments and a discussion of the various ways in which these resource data have been interpreted this is followed by a series of case studies that document and discuss the reporting of selected critical metals that suggest that the lack of reporting is dominantly as a result of the perceived or actual low monetary value of by products at the mine site rather than as a result of any lack of these metals indicating that different types of uncertainties can arise in estimating the global resources of these critical commodities this paper also addresses and continues in parts ii and iii the numerous issues and uncertainties identified in this study by outlining approaches and alternative data sources that can be used to develop more comprehensive assessments of critical metal resources from deposit to global levels the hybrid methodologies proposed in this paper provide reasons for some optimism in that by product and critical metal resources can still be identified to a reasonable degree of accuracy and these resources are likely to be sufficient to meet demand for some decades however there is still a strong case for improved reporting of by products and critical metals in mineral deposits to assist in these efforts and to clarify the true global position in terms of the future security of supply of co and by product metals invariably including the critical or e tech metals

solid bitumen occurrences in the arruda sub basin lusitanian basin portugal petrographic features abstract the middle jurassic to cretaceous sedimentary record in the lusitanian basin portugal reveals the presence of disseminated solid bitumen the present work is focused on the petrographic characteristics of solid bitumen identified in the freixial 1 and benfeito 1 boreholes arruda sub basin lusitanian basin that display different thermal maturities microscopy techniques reflected and transmitted white light incident blue light and sem and organic geochemistry analyses total organic carbon total sulfur and insoluble residue were used to study these samples from the results obtained by optical microscopy fluorescence and reflectance it was possible to distinguish three types of solid bitumen they were labeled as solid bitumen a present in all the samples solid bitumen b and solid bitumen c these ones observed in some of them they correspond to allochthonous migrated bitumens in blue incident light some bitumen do not show fluorescence while others reveal fluorescence that range from yellow solid bitumen b to dark brown solid bitumen a all bitumens are optically isotropic bitumen reflectance varies between 0 70 and 2 60 r r and the vitrinite reflectance ranges from 1 11 to 1 48 r r based on the r r values the solid bitumen identified in these samples are classified as impsonite epi and cata or pyrobitumen no relation can be established with confidence for the reflectance of bitumens with the reflectance of vitrinite

development of organic porosity in the woodford shale with increasing thermal maturity abstract using a combination of focused ion beam milling and scanning electron microscopy we describe the evolution of secondary organic porosity in eight woodford shale late devonian early mississippian samples with mean random vitrinite reflectance values ranging from 0 51 ro to 6 36 ro organic porosity was observed to be absent in samples with vitrinite reflectance values of up to 0 90 ro with the first appearance of secondary pores starting with the 1 23 ro sample porosity in the organic matter was unexpectedly absent in a sample with a vitrinite reflectance of 2 00 ro however organic pores were again found in samples with higher thermal maturities porosity when present did not appear to be uniformly distributed among the organic matter that was within less than a micron of each other suggesting important differences in composition of the organic matter thin regions of organic matter were observed between grains raising the possibility that small amounts of the deposited organic matter were compacted between grains to form thin layers and or the structures are part of the secondary organic matter interpreted to be post oil bitumen which was left behind as a residue during oil migration through the shale some regions of porous organic matter appeared to be grain protected whereas others did not which indicates that these non protected porous organic regions may be stress supporting with porosity intact under in situ reservoir conditions these observations suggest that thermal maturity alone is insufficient to predict porosity development in organic shales and other factors such as organic matter composition complicate porosity development

petrographic and geochemical characterization of organic rich mississippian black shales in the north of spain vegamian formation cantabrian zone abstract black shales 1 60 m thick with minor cherts radiolarites and phosphate nodules of mississippian age middle upper tournaisian vegamian formation occur in the fold and thrust belt of the cantabrian zone n spain at the base of the carboniferous succession which is infilling the variscan foreland basin the vegamian formation was accumulated in a similar sedimentary and paleogeographic context to the upper devonian carboniferous black shales of the appalachian arkoma fort worth western canada and antler foreland basins north america and to the variscan foreland basin in belgium and germany five stratigraphic sections were investigated in the southern branch of the cantabrian zone corresponding to the shallower sectors of the passive margin of the variscan foreland basin in n spain where this stratigraphic unit reaches a thickness of generally the organic matter is dominated by bitumen found either as diffuse masses or concentrated in spaces and cavities often parallel to the bedding planes or filling voids within calcite veins and fractures generally the bitumen masses are homogeneous without secondary porosity but occasionally they show mosaic optical texture indicating thermal transformation anastomosing structures likely related to bituminite are also common and exhibit a large range of reflectances autochthonous organic matter algae bacteria is seen as scarce tasmanites and liptodetrinite whereas allochthonous components vitrinite inertinite are also scarce except in the olleros section the range of reflectances of vitrinite like particles is similar to that of bitumen but the identification is uncertain and therefore the reflectance of bitumen brr has been used for thermal maturity assessment a gaussian like distribution of bitumen reflectances was found for la brana section brr 0 70 whereas a bimodal distribution was observed in olleros brr 0 70 and vegamian sections brr 0 95 and large scatter of readings in millaro brr 1 55 the vitrinite reflectance equivalent estimated from aromatic compounds indicates that most of the existing correlations between vitrinite and bitumen reflectances underestimate the maturity of the lowest reflecting sections and overestimate it in the highest reflecting one ts toc ratios the geochemistry of organic matter and spectral gamma ray measurements suggest a normal marine to dysoxic environment of deposition with only local anoxia at the base of the vegamian formation

polyphase thermal evolution in the infra cambrian ara group south oman salt basin as deduced by maturity of solid reservoir bitumen petrographic and organic geochemical analyses on solid reservoir bitumen from the late precambrian to early cambrian ara group indicate polyphase thermal evolution in the south oman salt basin sosb the ara group constitutes a complex petroleum system in the deep subsurface 3 5 km of interior oman salt diapirs encase isolated partly highly overpressured carbonate bodies intra salt stringers which represent a predominantly self charging hydrocarbon system a large number of stringer cores show that reservoir quality is decreased by the presence of solid reservoir bitumen by using different microscopy techniques this solid reservoir bitumen has been identified within pores pore throats and microfractures of the carbonates solid bitumen reflectance measurements brr were converted to vitrinite reflectance vrr using a new improved calibration vitrinite reflectance geothermometry shows that maximum paleo temperatures have a highly heterogeneous distribution paleo temperatures of 380 c were obtained from coke like solid reservoir bitumen which most likely formed from thermal cracking of oil in our model this process is related to hydrothermal fluids deriving from deeper pre salt strata of the sosb which entered the intra salt carbonate stringers during times of basement tectonic activity via hydrofractures this caused the formation of high maturities pyrobitumens in close vicinity to the fractures and precipitation of migrabitumens with increasing distance to the ht source which is supported by the geochemical composition of the solid reservoir bitumens the influx of these fluids into the carbonate stringers is considered to represent a major contribution to their strong overpressures 2007 elsevier ltd all rights reserved

petrographic maturity parameters of a devonian shale maturation series appalachian basin usa iccp thermal indices working group interlaboratory exercise abstract this paper presents results of an interlaboratory exercise on organic matter optical maturity parameters using a natural maturation series comprised by three devonian shale samples huron member ohio shale from the appalachian basin usa this work was conducted by the thermal indices working group of the international committee for coal and organic petrology iccp commission ii geological applications of organic petrology this study aimed to compare 1 maturation predicted by different types of petrographic parameters vitrinite reflectance and spectral fluorescence of telalginite 2 reproducibility of the results for these maturation parameters obtained by different laboratories and 3 improvements in the spectral fluorescence measurement obtained using modern detection systems in comparison with the results from historical round robin exercises mean random vitrinite reflectance measurements presented the highest level of reproducibility group standard deviation 0 05 for low maturity and reproducibility diminished with increasing maturation group standard deviation 0 12 corrected fluorescence spectra provided by 14 participants showed a fair to good correspondence standard deviation of the mean values for spectral parameters was lowest for the low maturity sample but was also fairly low for higher maturity samples a significant improvement in the reproducibility of corrected spectral fluorescence curves was obtained in the current exercise compared to a previous investigation of toarcian organic matter spectra in a maturation series from the paris basin this improvement is demonstrated by lower values of standard deviation and is interpreted to reflect better performance of newer photo optical measuring systems fluorescence parameters measured here are in good agreement with vitrinite reflectance values for the least mature shale but indicate higher maturity than shown by vitrinite reflectance for the two more mature shales this red shift in max beyond 0 65 vitrinite reflectance was also observed in studies of devonian shale in other basins suggesting that the accepted correlation for these two petrographic thermal maturity parameters needs to be re evaluated a good linear correlation between max and tmax for this maturation series was observed and max 600 nm corresponds to tmax of 440 c nevertheless if a larger set of devonian samples is included the correlation is polynomial with a jump in max ranging from 540 to 570 nm up to 440 c of tmax the max mostly reaches up to 500 nm beyond a tmax of 440 c max is in the range of 580 600 nm this relationship places the red shift when the onset of the oil window is reached at tmax of 440 c moreover the correlation between hi and max r2 0 70 shows a striking inflection and decrease in hi above a max of 600 nm coincident with the approximate onset of hydrocarbon generation in these rocks

carbon sulfur plots to show diagenetic and epigenetic sulfidation in sediments abstract organic carbon vs sulfide sulfur plots are now being used regularly by many geochemists to help understand recent and ancient depositional environments and diagenetic processes usually these plots are useful to recognize nonmarine vs marine environments or oxic vs anoxic vs euxinic depositional environments however c vs s plots can also indicate diagenetic and epigenetic events that produce excess sulfide four new examples are presented and discussed

unconventional shale gas systems the mississippian barnett shale of north central texas as one model for thermogenic shale gas assessment shale gas resource plays can be distinguished by gas type and system characteristics the newark east gas field located in the fort worth basin texas is defined by thermogenic gas production from low porosity and low permeability barnett shale the barnett shale gas system a self contained source reservoir system has generated large amounts of gas in the key productive areas because of various characteristics and processes including 1 excellent original organic richness and generation potential 2 primary and secondary cracking of kerogen and retained oil respectively 3 retention of oil for cracking to gas by adsorption 4 porosity resulting from organic matter decomposition and 5 brittle mineralogical composition the calculated total gas in place gip based on estimated ultimate recovery that is based on production profiles and operator estimates is about 204 bcf section 5 78 10 9 m 3 1 73 10 4 m 3 we estimate that the barnett shale has a total generation potential of about 609 bbl of oil equivalent ac ft or the equivalent of 3657 mcf ac ft 84 0 m 3 m 3 assuming a thickness of 350 ft 107 m and only sufficient hydrogen for partial cracking of retained oil to gas a total generation potential of 820 bcf section is estimated of this potential approximately 60 was expelled and the balance was retained for secondary cracking of oil to gas if sufficient thermal maturity was reached gas storage capacity of the barnett shale at typical reservoir pressure volume and temperature conditions and 6 porosity shows a maximum storage capacity of 540 mcf ac ft or 159 scf ton

thermal maturity of woodford shale gas and oil plays oklahoma usa abstract being a hydrocarbon source rock and having a brittle silica rich lithologic character makes the woodford shale late devonian to early mississippian an important oil and gas shale in oklahoma since 2004 woodford shale plays have expanded from producing primarily thermogenic methane in one geologic province to producing thermogenic methane condensate oil and biogenic methane in four geologic provinces at thermal maturities from mature 0 5 vitrinite reflectance ro to post mature 2 to 3 ro condensate is produced at a thermal maturity up to 1 67 ro oil is produced from naturally fractured silica rich shale biogenic methane is produced in shallow

testing reproducibility of vitrinite and solid bitumen reflectance measurements in north american unconventional source rock reservoir petroleum systems abstract an interlaboratory study ils was conducted to test reproducibility of vitrinite and solid bitumen reflectance measurements in six mudrock samples from united states unconventional source rock reservoir petroleum systems samples selected from the marcellus haynesville eagle ford barnett bakken and woodford are representative of resource plays currently under exploitation in north america all samples are from marine depositional environments are thermally mature tmax 445 c and have moderate to high organic matter content 2 9 11 6 wt toc their organic matter is dominated by solid bitumen which contains intraparticle nano porosity visual evaluation of organic nano porosity pore sizes 1 0 produced lowest r values generally 0 5 absolute reflectance similar to a prior ils for similar samples other traditional approaches to outlier removal outside mean 1 5 interquartile range and outside f10 to f90 percentile range also produced similar r values standard deviation values

significance of coniferous rain forests and related organic matter in generating commercial quantities of oil gippsland basin australia contrary to the conventional belief that humic coal generates primarily gas 3 billion bbl of recoverable oil has been discovered in the humic coaly succession of the fluviodeltaic latrobe group upper cretaceous tertiary that serves as both the reservoir and the source for hydrocarbons in the offshore gippsland basin of southeastern australia evidence for generation of liquid hydrocarbons from the coaly succession includes 1 similarity of n alkane distribution in the oil and in the coal extracts 2 high wax content of oil up to 27 by weight 3 high ratio of pristane phytane in oil 5 6 and 4 dominance of c29 steranes in the oil in the gippsland basin coniferous rain forests dominated by kauri vegetation flourished in a raised bog setting present temperate climate and kauri vegetation of new zealand are considered to be the modern analog to the gippsland basin the coniferous vegetation provided large quantities of hydrogen rich exinite macerals such as cutinite and resinite with potential to generate oil high rainfall raised ground water level low oxygen high acidity and low nutrient conditions of a raised bog setting were suitable for preserving organic matter a comparison of gas chromatograms of oils in the gippsland basin with gas chromatograms of oils generated by hydrous pyrolysis in the laboratory from the immature source rocks suggests that the paraffinic fraction of the oil was derived from coal and the naphthenic fraction was derived chiefly from resin

bahamian speleothem reveals temperature decrease associated with heinrich stadials abstract temperature reconstructions across heinrich stadials 1 3 are presented from an absolute dated speleothem from abaco island in the bahamas to understand the nature of climate change across these intervals in the subtropical atlantic the stalagmite carbonate record dated by the u th geochronometry technique includes higher 18o and 13c values within heinrich stadials 1 2 and 3 followed by rapid declines at the end of the stadials to aid in the interpretation of these results the 18o of fluid inclusions associated with the heinrich stadials were also analyzed these measurements which allowed for the relative influence of temperature and 18o of precipitation to be distinguished demonstrate minimal changes in the 18o of fluid inclusions suggesting that changes in the 18o values of the speleothem carbonate associated with heinrich stadials 1 3 are principally driven by an average 4 c temperature decrease rather than a change in the 18o of the rainfall hence rainfall amount these findings support previous work in the north atlantic and are consistent with the climate response to a weakening of the atlantic meridional overturning circulation

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

interpretation of speleothem calcite δ13c variations evidence from monitoring soil co2 drip water and modern speleothem calcite in central texas we studied the sources and transport of carbon in two active karst systems in central texas inner space cavern is and natural bridge north and south caverns nb to provide new insights into the interpretation of speleothem cave calcite deposit carbon isotope compositions we have determined the 13c values of soil co2 13cs in grassland and savanna above these caves with 13c values of cave drip water 13chco3 and modern speleothem calcite grown on artificial substrates 13ccc we compare 13chco3 values from direct drip sites where water was sampled immediately upon discharging from the cave ceiling to values from indirect sites where water was sampled after flowing along a prolonged path within the cave that allowed for longer co2 degassing and have found that direct drip sites yield consistently lower 13chco3 values the 13chco3 values of direct drip water below savanna 10 6 0 5 and 12 6 0 2 in nb and is respectively are indistinguishable from is or similar to nb calculated 13chco3 values in equilibrium with measured soil co2 beneath trees 13 5 to 11 3 for juniper trees above nb and 13 6 to 12 6 for mixed oak and elm trees above is respectively at is the 13chco3 values of direct drip water are higher below grassland 9 7 0 3 than below savanna 12 6 0 2 these results suggest that the 13chco3 values of drip waters that initially enter the caves are controlled by deep rooted plants where present and are minimally influenced by host rock dissolution and or prior calcite precipitation pcp the 13chco3 values of indirect drip water vary seasonally with relatively low values during the summer 10 8 0 8 and 9 2 0 4 under juniper savanna at nb and under grassland at is respectively that are similar to the direct drip 13chco3 values 10 6 0 5 and 9 7 0 3 under savanna at nb and under grassland at is respectively the relatively high 13chco3 values of indirect drip sites during the winter 13chco3 8 6 0 8 at nb and 8 0 0 1 at is result from co2 degassing of water along in cave flow paths we also present decade long records of modern calcite 13c values from direct and indirect drip sites at is the 13ccc values vary seasonally with lower values during the summer and higher values during the winter and with smaller amplitude variations at the direct drip site such seasonal variations can be used as a geochronological tool in some speleothems that do not contain visible lamina the summer 13ccc values of direct drip calcite are similar to 13ccc values predicted from soil co2 collected beneath trees above that drip site the occurrence of highest 13ccc values during the winter when cave co2 concentrations are low highlights the significance of ventilation driven changes in cave air pco2 modern calcite 13c values are also negatively correlated with drip rate which suggests that 13ccc variations are controlled by kinetic effects during degassing and calcite precipitation associated with the drip water exposure time to a low pco2 environment in all at the caves we investigated variability in speleothem 13ccc values primarily reflect presence absence of deep rooted vegetation and kinetic isotope effects we therefore infer that increased aridity may result in higher 13c values of vegetation lower drip rates and more drip water degassing and thus higher 13ccc values of speleothem calcite

application of aromatic compounds as maturity indicators in source rocks and crude oils concentration ratios of aromatic compounds such as naphthalenes phenanthrenes and dibenzothiophenes are at present attracting increasing attention as maturity indicators in sedimentary rocks and crude oils generally these indicators rely either on an increase with maturity in the degree of alkylation of a given parent compound or a shift in the isomer distribution of alkyl aromatic homologues towards thermally more stable isomers a combination of both concepts in the methylphenanthrene index mpi resulted in an excellent maturity parameter as demonstrated for rock extracts by an improved correlation with mean vitrinite reflectance rm between 0 65 and 1 4 i e in the zone of oil formation in cases that rm measurements were ambiguous this empirical relationship has proved useful in the calculation of theoretical vitrinite reflectance rc values from the mpi on the other hand for potential petroleum source rocks reaching maturity at relatively low temperatures the influence of the organic matter type on the aromatic distributions cannot be neglected consequently organic facies effects should be taken into account in the interpretation of aromatic distributions of such source rocks and related crude oils since the impact of the organic facies is strongly reduced with increasing maturity aromatic maturity parameters are particularly useful in the maturity evaluation of post mature crude oils and condensates in contrast to biological markers substantially higher concentrations of the key alkyl aromatics persist at elevated maturation levels thus aromatic maturity parameters should be considered as versatile tools in organic maturation studies and can complement established maturity indicators based on steranes and terpanes

quantification of loss of calcite pyrite and organic matter due to weathering of toarcian black shales and effects on kerogen and bitumen characteristics abstract comparison of geochemical data on posidonia shale early toarcian from a shallow unweathered core and from adjacent weathered exposures of the same fades was performed results revealed that quantitatively the most affected petrographic constituent is pyrite and that organic matter and carbonate were also altered by weathering due to this process of weathering the bulk composition of organic matter especially the molecular composition of soluble organic matter and the fluorescence colour of organic particles are changed estimates of weathering rates reveal that the annual release of sulphur and organic carbon from black shales may significantly add to anthropogenic pollution

critical considerations when assessing hydrocarbon plays using rock eval pyrolysis and organic petrology data data quality revisited abstract the dramatic increase in exploration for unconventional hydrocarbon resources has inherently fuelled the need for new source rock geochemical data the need for new data comes along with an increasing number of new users many of whom do not possess the background to interpret accurately and evaluate the quality of data sets generated by different geochemical screening techniques e g rock eval pyrolysis vitrinite reflectance here datasets from rock eval pyrolysis vitrinite reflectance and leco toc analyses are scrutinized and compared to show how failing to recognize good vs bad datasets can dramatically change interpretations during prospect or play appraisals detector saturation contamination of the sample with drilling fluid and suppression of both tmax and vitrinite reflectance are examples of complications that could compromise the validity of the results and the play or prospect reviews derived from them in addition misconceptions such as leco toc is better than rock eval 6 toc expressed by many users are a consequence of the lack of understanding of how different screening techniques and instrumentation work a solid understanding of these pitfalls and limitations can provide inexperienced geoscientists and engineers with the required support to improve risk maps for hydrocarbon charge analysis and source rock evaluations when using classic guidelines for interpreting results

formation of pretulite scpo4 by recrystallization of sc rich precursors in dolni bory pegmatite evidence for different mobility of sc y ree and zr in hydrothermal conditions three distinct types a b and c of secondary pretulite scpo4 were found in a single andalusite diaspore nodule from the quartz core of the pegmatite dyke no 3 dolni bory czech republic primary crystallization of the nodule containing pretulite precursors sc y u p rich zircon and sc w rich ixiolite proceeded at t 410 degrees c and p 2 kbar subsequent subsolidus hydrothermal alteration at t approximate to 350 300 degrees c transformed part of the andalusite to pyrophyllite and triggered complete dissolution of sc y u p rich zircon i in situ reprecipitation produced y u depleted zircon ii with common inclusions of xenotime ii and pretulite a 0 88 0 92 apfu sc 0 04 0 07 apfu zr 0 03 apfuy during the same process recrystallization of sc w rich ixiolite produced heterogeneous pretulite b 0 21 0 89 apfu sc 0 09 0 78 apfu zr 0 07 apfu y the origin of pretulite c almost ideal scpo4 closely associated with pyrophyllite replacing andalusite and distant from the potential sc precursors is explained by the separation of sc from other hfse present in the original precursors which were immobile probably due to absence of suitable strong ligands in the fluids saturation of any sc dominant mineral except thortveitite sc2si2o7 is almost never achieved during primary magmatic crystallization due to the extremely high compatibility of sc consequently the processes of hydrothermal alteration of sc enriched precursors and the selective mobilization and fractionation of sc from other hfse are important for the formation of scandium minerals c 2016 elsevier b v all rights reserved

titanium zirconium resources and production a state of the art literature review abstract recent zircon supply disruptions and the increasing demand for tio2 in pigments has focused attention on the adequacy of known and anticipated resources and the ability of current suppliers to meet future demand additionally there is now a greater focus on the environmental impact of sulfate and chloride route pigment production especially in china these methods require different types of titanium feedstocks each having different levels of availability despite investigation by various government groups consultants and scholars there remain significant discrepancies in both production and resource assessments the few publically available studies do not take into account these complexities here we review the public sources for information on zirconium and titanium production and resources using australia as a case study factors affecting resource availability the complexity of titanium and zirconium feedstocks their suitability for end uses their commercial properties supply drivers we also provide a thorough history of the titanium and zirconium industry an overview of deposit geology ilmenite alteration terminology logistics mining and processing techniques as well as an examination of each of the major co products of titanium and zirconium extraction

rare earth deposits of the murmansk region russia a review this paper reviews the available information on the geology mineralogy and resources of the significant rare earth element ree deposits and occurrences in the murmansk region northwest russia the region has one of the largest endowments of ree in the world primarily the light ree lree however most of the deposits are of potential economic interest for the ree only as by products of other mining activity because of the relatively low ree grade the measured and indicated ree2o3 resources of all deposits in the region total 22 4 and 36 2 million tonnes respectively the most important resources occur in 1 the currently mined khibiny titanite apatite deposits and 2 the lovozero loparite eudialyte deposit the kovdor baddeleyite apatite magnetite deposit is a potentially important resource of scandium these deposits all have polymetallic ores i e ree would be a by product of p ti and al mining at khibiny fe zr ta and nb mining at lovozero and fe and ti mining at afrikanda the keivy block has potential for heavy ree exploitation in the peralkaline granite hosted yumperuaiv and large pedestal zr ree deposits and the nepheline syenite hosted sakharyok zr ree deposit with the exception of the afrikanda perovskite magnetite deposit lree in perovskite and the kovdor baddeleyite apatite magnetite deposit scandium in baddelyite carbonatite bearing complexes of the murmansk region appear to have limited potential for ree by products the sound transport energy and mining infrastructure of the region are important factors that will help ensure future production of the ree

reflectance measurements of zooclasts and solid bitumen in lower paleozoic shales southern scandinavia correlation to vitrinite reflectance abstract reflectance measurements have been carried out on zooclasts graptolites chitinozoans and vase shaped microfossils and other organic particles vitrinite like particles porous granular vitrinite like particles and solid bitumen in middle cambrian to upper silurian shales from central and southern sweden and the danish island of bornholm baltic sea the most abundant organic components in all the shales are fragments of graptolites and vitrinite like particles the reflectance distribution of these two types of components is largely identical and it is suggested that the vitrinite like particles are fragments of graptolites without any recognizable morphology reflectance measurements of graptolites and vitrinite like particles yield well defined reflectance populations in samples with average r graptolite and average r vitrinite like of 0 75 r o the reflectance distributions are bimodal because of increasing bireflectance and the average reflectance value of the well defined lower reflecting population is arbitrarily used as maturity indicator our results suggest that with increasing thermal maturity the reflectance of graptolites increases faster than the predicted vitrinite reflectance the relationship between graptolite reflectance and equivalent vitrinite reflectance can be expressed by the equation vr eqv 0 73 r graptolite vitrinite like low 0 16 the gas generation window which normally is considered to begin at a vitrinite reflectance of 1 3 r o in post lower paleozoic rocks containing vitrinite starts accordingly at 1 56 r o graptolite reflectance porous granular vitrinite like particles occur in minor amounts and they may represent graptolite fragments with a non smooth surface they generally yield slightly higher reflectance than non granular vitrinite like particles and graptolite fragments the middle cambrian to furongian upper cambrian shales may contain sparse fragments of vase shaped microfossils vsm that seem to follow the maturation trend of chitinozoans in the present sample set the reflectance of chitinozoans and vsm is comparable to that of graptolites at the same level of maturity reflectance measurements of solid bitumen are a poor maturity indicator probably because bitumen can have various origins and morphologies and it may not be indigenous to the host rock

a new and prospective resource for scandium evidence from the geochemistry of deep sea sediment in the western north pacific ocean abstract scandium is a critical element in state of the art green technologies however it is also extremely expensive due to its scarcity recently some deep sea sediments that contain significant amounts of rare earth elements that are indispensable to modern industries have been discovered in the western north pacific ocean and the concentration of sc in these sediments is comparable with that of land based mines a simple leaching experiment has demonstrated that up to 70 of sc in these sediments contained within biogenic calcium phosphate particles can be recovered in 5 min using dilute acids on the basis of available core samples we propose that a promising target area to mine sc is along a west east transect between longitudes 153 30 e and 154 00 e at an approximate latitude of 21 58 n depending on the depth of the most enriched sediment layer just 1 km2 of the sediment could potentially yield 3 3 6 6 times the current global annual consumption of sc because these sediments contain an unusually high concentration at commercial quantities of industrially important heavy rare earth elements apart from sc they could be a productive source for the long term extraction of these critical metals

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

3d mineralogical mapping of the kovdor phoscorite carbonatite complex russia the kovdor baddeleyite apatite magnetite deposit in the kovdor phoscorite carbonatite pipe is situated in the western part of the zoned alkali ultrabasic kovdor intrusion nw part of the fennoscandinavian shield murmansk region russia we describe major intrusive and metasomatic rocks of the pipe and its surroundings using a new classification of phoscorite carbonatite series rocks consistent with the iugs recommendation the gradual zonation of the pipe corresponds to the sequence of mineral crystallization forsterite hydroxylapatite magnetite calcite crystal morphology grain size characteristic inclusions and composition of the rock forming and accessory minerals display the same spatial zonation pattern as do the three minerals of economic interest i e magnetite hydroxylapatite and baddeleyite the content of sr rare earth elements rees and ba in hydroxylapatite tends to increase gradually at the expense of si fe and mg from early apatite forsterite phoscorite margins of the pipe through carbonate free magnetite rich phoscorite to carbonate rich phoscorite and phoscorite related carbonatite inner part magnetite displays a trend of increasing v and ca and decreasing ti mn si cr sc and zn from the margins to the central part of the pipe its grain size initially increases from the wall rocks to the inner part and then decreases towards the central part characteristic inclusions in magnetite are geikielite within the marginal zone of the phoscorite carbonatite pipe spinel within the intermediate zone and ilmenite within the inner zone the zoning pattern seems to have formed due to both cooling and rapid degassing pressure drop of a fluid rich magmatic column and subsequent pneumatolytic and hydrothermal processes

geochemical study on a well in the western canada basin relation of the aromatic distribution pattern to maturity of organic matter abstract thirty one rock samples from a western canada basin well have been analysed for aromatics using glass capillary gas chromatography with simultaneous flame ionization and sulfur selective flame photometric detection a uniform aromatic distribution pattern with a marked predominance of di and tricyclic aromatic hydrocarbons was observed throughout a depth interval of 3000 meters comprising cretaceous and jurassic sediments the very high relative abundance of sulfur aromatics at two narrow intervals in the triassic and mississippian is attributed to a major change in facies gradual changes with increasing depth have been observed for a series of compound ratios which had been calculated from the isomers of methyl and dimethylphenanthrene and their parent compounds these changes reflect the increasing thermal maturation of the sedimentary organic matter a methylphenanthrene index mpi has been introduced which exhibited a very good correlation with vitrinite reflectance data the mpi is the first maturity parameter which is based on a series of aromatic hydrocarbons this hydrocarbon internal maturity parameter permits the recognition and definition of maturity levels in extracts which can be compared to the maturity e g vitrinite reflectance of source rocks

the ratios of dibenzothiophene to phenanthrene and pristane to phytane as indicators of depositional environment and lithology of petroleum source rocks abstract the ratio of dibenzothiophene to phenanthrene and the ratio of pristane to phytane when coupled together provide a novel and convenient way to infer crude oil source rock depositional environments and lithologies such knowledge can significantly assist in identifying the source formation s in a basin thereby providing valuable guidance for further exploration the ability to infer this information from analysis of a crude oil is especially valuable as frequently the earliest samples in a new area may be shows and or drill stem test samples from exploratory wells which are characteristically drilled on structural highs stratigraphically remote from the source formation s a cross plot of dibenzothiophene phenanthrene versus the pristane phytane ratios measured on seventy five crude oils from forty one known source rocks ranging in age from ordovician to miocene consistently classified the oils into the following environment lithology groups marine carbonate marine carbonate mixed and lacustrine sulfate rich lacustrine sulfate poor marine and lacustrine shale and fluvial deltaic carbonaceous shale and coal the dibenzothiophene phenanthrene ratio alone is an excellent indicator of source rock lithology with carbonates having ratios 1 and shales having ratios the dibenzothiophene to phenanthrene and the pristane to phytane ratios can also be used to classify source rock paleodepositional environments the classification scheme is based on the premise that these ratios reflect the different eh ph regimes resulting from the significant microbiological and chemical processes occurring during deposition and early diagenesis of sediments the dibenzothiophene phenanthrene ratio assesses the availability of reduced sulfur for incorporation into organic matter and the pristane phytane ratio assesses the redox conditions within the depositional environment interpretation of these ratios has been aided by quantitative biomarker analysis and by carbon isotope data for pristane and phytane obtained by gas chromatography isotope ratio mass spectrometry

correlations among the reflectances of vitrinite chitinozoans graptolites and scolecodonts abstract paleozoic marine sequences sampled in outcrops and wells of northeastern gaspe peninsula quebec appalachians yield kerogen composed in part of vitrinite and zooclasts chitinozoans scolecodonts and graptolites on which reflectance measurements were made the comparison between means of random measurements show that reflectance of chitinozoans is similar to that of telinite vitrinite with a cellular texture and that the reflectance of scolecodonts is significantly lower than that of telinite in the lower range of studied values at higher reflectivities differences decrease but at the end of the condensate gas zone reflectancea are not yet identical as shown by previous studies reflectance of graptolites is slightly less than that of telinite pyrobitumen reflectance is related to the lithology of the host rock and no generalized correlation can be established between the reflectance of pyrobitumen and that of vitrinite

application of organic petrography in north american shale petroleum systems a review abstract organic petrography via incident light microscopy has broad application to shale petroleum systems including delineation of thermal maturity windows and determination of organo facies incident light microscopy allows practitioners the ability to identify various types of organic components and demonstrates that solid bitumen is the dominant organic matter occurring in shale plays of peak oil and gas window thermal maturity whereas oil prone type i ii kerogens have converted to hydrocarbons and are not present high magnification sem observation of an interconnected organic porosity occurring in the solid bitumen of thermally mature shale reservoirs has enabled major advances in our understanding of hydrocarbon migration and storage in shale but suffers from inability to confirm the type of organic matter present herein we review organic petrography applications in the north american shale plays through discussion of incident light photographic examples in the first part of the manuscript we provide basic practical information on the measurement of organic reflectance and outline fluorescence microscopy and other petrographic approaches to the determination of thermal maturity in the second half of the paper we discuss applications of organic petrography and sem in all of the major shale petroleum systems in north america including tight oil plays such as the bakken eagle ford and niobrara and shale gas and condensate plays including the barnett duvernay haynesville bossier marcellus utica and woodford among others our review suggests systematic research employing correlative high resolution imaging techniques and in situ geochemical probing is needed to better document hydrocarbon storage migration and wettability properties of solid bitumen at the pressure and temperature conditions of shale reservoirs

radiocarbon evidence for decomposition of aged organic matter in the vadose zone as the main source of speleothem carbon 2015 elsevier ltd several recent studies have used records of the radiocarbon 14c bomb peak in speleothems to inversely model the soil a 14co 2 and the age distribution of soil organic material som above caves in part to investigate the potential of speleothems as sensitive records of past som dynamics the results of these modeling studies have suggested that soil co 2 at karst sites is derived primarily from the decomposition of som with turnover times on the order of decades to centuries this result is in stark contrast with observations of soil a 14co 2 at non karst sites which indicate that soil co 2 is derived primarily from root respiration and decomposition of som with much shorter turnover times this discrepancy suggests that som in karst settings may have a very different age distribution than sites that have been studied previously and or that soil co 2 is not the main source of speleothem carbon to help resolve this discrepancy we present an improved inverse model which we use to estimate the age of co 2 above several caves we also present results from a detailed case study of soil carbon dynamics at heshang cave china this work demonstrates that som in karst sites may be much older than som in non karst soils that have been studied previously but that co 2 produced in the shallow soil zone is unlikely to be the main source of speleothem carbon a review of the literature suggests that the most likely explanation for the aforementioned discrepancy is that decomposition of down washed som in the vadose zone is the dominant source of speleothem carbon

mississippian barnett shale fort worth basin north central texas gas shale play with multi trillion cubic foot potential the mississippian barnett shale serves as source seal and reservoir to a world class unconventional natural gas accumulation in the fort worth basin of north central texas the formation is a lithologically complex interval of low permeability that requires artificial stimulation to produce at present production is mainly confined to a limited portion of the northern basin where the barnett shale is relatively thick 300 ft 92 m organic rich presentday total organic carbon 3 0 thermally mature vitrinite reflectance 1 1 and enclosed by dense limestone units able to contain induced fractures the most actively drilled area is newark east field currently the largest gas field in texas newark east is 400 mi 2 1036 km 2 in extent with more than 2340 producing wells and about 2 7 tcf of booked gas reserves cumulative gas production from barnett shale wells through 2003 was about 0 8 tcf wells in newark east field typically produce from depths of 7500 ft 2285 m at rates ranging from 0 5 to more than 4 mmcf day estimated ultimate recoveries per well range from 0 75 to as high as 7 0 bcf efforts to extend the current barnett play beyond the field limits have encountered several challenges including westward and northward increases in oil saturation and the absence of lithologic barriers to induced fracture growth patterns of oil and gas occurrence in the barnett in conjunction with maturation and burial history data indicate a complex multiphased thermal evolution with episodic expulsion of hydrocarbons and secondary cracking of primary oils to gas

effects of weathering on biological marker and aromatic hydrocarbon composition of organic matter in phosphoria shale outcrop gc ms analyses were performed on core samples collected from a shale outcrop of the permian phosphoria formation in utah u s a to study effects of weathering on selected biological marker and aromatic phenanthrene hydrocarbon compounds among the biological markers the most important weathering effects are a decrease in 20s 20r diastereomer ratio of the c sub 29 steranes and loss of low molecular weight triaromatic steroids a decrease in the c sub 19 through c sub 22 tricylcic terpanes occurs relative to the total c sub 19 c sub 26 tricyclic fraction pronounced loss of methyl substituted phenanthrenes occurs relative to phenanthrene no major effect on the overall distribution of pentacyclic terpanes is evident

sensitivity of biomarker properties to depositional environment and or source input in the lower toarcian of sw germany abstract a sequence of lower toarcian sediments which are highly contrasting in their depositional environment over a 5 m depth interval has been investigated in detail for the variability of geochemical properties which are used for source characterization and oil to source correlation lower liassic marls are representative of a well aerated shallow water environment in contrast to the immediately overlying bituminous shales which are deposited under extremely reducing conditions various properties have been found to vary considerably within these two units amongst the most important are carbon isotopic composition of the kerogen the pristane phytane ratios nickel as opposed to vanadyl porphyrins and the c27 dia regular steranes although maturation within the profile does not change some of the maturation dependent biomarker properties such as the monoaromatic steroid side chain cracking and the tm ts ratio exhibit large changes which can be assigned to diagenetic processes another maturation dependent property the 20s 20r epimerization of c29 steranes exhibits smaller changes which could also be due to early diagenetic processes the study suggests that reducing and oxidizing conditions i e eh and ph in the sediment exert an influence on several biomarker precursor product pathways in maturation studies initial variations due to depositional conditions have therefore to be taken into account

algal bloom episodes and the formation of bituminite and micrinite in hydrocarbon source rocks evidence from the devonian and mississippian northern williston basin canada organic petrology incident light microscopy of middle devonian inter reef laminates and devonian mississippian epicontinental black shales williston basin canada indicates that algal bloom episodes and consequential bacterial activity played a significant role in the accumulation of amorphous bituminite iii rich organic microfacies corpohuminite like algal akinete cells produced by filamentous algae during algal bloom periods are persistent maceral inclusions within the potential hydrocarbon source rock intervals these cells ro mean range 0 24 0 90 are regarded as positive indicators of stressful palaeoenvironmental conditions unicellular tasmanites and leiosphaeridia marine alginite and variably degraded alginite remnants ghosts within the amorphous kerogen may be products of cell lysis photo oxidation and microbial alteration these processes are characteristic of algal bloom periods minute ca 1 m spheroidal and coccoidal bacteria like macerals are dispersed throughout the bituminite iii network attesting to the importance of microbial activity within the water column and sediment during and after organic matter accumulation dispersed granules laminations and replacement textures of micrinite like macerals within bituminite iii are interpreted as remnants of microbial alteration rather than a residual product of thermal maturation and hydrocarbon generation

organic rich marcellus shale lithofacies modeling and distribution pattern analysis in the appalachian basin the marcellus shale is considered to be the largest unconventional shale gas resource in the united states two critical factors for unconventional shale reservoirs are the response of a unit to hydraulic fracture stimulation and gas content the fracture attributes reflect the geomechanical properties of the rocks which are partly related to rock mineralogy the natural gas content of a shale reservoir rock is strongly linked to organic matter content measured by total organic carbon toc a mudstone lithofacies is a vertically and laterally continuous zone with similar mineral composition rock geomechanical properties and toc content core log and seismic data were used to build a three dimensional 3 d mudrock lithofacies model from core to wells and finally to regional scale an artificial neural network was used for lithofacies prediction eight petrophysical parameters derived from conventional logs were determined as critical inputs advanced logs such as pulsed neutron spectroscopy with log determined mineral composition and toc data were used to improve and confirm the quantitative relationship between conventional logs and lithofacies sequential indicator simulation performed well for 3 d modeling of marcellus shale lithofacies the interplay of dilution by terrigenous detritus organic matter productivity and organic matter preservation and decomposition affected the distribution of marcellus shale lithofacies distribution which may be attributed to water depth and the distance to shoreline the trend of normalized average gas production rate from horizontal wells supported our approach to modeling marcellus shale lithofacies the proposed 3 d modeling approach may be helpful for optimizing the design of horizontal well trajectories and hydraulic fracture stimulation strategies

diachronous variscan tectonothermal activity in the nw iberian massif evidence from 40ar 39ar dating of regional fabrics abstract multigrain concentrates of hornblende and muscovite together with whole rock slate phyllite samples have been dated 27 analyses using 40ar 39ar incremental release methods along a systematic traverse across the various lithotectonic structural elements which comprise northwestern sectors of the variscan iberian massif hornblende concentrates from amphibolites in the allochthonous ordenes complex yield plateau isotope correlation ages of 425 ma and 377 ma muscovite concentrates and whole rock slate phyllite from this and the cabo ortegal complex yield plateau ages which range from 367 ma to 295 ma analyses of similar material from the relative autochthon yield plateau ages between 359 ma and 275 ma muscovite concentrates from three late to post kinematic granitic stocks yield plateau ages between 309 ma and 274 ma at least seven of the 40ar 39ar analyses from metamorphic rocks record variable thermal rejuvenation of intracrystalline argon systems associated with emplacement of proximal granitic stocks the remaining analyses may be used to constrain the local age of various variscan tectonothermal events the oldest fabric ages are recorded in allochthonous units whereas the youngest fabric ages occur along the boundary between internal and external zones middle devonian ages are recorded in the allochthon and suggest a chronological continuity with deformational events in the relative autochthon where variscan deformation initiated in the upper devonian and diachronously prograded eastward the first deformational events recorded in the limit within the internal and external zones occured ca 20 25 ma later lower namurian variscan deformation systematically prograded diachronously eastward across the orogen as new crustal material was added along the front of the developing orogenic wedge however the entire orogen remained tectonically active with different structural features forming at different times and at different places an average propagation rate of ca 5 km m y is suggested by consideration of a 20 25 ma difference in correlative fabric ages and present separations

economic minerals of the kovdor baddeleyite apatite magnetite deposit russia mineralogy spatial distribution and ore processing optimization abstract the comprehensive petrographical petrochemical and mineralogical study of the kovdor magnetite apatite baddeleyite deposit in the phoscorite carbonatite complex murmansk region russia revealed a spatial distribution of grain size and chemical composition of three economically extractable minerals magnetite apatite and baddeleyite showing that zonal distribution of mineral properties mimics both concentric and vertical zonation of the carbonatite phoscorite pipe the marginal zone of the pipe consists of apatite forsterite phoscorite carrying fine grains of ti mn si rich magnetite with ilmenite exsolution lamellae fine grains of fe mg rich apatite and finest grains of baddeleyite enriched in mg fe si and mn the intermediate zone accommodates carbonate free magnetite rich phoscorites that carry medium to coarse grains of mg al rich magnetite with exsolution inclusions of spinel medium grained pure apatite and baddeleyite the axial zone hosts carbonate rich phoscorites and phoscorite related carbonatites bearing medium grained ti v ca rich magnetite with exsolution inclusions of geikielite ilmenite fine grains of ba sr ln rich apatite and comparatively large grains of baddeleyite enriched in hf ta nb and sc the collected data enable us to predict such important mineralogical characteristics of the multicomponent ore as chemical composition and grain size of economic and associated minerals presence of contaminating inclusions etc we have identified potential areas of maximum concentration of such by products as scandium niobium and hafnium in baddeleyite and rees in apatite

organic petrology and organic geochemistry of devonian black shales in southwestern ontario canada abstract the hydrocarbon source rock potential of the devonian marcellus and kettle point black shales in southern ontario has been assessed using rock eval pyrolysis gas chromatography gas chromatography mass spectrometry and incident light microscopy both formations contain sufficient hydrogen rich organic matter type ii to be considered possible source rocks the kerogen is predominantly marine in origin this organic matter was deposited in a clastic algal dominated environment and mainly consists of unstructured bituminite and unicellular alginite the organic microfacies indicate shelf paleodepositional settings with a transition to an open basinal region the optical reflectance fluorescence and geochemical rock eval tmax extract yields distributions of steranes and terpanes maturity data indicate that the organic matter in the kettle point formation is immature whereas in the marcellus formation it has reached the early stages of hydrocarbon generation and expulsion some devonian oils occurring in this area have characteristics similar to the marcellus extracts suggesting that more mature equivalent units from the appalchian basin could be their source

production and preservation of organic matter during deposition of the bakken formation late devonian and early mississippian williston basin abstract the organic rich up to 35 toc lower and upper black mudstone members of the bakken formation late devonian and early mississippian accumulated in response to both increased productivity and enhanced preservation that resulted from unique palaeogeographic palaeoceanographic and palaeoclimatic conditions during bakken deposition the semi isolated williston basin was located close to the equator 5 to 10 n in a zone of prevailing east to west winds a pattern of estuarine like marine circulation between the williston basin and open ocean conditions at the western craton edge of north america is proposed surface water discharged from the basin was replaced by nutrient rich deeper water sourced from the equatorial undercurrent in the pacific basin undercurrent flow into the williston basin upwelled providing a potentially sustainable source of nutrients to enhance productivity in the surface photic zone during black mudstone deposition in response to increased productivity that led to a high rate of organic sedimentation and quiescent deep water conditions due primarily to the geographic isolation of the basin and the restriction of estuarine like circulation to the upper water column anoxic bottom water developed on the basin floor as sea level rose during lower and upper black mudstone deposition anoxic bottom water expanded across the basin enhancing organic matter preservation conditions in the williston basin demonstrate that both increased productivity and improved preservation can be essential and complementary factors affecting organic rich mud deposition these results have potentially important implications for the accumulation of similarly organic rich deposits across the north american interior during late devonian and early mississippian time

solid bitumen bituminite and thermal maturity of the upper jurassic lower cretaceous chia gara formation kirkuk oil field zagros fold belt kurdistan iraq abstract the upper jurassic lower cretaceous chia gara formation a proven marine source rock characterised by predominance of amorphous organic matter aom is known from few outcrops in ne iraq and a number of exploration wells in the zagros fold belt this study presents comprehensive organic petrographic and mineralogical investigations of the dispersed organic matter and rock forming minerals of the tithonian berriasian chia gara formation intersected by the kirkuk well k 109 drilled in the giant kirkuk oil field ne iraq the organic petrographic analyses including incident light microscopy and confocal laser scanning microscopy clsm were applied to carbonate source rocks with low to moderate organic carbon contents our data demonstrate the predominance of bituminite and solid bitumen among the examined dispersed organic matter followed by oil exudates and oil globule inclusions as well as the presence of minor contributions of alginite i e tasmanites and leiospheridia liptodetrinite and vitrinite based on optical characteristics and clsm spectral fluorescence measurements examinations of bituminite point towards the presence of bituminite type iii the bituminite type iii encloses dark orange fluorescent amorphous components suggesting a genetic relationship either with liptodetrinite and or with solid bitumen the qualitative assessment of solid bitumen reveals several dissimilar forms identified in the analysed samples the photometric and spectral fluorescence measurements point to distinct reflectance values ranging between 0 19 and 0 43 sbrr and lambda max values extending from 515 nm to 590 nm respectively the corresponding results of the solid bitumen exhibit 1 a lack of a relationship with depth and 2 suggest its poor property as a reliable maturity indicator for the examined samples the presence of oil exudates oil globule inclusions and their association with solid bitumen suggests a genetic relation with the examined residues of liquid hydrocarbon phase the performed thermal maturities assessments of dispersed organic matter point towards early mature to peak mature oil window with vitrinite reflectance values ranging between 0 52 vrr at 2801 m to 0 83 vrr at 3089 m depth mineralogical analyses revealed the predominance of calcite over dolomite in the examined limestone to marl lithofacies e g clear rimmed dolomite with localised intensive dolomitisation in the phyllosilicate rich matrix predominance of calcite and siderite is observed followed by zinc blende and pyrite the composition of organic matter in the examined chia gara formation with predominance of bituminite and solid bitumen makes the major marine source rock of iraq s cretaceous petroleum systems distinctive in terms of hydrocarbon generation and migration at an oil window stage as it provides suitable explanations for its generally low hydrogen index hi with only minor terrestrial input in addition the results presented herein can be helpful for future evaluation of thermal maturities and characterisation of optical appearances of dispersed organic matter in carbonates by incident light microscopy and especially by clsm during hydrocarbon prospecting

controls on dissolved inorganic carbon and δ13c in cave waters from desoto caverns implications for speleothem δ13c assessments abstract unraveling the factors controlling the carbon chemistry and transport of carbon within extant karst systems has important implications concerning the assessment of time series 13c records of speleothems here we report the results of a 3 year study of total dissolved inorganic carbon dic and 13cdic from cave waters at desoto caverns southeastern usa that offer valuable insight on carbon transport and the accompanied isotope fractionations from end member sources to speleothems dic and 13cdic values of cave waters range from 0 2 to 6 0 mm and 2 7 to 12 9 vpdb respectively dic and 13cdic of seasonal drips show seasonal albeit noisy variability and are inversely related 13cdic 2 49 dic 0 64 r2 0 84 a shallow pool fed by multiple drips shows a bimodal 13cdic distribution with an isotopically heavier mode during winter 4 to 5 vpdb relative to summer months 9 to 10 vpdb a multi year trend of decreasing water availability during the study period is not reflected in a response of cave water carbon chemistry suggesting that rainfall amount may not be a significant controlling factor of the carbon chemistry coupled cave air winter ventilation summer stagnation and varying co2 fluxes through the soil horizon and epikarst exert the strongest influence on seasonal dic and 13cdic variability measured values of high dic and low 13cdic from cave waters collected during the summer early fall closely approximate isotopic equilibrium conditions conversely low dic and high 13cdic values during winter early months indicate kinetically enhanced isotopic fractionations within the cave waters the kinetically enhanced isotopic fractionation of hco 3 partitioned between degassed co2 and precipitated caco3 1000 ln co 2 hco 3 caco 3 ar hco 3 2 is greater by about a factor of two 6 7 0 3 relative to the same isotopic fractionation under equilibrium conditions 3 1 on the basis of 14c mass balance and paired 14c u th measurements we estimate that on average about 23 of c delivered annually by the drips to the aragonite stalagmites is derived from 14c dead dolomite cap while the remainder of 77 is derived from 14c live biomass 13c measurements of aragonite n 12 sampled from the tips of active speleothems during the summer months are consistent with theoretical aragonite 13c values calculated using the shallow pool summer early fall data thus confirming the 13c seasonality in both drips and coeval aragonite 13c values of an active stalagmite section spanning the last 200 years show a normal distribution with a mean of 7 1 1 2 n 81 and a mode of 7 to 8 that are statistically indistinguishable from the annual mean and mode of all dripwaters thus secular time series 13c records of stalagmites at desoto caverns with resolving power 10 1 year will likely carry the imprints of drip annual means that record climate driven 13c seasonal biases

alternative calibration of the methylphenanthrene index against vitrinite reflectance application to maturity measurements on oils and sediments abstract the methylphenanthrene index mpi 1 radke and welte advances in organic geochemistry 1981 pp 504 512 wiley chichester 1983 has been calibrated against vitrinite reflectance using australian carboniferous permian jurassic and tertiary sediments and coals containing terrestrial organic matter the correlation obtained was slightly different from that found previously and has resulted in an extension of the relationship to lower maturation levels vitrinite reflectance 0 5 ro in this sample set the methylphenanthrene distribution factor kvaldheim et al geochim cosmochim acta51 1883 1888 1987 showed a poorer correlation to vitrinite reflectance than mpi 1 hydrogen rich organic matter from an immature marine sequence gave anomalously high methylphenanthrene indices and confirms a source control on the index at low maturation levels the index has been used to confirm the low maturity of some australian terrestrial oils and to determine the degree of maturation of organic matter and oils in proterozoic sediments

geochemical paleoredox indicators in devonian mississippian black shales central appalachian basin usa the degree of anoxia that existed during accumulation of devonian mississippian black shales in central kentucky has been debated widely in this study geochemical data were used to elucidate paleodepositional environments for these units using analyses from ten cores collected from the outcrop belt in central kentucky sulfur carbon and selected trace element relationships were compared the sunbury shale tournasian lower mississippian and the cleveland and huron members of the ohio new albany shale fammenian upper devonian show different relationships between carbon sulfur and trace elements c s fe relationships for the sunbury suggest anoxic possibly even euxinic conditions prevailed during sediment accumulation analysis of c s fe data suggests that the cleveland may have accumulated under anoxic conditions with intermittent dysoxia whereas the huron member may have accumulated under a relatively wide range of conditions from anoxic to dysoxic to possibly oxic these three units exhibit different degrees of trace element enrichment with the approximate order of enrichment relative to an average shale being mo pb zn v ni cu cr co the sunbury shows the highest levels of enrichment followed by the cleveland with the huron showing only slight enrichment for most of these trace elements differing degrees of enrichment may reflect differences in depositional environment during accumulation high mo concentrations in the sunbury generally 200 550 ppm may infer euxinic conditions prevailed during sediment accumulation the cleveland and the huron both show considerably lower mo contents averaging around 100 ppm geochemical ratios including ni co v cr and v v ni also indicate variable paleoredox conditions for these shales based on previously established thresholds v cr and ni co ratios infer at least anoxic conditions during accumulation of the sunbury anoxic to dysoxic conditions during cleveland accumulation and dysoxic to oxic conditions for the huron v v ni ratios tend to indicate consistently lower oxygen regimes than do other paleoredox indicators and this discrepancy is greatest for the huron member it is suggested that thresholds established for paleoredox indicators in previous studies should not be applied strictly but that relative differences in these indicators collectively can infer variations in the degree of anoxia in addition relationships between corg and redox elements may help elucidate the role of anoxia in om accumulation it may be concluded from this study that the devonian mississippian black shales of central kentucky accumulated under variable bottom water conditions at least anoxic conditions prevailed during accumulation of much of the sunbury shale and the upper part of the cleveland member and possibly euxinic conditions for the sunbury bottom water conditions may have been intermittently anoxic and dysoxic during deposition of the lower cleveland during accumulation of the huron member it is likely that conditions ranged from anoxic to dysoxic to marginally oxic possibly being close to normal marine conditions at times during accumulation of the lowermost huron sediments

simulated changes in atmospheric dust in response to a heinrich stadial 1 heinrich stadials hs thought to be triggered by increased ice discharge in the high latitude north atlantic at glacial periods resulted in large freshwater forcing that weakened the atlantic meridional overturning circulation amoc these events are strongly expressed in paleoclimate records throughout the atlantic basin and much of the tropics compared to the last glacial maximum recent proxy data suggest hs were much drier and dustier in large parts of the tropics we use a global climate model coupled to a prognostic dust model to examine the response of dust to changes in climate during hs despite some significant changes in regional precipitation patterns in response to the simulated shift in the intertropical convergence zone we find that changes in winds have a larger effect on dust mobilization and deposition patterns than soil moisture or vegetation changes associated with a weaker amoc although europe was colder and drier during hs the annual mean glaciogenic dust emission rate is lower because a southward shift in the northern hemisphere jet stream leads to weaker winds and less dust mobilization the proximity of the westerly wind anomaly associated with the jet stream shift increases gustiness and dust mobilization over northwestern africa and shifts the african easterly jet southward resulting in less african dust transport and deposition over the north tropical atlantic drier conditions over the sahel region of north africa however do not lead to increased dust mobilization in our model when we perturb sahelian soil characteristics our results are in better agreement with proxies

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

paleomagnetic analysis of fold kinematics and implications for geological models of the cantabrian asturian arc north spain the ponga unit lies in the core of the cantabrian asturian arc a thrust system which was emplaced and then noncoaxially refolded during the variscan orogeny alternative models for thrust system geometry prior to refolding of the ponga unit have been proposed although the ponga unit becomes populated with steeply plunging folds under each model the alternative models imply differing kinematic histories for these folds paleomagnetic data were acquired from 22 sites in grey and red carboniferous limestones around these folds in order to determine the rotational histories of the structures and hence to identify the appropriate geological model for initial thrust system geometry low anisotropy of magnetic susceptibility indicated that the samples were suitable for rigid body rotation studies four remanence components were identified on stepwise demagnetization a very low temperature randomly orientated component v a low temperature component l present between 50 c and 200 c 64 349 95 4 4 clustered around the recent field in geographic coordinates an intermediate temperature component i present between 200 c and 400 600 c of reverse polarity and shallow inclination and showing significant between site dispersion and a high temperature component h 30 342 95 21 lying close to the eocene reference direction in geographic coordinates the i component fails a fold test based upon a first deformation phase d1 hanging wall anticline and is therefore a remagnetization the i component consistently gives positive fold tests of the steeply plunging fold structures when the structures are unfolded about their plunging hinges this demonstrates that these folds result from north south shortening of essentially homoclinal westerly dipping d1 hanging wall ramps and that alternative models involving steeply dipping interference folds arising from complex hanging wall deformation during d1 are invalid a partial restoration of the thrust system based on the former model with the paleomagnetic data pinned to a calculated stephanian reference direction shows that the thrust front was approximately north south in trend in the ponga unit as it was farther south in the esla unit where anticlockwise rotations and dextral wrench faulting have subsequently occurred the data also record a tilt to the north of up to 30 which has occurred incrementally since the end of variscan deformation

scandium of the kovdor baddeleyite apatite magnetite deposit murmansk region russia mineralogy spatial distribution and potential resource abstract despite extensive industrial application global scandium resources are uncertain although sc is mainly supplied as a by product of mining of rare earth metals uranium or aluminum it is also concentrated by carbonatite process both magmatic and post magmatic in this paper we report data on sc distribution within the kovdor baddeleyite apatite magnetite deposit phoscorite carbonatite pipe in the murmansk region of russia which seems to be a significant reservoir of this strategic metal we show that baddeleyite is the main sc concentrating mineral and reveal the spatial distribution of sc bearing baddeleyite within the kovdor phoscorite carbonatite pipe the scandium content in baddeleyite differs according to the petrographic zonation of the pipe culminating in the inner axial zone of the pipe and in dolomite carbonatites cutting the pipe we have estimated the amount of sc2o3 in the kovdor deposit as amounting to 420 t at average content in baddeleyite of 0 078 wt and revealed the economic potential for sc recovery as a by product other sc bearing minerals pyrochlore and ilmenite groups zirconolite and juonniite have been described and opportunity of sc recovery was examined too

organic matter provenance and depositional environment of marine to continental mudstones and coals in eastern ordos basin china evidence from molecular geochemistry and petrology abstract cyclothems composed of interbedded mudstone coal and sandstone layers make up the taiyuan and shanxi formations in the late carboniferous to early permian in north china under a marine to continental depositional environment the cyclothems act as important fossil energy hosts such as coalbeds hydrocarbon source rocks and unconventional natural gas reservoirs organic geochemistry and petrology of mudstones and coals in the taiyuan and shanxi formations in the eastern ordos basin were studied to reveal the organic matter sources and paleoenvironments total organic carbon toc contents vary from 1 1 wt mudstone to 72 6 wt coal the samples are mainly within the oil window with the tmax values ranging from 433 to 469 c organic petrology and source biomarkers indicate that the mudstones were sourced from a mixed organic matter input and terrigenous organic matter predominates over aquatic organic matter the coals are mostly sourced by terrigenous organic matter inputs high concentrations of hopanes argue for a strong bacterial input some m z 217 mass chromatograms have peaks at the hopanes retention times as a result of high hopane to sterane ratios these hopane derived peaks do not interfere the identification of the steranes because the hopanes and the steranes have different retention times maturity dependent biomarkers demonstrate that the samples have been thermally mature which agree with the tmax values anomalously low c29 20s 20s 20r and c29 sterane ratios are present in all the samples and are interpreted as due to the terrigenous organic matter input or the coal related depositional environment in addition biomarkers and iron sulfide morphology indicate that the organic matter of the mudstones deposited in a proximal setting with shallow brackish fresh water bodies with consideration of preservation of organic matter the redox conditions are dysoxic redox oscillations resulted in the records of oxic conditions in some samples finally the coals and the mudstones mainly generate gas and have poor oil generative potential

calculation of petroleum masses generated and expelled from source rocks abstract an algebraic scheme for calculating the masses of petroleum formed in mature source rocks has been constructed the scheme exploits routine geochemical measurements and a basic understanding of the behaviour of sedimentary organic matter at elevated temperatures under both laboratory and subsurface conditions application of these techniques to data from a wide range of source rock types has led to the following general conclusions 1 1 major oil and gas generation from kerogen occurs between 120 and 150 c in the subsurface gas generation continues to temperatures 160 c 2 2 oil prone source rocks with average initial potential 5 kgt 1 of rock and average organic carbon contents 1 5 expel 60 90 of the total oil generated 3 3 oil expulsion from leaner source rocks is less efficient most of the oil generated remains in the source rock it is subsequently converted to lighter components at higher temperatures and expelled in the vapour state 4 4 the major loss of organic carbon from rich oil prone source rocks during generation and expulsion means that the petroleum potential and organic carbon content of mature source rocks are much less than their initial immature values hence the algebraic scheme must be used to calculate the initial values before expelled petroleum masses can be determined