iron solubility driven by speciation in dust sources to the ocean particulate aerosols are thought to be the primary source of iron to the oceans but the factors determining their solubility and thus bioavailability are unclear x ray absorption analysis reveals that speciation controls the solubility of iron in three large sources of aerosol iron

mineral microspherules in chinese coal and their geological and environmental significance abstract studies of finer grained minerals in coal have great significance for both geology and the environment eleven coal samples of different rank were collected from different regions in china and mineral microspherules were identified in these samples by scanning electron microscopy with energy dispersive x ray spectroscopy sem edx the microspherules usually occur as regular spheres with smooth surfaces and have an average size of less than 5 m in diameter most microspherules are colloidal in origin and include phases such as fe sulfides glauconite fe hydr oxides calcium oxalate and allophane allophane is a product of colloidal al2o3 and sio2 which as a precursor of kaolinite exists ubiquitously in the coals as does kaolinite some microspherules such as garnet and sphene are mainly derived from detrital sources and a few microspherules probably result from volcanogenic ash and or from cosmic dust ultrafine na bearing minerals were also found in the coals such micro sub micro and ultrafine minerals in coal may play an important role in the formation of ultrafine coal fly ash particles

a comprehensive study on geometric topological and fractal characterizations of pore systems in low permeability reservoirs based on sem micp nmr and x ray ct experiments abstract characterization of pore systems in subsurface systems is of great importance for predicting the properties of rocks and classifying the subsurface systems geometric features have been used widely for this aim but topological characteristics of the pore structures are not studied much in fact accurate characteristics of pore space should comprise both its geometric and topological properties in this paper the above vital characteristics are comprehensively studied based on direct experimental results besides previous studies aiming at linking fractal dimension analysis to pore space are often based on limited sources of information which are the mercury injection capillary pressure micp and nuclear magnetic resonance nmr in this paper the scanning electron microscope sem micp nmr and x ray computed tomography x ray ct experiments are all used to characterize the geometric and topological properties of pore space of several low permeability porous media based on our observations the advantages and disadvantages of the above techniques in characterizing the pore structure are also summarized moreover the differences of these three experiments are quantified using fractal dimension the results indicate that the nmr technique is a promising tool for characterizing geometric features of pore systems as it can cover more details than other techniques most of geometric topological fractal and transport properties of pore space can be obtained from x ray ct method which is unique among all the methods in addition the 3d fractal dimensions of pore systems obtained from nmr is smaller than that from micp which is due more ultra micropores captured by nmr that smooth the surface of the pore systems finally a novel method constrained by a new pore shape factor for calculating the pore size from 2d images is proposed by which the pore size distributions are compared more effectively

the ombrina rospo plateau apulian platform evolution of a carbonate platform and its margins during the jurassic and cretaceous abstract in this paper we analyze the jurassic and cretaceous evolution of the buried northwards stretch of the apulia platform southern italy ombrina rospo plateau orp and adjacent adriatic basin exploration wells indicate that inner platform carbonate facies across the orp in the jurassic and lower cretaceous are capped along a subaerial exposure surface by oligocene miocene carbonates a nw trending intra platform basin casalbordino corridor was infilled with shallow to deeper water sediments in the late early to late cretaceous interval while platform margins were experiencing tectonic reactivation the orp to basin transitional belt formed a corner defining a nw and a ne margin the nw margin was essentially stationary a syn and early post rift platform toe bypass wedge formed when late hettangian sinemurian extension produced the platform basin relief export of platform material coupled with a halt of faulting made the platform slope profile continuous in the late early or early middle jurassic possibly across an ooidal rim late jurassic ellipsactinia coral reefs passed downdip into bioclastics the maiolica fm displays two cycles m1 m2 where m2 onlaps the slope built by m1 in the aptian with lithospheric arching a high angle fault rejuvenated the margin off this margin a narrow basin locked between the orp and a pelagic carbonate platform was largely infilled with turbidites sourced by the orp but the high hampered the dispersal of the sand fraction the ne margin displays prograding ooidal to bioclastic clinoforms middle and upper jurassic downlapping onto the rift basin in the lower cretaceous the platform recovered after a slow down of carbonate productivity m1 2 boundary the marne a fucoidi fm thickens at the toe of and seals a fault backstepping the margin further backstepping occurred 5 km platformwards along a cenomanian normal fault producing room for a rudist factory a retreating rocky shoreline sourced breccias while downdip the shallow water facies graded into the scaglia fm basin along a ramp like profile with low angle clinoforms merging with turbidites

combined sem and reflected light petrography of organic matter in the new albany shale devonian mississippian in the illinois basin a perspective on organic pore development with thermal maturation abstract organic matter hosted pores are an important aspect of pore systems in unconventional gas shale reservoirs along with thermal maturity organic maceral type critically controls the development of secondary organic matter hosted pores three new albany shale samples devonian mississippian kerogen type ii sequence having thermal maturities ranging from a vitrinite reflectance ro of 0 55 to 1 42 were analyzed using a reflected light microscope and a field emission scanning electron microscope organic pores were examined in specific organic macerals and solid bitumen at different thermal maturities vitrinite and inertinite derived from terrestrial woody materials occur as discrete particles in this black shale within the resolution limits of the scanning electron microscope these two macerals do not appear to display enhanced secondary pores associated with increases in thermal maturity cellular pores 0 2 10 m in inertinite were observed throughout the entire maturity range and were typically filled with authigenic quartz or solid bitumen because of thermal degradation amorphous organic matter was not observed at maturities greater than ro 0 80 alginite derived from tasmanites cysts matures later than amorphous organic matter and is still present at ro 0 80 however it is in the process of transforming to pre oil bitumen and shows weak orange yellow fluorescence compared to strong greenish yellow fluorescence in lower maturity samples at a maturity of ro 1 42 alginite could no longer be observed as a distinct phase because of its complete transformation to hydrocarbons and bitumen alginite began to develop secondary pores when it was in the process of transforming to pre oil bitumen which indicates that some liquid and gaseous hydrocarbons left the alginite during this part of the maturation process solid bitumen developed along the original amorphous organic matter networks and now occupies interparticle space between quartz dolomite k feldspar clay and mica grains as well as the cellular pores in inertinite particles solid bitumen becomes smaller and more porous with thermal maturation and thus becomes increasingly unidentifiable with the optical microscope solid bitumen hosted pores 20 1000 nm are the main organic pore type documented in the studied samples and they are more common in shales within the gas window than those in the oil window secondary nanopores in the solid bitumen network play a significant role in hydrocarbon storage and migration

weddellite occurrence in peats and other organic rich sediments of florida abstract the mineral weddellite calcium oxalate dihydrate is rarely reported in sediments although it is common in biologic materials including plants forest soils and the urinary stones of mammals research designed to evaluate the factors influencing the fuel grade potential of peat deposits in florida has now documented the occurrence of weddellite as a primary constituent in the inorganic ash fraction of peat and other organic rich soils weddellite is believed to originate within the peat forming basin rather than as a product of sample storage or laboratory preparations the mineral s origin is genetically related to the metabolic activity of abundant plant life at the depositional site and its concentration in the basin is directly related to the percentage of organic matter pr served in the sediments scanning electron micrographs reveal that the mineral s characteristic prismatic needle shape is preserved in peat differential thermal analysis shows initial water loss endotherms at approximately 100 c and 200 c followed by exothermic transformations to caco3 at 300 c and to cao near 780 c

isolated stationary carbonate platforms the middle triassic ladinian of the marmolada area dolomites italy as a result of a phase of extensional tectonics in the western tethyan region a horst and graben topography formed during the middle triassic ladinian in northern italy horsts were sites of shallow water carbonate sedimentation while pelagic and volcaniclastic sediments were deposited in the grabens two carbonate platforms approximately 500 m thick can be distinguished in the marmolada area of the dolomites the marmolada platform proper which covered an area of 6 km2 and the costabella platform which extended for about 12 km in a nw se direction and was about 3 km across the facies of these isolated platforms reflect the influence of storms from the sw windward platform margins were characterized by a marine sand belt of skeletal and aggregate grainstones with a dominant platform directed cross stratification the central portions of the platforms were occupied by supratidal sand cays which are made up of storm washovers leeward parts of the platforms are composed of shallow subtidal sand flat deposits laterally discontinuous reefs chiefly composed of various calcareous algae are developed at the outer margins of the platforms along windward margins reefs may form a belt several hundred metres wide along leeward margins their width is commonly reduced to some tens of metres foreslope talus breccias surround the platforms clinoform bedding showing basinward dips of 30 40 is typical of this facies belt which is approximately 2 km wide basinal sediments only some tens of metres thick are radiolarian micrites abundant sediment gravity flow deposits expand the basinal sequence at the toes of windward margins and were probably triggered by storm return flows synsedimentary faults striking both nne ssw and nw se separate the bedded platform limestones from flank deposits and reefs they account for the stationary nature of the platforms neptunian dykes show preferred nne ssw and e w trends sinistral displacements are associated with nw se trending faults depressions in the basins filled with red turbiditic pelagic sediments show n s trends and are probably compressional in origin the structural pattern may have resulted from oblique nw se oriented extension of the e w trending middle triassic graben zone of the dolomites in the ladinian of the dolomites the stationary platform type can be distinguished from a retrograding type whereas continuously prograding platforms apparently did not develop

morphological indicators of structural control relative sea level fluctuations and platform drowning on present day and miocene carbonate platforms abstract the morphology of carbonate platforms may be influenced by tectonic activity and eustatic variations 3d seismic data and satellite imagery are used in order to investigate the morphological similarities between present day carbonates platforms east of borneo island and miocene carbonate platforms of the south china sea the morphological similarities exhibit platform fragmentation that could be caused by subtle faulting sufficient to drown reef rims platform contraction which is a result of back stepping of the reef margin during a relative sea level rise and polygonal patterns in internal lagoons described as mesh reefs in modern platforms and possibly interpreted as karst in miocene platforms vertical movements may trigger the formation of new geomorphological conditions that modify the distribution of coral growth with respect to the new hydrodynamic conditions in space and time these movements uplift and tilting reduce and localize the space necessary for the coral ecosystem explaining the contraction leading to drowning of parts of and ultimately the whole platform

abundances and distribution of minerals and elements in high alumina coal fly ash from the jungar power plant inner mongolia china abstract the fly ash from the jungar power plant inner mongolia china is unique because it is highly enriched in alumina al2o3 50 the fly ash mainly consists of amorphous glass and mullite and trace amounts of corundum quartz char calcite k feldspar clay minerals and fe bearing minerals the mullite content in fly ash is as high as 37 4 because of high boehmite and kaolinite contents in feed coal corundum is a characteristic mineral formed during the combustion of boehmite rich coal samples from the economizer were sieved into six size fractions 500 mesh and separated into magnetic mullite corundum quartz mcq and glass phases for mineralogical and chemical analysis the corundum content increases but amorphous glass decreases with decreasing particle size fractions of small particle sizes are relatively high in mullite probably because mullite was formed from fine clay mineral particles under high temperature combustion condition similarly fine corundum crystals formed in the boiler from boehmite in feed coal the magnetic phase consists of hematite magnetite magnesioferrite and mgfealo4 crystals the mcq phase is composed of 89 mullite 6 1 corundum 4 5 quartz and 0 5 k feldspar overall the fly ash from the power plant is significantly enriched in al2o3 with an average of 51 9 but poor in sio2 fe2o3 cao mgo na2o p2o5 and as arsenic tio2 th al2o3 bi la ga ni and v are high in mullite and the magnetic matter is enriched in fe2o3 cao mno tio2 cs co as cd ba ni sb mgo zn and v the remaining elements are high in the glass fraction the concentration of k2o na2o p2o5 nb cr ta u w rb and ni do not clearly vary with particle size while sio2 and hg decrease and the remaining elements clearly increase with decreasing particle size

phase mineral and chemical composition of composite samples from feed coals bottom ashes and fly ashes at the soma power station turkey abstract the phase mineral and chemical composition of feed coals fcs and their bottom ashes bas and fly ashes fas produced in the soma thermo electric power station tps turkey was characterized fcs are high ash soma subbituminous coals abundant in moisture and ca and depleted in s the inorganic composition in decreasing order of significance of fcs includes calcite quartz kaolinite illite muscovite chlorite plagioclase gypsum pyrite montmorillonite k feldspar dolomite siderite ankerite opal and volcanic glass the results for 57 elements studied show that ca nb cs v li have significantly higher contents in fc ashes than the respective clarke values for coal ashes the water soluble residues isolated from fcs include gypsum calcite inorganic amorphous matter ca mg na k phase and opal these residues are enriched in na se s b mg mo sr ca k the phase mineral composition of bas and fas includes mainly glass quartz char mullite plagioclase calcite and portlandite and to a lesser extent illite muscovite melilite hematite anhydrite lime cristobalite kaolinite and magnetite minor amounts of k feldspar dolomite ankerite fe spinel gypsum and ca k na phase also occur in bas and fas fas are enriched in inorganic matter glass cristobalite mullite fe oxides lime and anhydrite and depleted in mineral matter char quartz clay minerals melilite portlandite and carbonates in comparison with bas only se is significantly enriched in bas and fas compared to fc ashes most of the trace elements in particular as bi cd ge pb sn tl and w are more abundant in fas while bas are more enriched in ca cs fe ho mn p sc se and tb significant percentages 11 59 of elements initially present in fcs namely s sb sn ta mo bi zn ni na lu tm b were emitted by stack emissions and not captured by the cleaning equipment in the soma tps some genetic features properties possible environmental concerns and potential utilization directions related to fcs bas and fas are also discussed

mineralogy and geochemistry of the no 6 coal pennsylvanian in the junger coalfield ordos basin china abstract this paper discusses the mineralogy and geochemistry of the no 6 coal pennsylvanian in the junger coalfield ordos basin china the results show that the vitrinite reflectance 0 58 is lowest and the proportions of inertinite and liptinite 37 4 and 7 1 respectively in the no 6 coal of the junger coalfield are highest among all of the late paleozoic coals in the ordos basin the no 6 coal may be divided vertically into four sections based on their mineral compositions and elemental concentrations a high boehmite content mean 6 1 was identified in the no 6 coal the minerals associated with the boehmite in the coal include goyazite rutile zircon and pb bearing minerals galena clausthalite and selenio galena the boehmite is derived from weathered and oxidized bauxite in the weathered crust of the underlying benxi formation pennsylvanian a high pb bearing mineral content of samples zg6 2 and zg6 3 is likely of hydrothermal origin the no 6 coal is enriched in ga 44 8 g g se 8 2 g g sr 423 g g zr 234 g g rees 193 3 g g hg 0 35 g g pb 35 7 g g and th 17 8 g g gallium and th in the no 6 coal mainly occur in boehmite and the pb bearing selenide and sulfide minerals contribute not only to se and pb contents in the coal but also probably to hg content a high zr content is attributed to the presence of zircon and sr is related to goyazite the rees in the coal are supplied from the sediment source region and the rees leached from the adjacent partings by groundwater

trace element geochemistry of altered volcanic ash layers tonsteins in late permian coal bearing formations of eastern yunnan and western guizhou provinces china trace element compositions were determined by instrumental neutron activation analysis inaa in 30 samples of synsedimentary volcanic ash derived tonsteins and detrital claystones from coal seams within the late permian coal bearing formation of eastern yunnan and western guizhou provinces china the characteristics of trace element geochemistry in the tonsteins can be distinguished from those of detrital claystones because of the former s unique volcanic ash origin the detrital claystones are characterized by their relatively high content of v ti sc cr co and ni relatively low content of th and u th u ratio and small negative eu anomaly eu eu 0 63 0 93 overall these trace element characteristics are consistent with a mafic source similar to the composition of basalt rocks in the erosional region on the western edge of the study area in contrast the tonsteins are low in v ti sc cr co and ni contents and have a high th u ratio with a distinct negative eu anomaly eu eu normally in the range of 0 2 0 4 consistent with a silicic magmatic source within the group of tonsteins those from the lower section p2 1 of the coal bearing formation are relatively high in ti zr hf nb ta and rare earth elements ree as compared to those from the middle and upper sections p2 2 3 in trace element discrimination diagrams scatter plots of hf ta ti ta ti v hf sc lu hf and lu th tonsteins from the p2 1 horizon always fall in isolated distribution areas separate from the tonsteins of the p2 2 3 horizon these results suggest that the source materials of tonsteins from the two separate horizons were probably derived from volcanic ash falls of two distinctly different natures based on a comparison of the concentrations and assemblages of trace elements between various magmatic rocks the source materials of tonsteins from p2 1 horizon were mostly composed of calc alkalic silica poor volcanic ash similar to rhyodacitic magma whereas those from p2 2 3 were apparently more siliceous and k rich rhyolitic magma thus tonsteins from the two different horizons are characterized by unique geochemical properties which remain constant over a wide lateral extent integration of trace elemental compositions with mineralogical and textural observations makes possible the establishment of tonstein stratigraphy thus facilitating more precise and reliable coal seam correlations

a preliminary study of mineralogy and geochemistry of four coal samples from northern iran abstract this study is related to four jurassic age bituminous coal 0 69 1 02 ro samples collected from coal mines from the west central and east of central alborz in northern iran geological settings played key roles in determining the geochemistry and mineralogy of coals from the central alborz region of northern iran the mineralogy of coals from the eastern part of the region is dominated by kaolinite halloysite and carbonates such as calcite dolomite ankerite and siderite the coals were deposited in a lacustrine environment in the western part of the region where the depositional setting was also lacustrine with volcanic input and tonstein deposition glass shards present the coal primarily contains kaolinite 68 and fluorapatite 26 in contrast coal from the central part of the region which was deposited in a terrestrial environment and on eroded limestone and dolomite rocks is dominated by dolomite 98 with little input by kaolinite these coals have low sulphur 0 35 0 70 wt which is mostly in the organic form 0 34 0 69 wt pyritic sulphur is detected only in one coal and in small quantities the boron contents of these coals range from 9 to 33 mg kg indicating that deposition occurred in a fresh water environment coal with higher concentrations of ba sr and p contain fluorapatite and goyazite gorceixite series baal 3 po 4 2 oh 5 h 2 o minerals which indicates volcanoclastic input compared to world coal averages these coals exhibit low concentrations of elements of environmental concern such as as 1 3 5 9 mg kg cd

geological controls on coalbed methane reservoir capacity and gas content the influence of coal composition and rank on coalbed methane reservoir capacity gas content and gas saturation have been investigated for a series of australian canadian and united states coals globally there is no or little correlation between coal rank and methane adsorption capacity as commonly assumed although in particular basins there are general trends with rank and composition micropore1 capacity and surface area determined from low pressure carbon dioxide adsorption isotherms 0 c decrease and then increase with rank passing through a minimum in the high volatile bituminous coal rank there is no consistent variation in modal micropore size or size distribution with rank for suites of isorank coals there is a poor permian bulli and wongawilli seams australia to good positive correlation gates formation coal seams lower cretaceous canada between vitrinite content and methane adsorption capacity dry ash free and as received bases for each isorank coal suite there is a good correlation between micropore capacity and abundance of vitrinite and high pressure methane adsorption capacity comparison of coals of similar composition but from different isorank suites indicates however that the coals with the highest methane adsorption capacity do not necessarily have the highest micropore capacity such results are counterintuitive most pore volume available for methane adsorption is generally assumed to be microporosity it is suspected that moisture prevents methane from accessing some microporosity or competes with methane for adsorption space carbon dioxide micropore capacity which is performed on a dry basis may thus not reflect the microporosity available for gas adsorption in moisture equilibrated coals alternatively because of differing physical and chemical properties of carbon dioxide and methane apparent microporosity available to carbon dioxide due to greater energy of adsorption may not be available to methane total desorbed gas from canister analyses of sydney basin australian coals suggests that most coals are under saturated for a small data set the degree of saturation is negatively correlated with permeability r 0 78 suggesting preferential gas leakage from the higher permeability coals which are vitrite rich some degree of under saturation is probably the result of increased reservoir capacity as a consequence of uplift of the coal seams and thus lower temperatures following gas generation rates of desorption are correlated with total gas content r 0 79 but do not correlate with rank or any compositional parameter

mechanism of shale gas occurrence insights from comparative study on pore structures of marine and lacustrine shales abstract the exploration practices of marine and lacustrine shale gas in the upper yangtze platform south china show that there is a huge difference in gas content which is mainly related to the difference of pore structure this study is focused on marine longmaxi and lacustrine da anzhai shales in the upper yangtze platform and their pore structure characteristics were compared and the mechanism of shale gas occurrence were discussed first the pore structures of marine and lacustrine shales were characterized and the effects of organic matter abundance maturity and inorganic minerals on porosity were investigated then the contributions of different components to porosity were evaluated and the occurrence mode of methane in the pores of marine and lacustrine shales was established the results show that 1 three pore types can be observed in both marine and lacustrine shales organic matter hosted pores om pores framework minerals associated pores fm pores and clay minerals associated pores cm pores om pores are more developed in marine shale and cm pores are more developed in lacustrine shale 2 low pressure gas adsorption lpga results show that the micropores of marine shale are dominated by pores of 0 4 0 7 nm and the micropores of lacustrine shale are dominated by pores of 0 5 0 9 nm while the mesopores of marine shale are dominated by pores of 2 10 nm and the mesopores of lacustrine shale are dominated by pores of 3 30 nm which are consistent with mip results 3 organic matter has an impact on porosity of marine and continental shales but is not the most important controlling factor and the contribution of organic matter to porosity in marine shale is greater than the contribution of organic matter to porosity in lacustrine shale shale porosity increases first and then decreases with the increase of maturity which may be related to the carbonization of organic matter 4 om pores and cm pores tend to be preserved due to the presence of rigid grains that form rigid frameworks preventing these pores from collapsing fm pores are mainly related to the dissolution of framework minerals by organic acids and these dissolution pores can greatly improve the porosity and permeability of shale 5 quantification of porosity as related to mineralogy shows that om pores contribute approximately 37 to total porosity of marine shale and 24 to total porosity of lacustrine shale and cm pores contribute approximately 53 to total porosity of marine shale and 67 to total porosity of lacustrine shale 6 shale gas occurrence is mainly controlled by the distribution mode of pore systems which are composed of om pores fm pores and cm pores it is due to higher percentage on om pores and lower percentage on cm pores that gas content of marine shale is generally higher than that of lacustrine shale

conservative behavior of mg isotopes in massive dolostones from diagenesis to hydrothermal reworking abstract mg isotopes in syndepositional dolomite have been suggested to be a potential proxy for understanding seawater chemistry however it is argued that the 26mg values of dolomite could be complicated by the effects of early diagenesis and later hydrothermal activities further investigations into the behaviors of mg isotopes in dolomitization systems are needed to resolve this controversy in the present study we investigated early ordovician dolostones from the tarim basin including diagenetically altered dolomites hydrothermally altered dolomites and well preserved dolostones that precipitated in the slope margin and interior of a carbonate platform different types of dolomites bulk dolostone and limestone were sampled by microdrilling for analyses of c o mg isotope compositions and ree concentrations the dolostone 13c values match those of coeval seawater and the ree distribution patterns in the dolostones are comparable with those in the limestones indicating that the dolostones originated from syndiagenetic dolomitization the 26mg values of the various syndiagenetic dolomites that formed in the slope margin and interior of the carbonate platform are similar averaging approximately 2 06 0 20 no stratigraphic variability in the dolomite mg isotopes can be discerned which implies that the mg isotope compositions of the porewater were homogeneous during massive dolomitization and remained in equilibrium with seawater additionally the 26mg values of the altered dolostone do not show correlations with diagenetic and hydrothermal signals demonstrating that dolomite mg isotopes are insensitive to postdepositional alteration given these facts we propose that mg isotopes in dolostones have conservative behaviors during diagenesis and late stage hydrothermal reworking

pore characterization of isolated organic matter from high matured gas shale reservoir abstract knowledge of pore structure of isolated organic matter om provides guidance for better understanding the origin distribution and characterization of pore system in gas shale reservoir and can be used to better comprehend the storage and transport mechanism of natural gas in shale reservoir pore structure characteristics of isolated organic matters and its corresponding bulk shales were investigated for five high matured marine shale samples from the lower silurian longmaxi formation in south china using x ray diffraction xrd total organic carbon content toc tests field emission scanning electron microscope fe sem observation and ultra low pressure nitrogen gas physisorption the results indicate that om hosted pores are abundant in bulk shale samples under fe sem observation the bet surface area and the bjh pore volume of isolated om are approximately three times greater than that of bulk shale samples pore size distribution psd of isolated om from five shale samples show a consistent variation pattern additionally with increasing toc content the psd curves of isolated om gradually grow down as result of the ductility of om bimodal psd in surface area and unimodal psd in pore volume exist in both isolated om and bulk shale samples indicating surface area is mainly associated with micropores and fine mesopores

characterization of the micropore systems in high rank coal reservoirs of the southern sichuan basin china to gain a better understanding of the characteristics of micropore systems in high rank coal reservoirs 51 coal core samples collected from 16 wells were examined by maceral analysis proximate analysis scanning electron microscopy observation low temperature nitrogen gas adsorption and nuclear magnetic resonance nmr the results show that pores in coals can be divided into plant tissue hole blowhole dissolved pore and intercrystalline pore and they have three structure shapes open pore semiclosed pore and ink bottle pore the total specific surface area brunauer emmet teller bet ranges from 0 611 to 7 to averaged at the total pore volume barrett joyner halenda model bjh ranges from 0 0018 to 0 0001 to with an average of and it shows a good positive relationship with the adsorption amount shows a good positive relationship with the total and the average pore size ranges from 5 775 to 17 842 nm pores that are smaller than 5 nm make up the main contribution to the pore surface area and those larger than 10 nm contribute greatly to the pore volume inertinite rich coals have higher total specific surface area pore volume pore size and adsorption capacity than those in vitrinite rich coals lopingian coal reservoirs are characterized by low porosity and extremely low permeability obtained from nmr tests and the permeability has a positive correlation with the porosity the average permeability of inertinite is almost twice that of vitrinite

oceanographic and eustatic control of carbonate platform evolution and sequence stratigraphy on the cretaceous valanginian campanian passive margin northern gulf of mexico an integrated sequence stratigraphic study based on outcrop core and wireline log data documents the combined impact of cretaceous eustacy and oceanic anoxic events on carbonate shelf morphology and facies distributions in the northern gulf of mexico the diverse facies and abundant data of the comanche platform serve as a nearly complete global reference section and provide a sensitive record of external processes affecting cretaceous platform development regional cross sections across the shoreline to shelf margin profile provide a detailed record of mixed carbonate siliciclastic strata for the hauterivian to lower campanian stages ca 136 to 80 ma the study window on the slowly subsiding passive margin allows the stratigraphic response to external forcing mechanisms to be isolated from regional structural processes three second order supersequences comprised of eight composite sequences are recognized in the valanginian barremian the aptian albian and the cenomanian campanian the valanginian barremian supersequence transitioned from a siliciclastic ramp to carbonate rimmed shelf and is a product of glacial ice accumulation and melting as well as variable rates of mid ocean ridge volcanism the aptian albian supersequence chronicles the drowning and recovery of the platform surrounding oceanic anoxic events 1a and 1b the cenomanian campanian supersequence similarly documents shelf drowning following oceanic anoxic event 1d after which the platform evolved to a deep subtidal system consisting of anoxic dysoxic shale and chalk in the time surrounding oceanic anoxic event 2 each period of oceanic anoxia is associated with composite sequence maximum flooding termination of carbonate shelf sedimentation and deposition of condensed shale units in distally steepened ramp profiles composite sequences unaffected by oceanic anoxic events consist of aggradational to progradational shelves with an abundance of grain dominated facies and shallow subtidal to intertidal environments because they are products of eustacy and global oceanographic processes the three supersequences and most composite sequences defined in the south texas passive margin are recognizable in other carbonate platforms and published eustatic sea level curves

variations in pore characteristics in high volatile bituminous coals implications for coal bed gas content abstract the seelyville coal member of the linton formation pennsylvanian in indiana was studied to 1 understand variations in pore characteristics within a coal seam at a single location and compare these variations with changes occurring between the same coal at different locations 2 elaborate on the influence of mineral matter and maceral composition on mesopore and micropore characteristics and 3 discuss implications of these variations for coal bed gas content the coal is high volatile bituminous rank with r 0 ranging from 0 57 to 0 60 bet specific surface areas determined by nitrogen adsorption of the coals samples studied range from 1 8 to 22 9 m 2 g bjh adsorption mesopore volumes from 0 0041 to 0 0339 cm 3 g and micropore volumes determined by carbon dioxide adsorption from 0 0315 to 0 0540 cm 3 g the coals that had the largest specific surface areas and largest mesopore volumes occur at the shallowest depths whereas the smallest values for these two parameters occur in the deepest coals micropore volumes in contrast are not depth dependent in the coal samples examined for this study mineral matter content influenced both specific surface area as well as mesopore and micropore volumes it is especially clear in the case of micropores where an increase in mineral matter content parallels the decrease of micropore volume of the coal no obvious relationships were observed between the total vitrinite content and pore characteristics but after splitting vitrinite into individual macerals we see that collotelinite influences both meso and micropore volume positively whereas collodetrinite contributes to the reduction of mesopore and micropore volumes there are large variations in gas content within a single coal at a single location because of this variability the entire thickness of the coal must be desorbed in order to determine gas content reliably and to accurately calculate the level of gas saturation

geochemical attributes pore structures and fractal characteristics of barakar shale deposits of mand raigarh basin india abstract pore structures in the shale matrix are an essential factor affecting the storage capacity of gas of shale beds as well as production performance twenty organic rich shale samples at different depths were collected from barakar formation of mand raigarh basin to examine the pore structure and their fractal characteristic fractal dimension was calculated by following fhh theory to investigate the complexity of pore surfaces storage mechanism and the pore network system the complex pore system influenced by thermal cracking of organic matter pore dissolution during geochemical weathering and tectonics of the basins having surface area 5 56 23 94 m2 g avg 14 21 m2 g whereas the pore volume determined using the bjh model varying from 0 035 to 0 076 cc g avg 0 053 cc g ftir spectrum demonstrated that significant presence of aliphatic side chains and aromatic carbon structures existing in studied shale influencing the pore volume it is summarized that pores and matrix of shale are built by complex mixtures of organic and inorganic content further the pores are categorized into organic pores evolved during thermal cracking inter granular intra granular and inter crystalline due to the large content of altered clays and minerals showing fissile nature the sem edx derived facies indicating the involvement of different chemical constituents following the trend of alteration as well as carbon enrichment the d1 and d2 values obtained through fhh model range from 1 17 to 2 45 and 2 54 2 70 the fractal values particularly d2 are 3 demonstrating the pore surfaces and structure of studied shales beds are complex and heterogeneous this study helps to enhance the exploration and advancement in the shale gas resources from ib river of mand raigarh basin india

carbonate platform margin architecture and its influence on cambrian ordovician reef shoal development tarim basin nw china abstract six types of carbonate platform marginal slope have been identified in the cambrian ordovician of tarim basin these include a progradational carbonate ramp platform a progradational carbonate rimmed platform an aggradational rimmed carbonate platform a retrogradational rimmed carbonate platform an aggradational margin on an isolated carbonate platform and a retrogradational margin on a submerged carbonate platform various platform margin architectures and reef shoal characteristics occur in different areas of the tarim basin a progradational carbonate ramp platform margin began in the early cambrian in the tarim basin a progradational rimmed platform margin developed in the middle cambrian time in the northern tarim basin whereas contemporaneously a progradational ramp platform margin developed in the southwestern and central tarim basin a retrogradational rimmed carbonate platform developed in the northern tarim basin whereas an aggradational rimmed carbonate platform occupied the central tarim basin in the early ordovician time an aggradational margin on an isolated platform and a retrogradational margin on a submerged platform developed mainly during the late ordovician in the central tarim basin platform margin slopes migrated continually throughout the cambro ordovician the broad platform area western tarim platform that occupied most of the northwestern and central tarim basin in the early cambrian time was split by an east west oriented shelf seaway that began to develop along the eastern and western margins of the platform in the early ordovician time and completely transected the platform by late ordovician time the resultant central tarim basin platform area was much reduced elongate east west around the central tarim paleo uplift and terminated eastward towards region of the late ordovician basinal deposition across the eastern tarim basin affected by platform margin structure climate and paleodepth algal reefs and shoals developed mainly in the cambrian and intraclastic shoals developed mainly in the early ordovician followed by reef building of framestone or bafflestone in the late ordovician

steep microbial boundstone dominated plaform margins abstract seaward progradation of several kilometers has been documented mostly for leeward margin low angle carbonate slope systems with a dominant platform top sediment source however steep and high relief margins fronting deep basins can also prograde and as such are somewhat perplexing characteristics of two prograding carboniferous examples provide a model which may apply elsewhere 1 outcrops in asturias northern spain serve as important analogs for 2 hydrocarbon reservoirs in steep sided isolated platforms of the north caspian basin kazakhstan such as tengiz seismic and well data from tengiz corroborate outcrop patterns for slope development showing progradation of up to 5 and more than 10 km respectively despite the high relief up to 600 m and steep 20 35 nature of these margins the two examples share a highly productive microbial boundstone factory extending from the platform break down the slope to nearly 300 m or more depth and a lower slope dominated by mega breccias and grain flow deposits derived from the margin and slope itself the broad depth range of microbial boundstone increases the potential for production during both lowstands and high stands of sea level and thereby facilitates progradation independent from platform top derived sediment rapid in situ lithification of the boundstone provides stability to the steep slopes but also leads to readjustment through shearing and avalanching what controls the microbial cement boundstone formation remains a debate but its presence is a key factor controlling the progradational geometry of these and possibly other margins this new model of slope shedding has implications for slope readjustment processes and resulting architecture sequence stratigraphic interpretation reservoir characterization and reservoir modeling especially the isotropic character of microbial boundstone will reduce the potential for coherent seismic reflections to develop and possibly invoke under certain stress regimes shattering and fracturing thereby generating significant non matrix permeability key considerations are the contrasts with the bahamian high stand shedding depositional model slope progradation rates that range from 450 to 1500 m my and net growth rates of in situ boundstone of 1000 m my comparable to or higher than accretion rates for metazoan skeletal reef growth

the geochemistry of environmentally important trace elements in uk coals with special reference to the parkgate coal in the yorkshire nottinghamshire coalfield uk abstract the parkgate coal of langsettian age in the yorkshire nottinghamshire coalfield is typical of many coals in the uk in that it has a high sulphur s content detailed information on the distribution of the forms of s both laterally and vertically through the seam was known from previous investigations in the present work 38 interval samples from five measured sections of the coal were comprehensively analysed for major minor and trace elements and the significance of the relationships established using both raw and centered log transformed data the major elements are used to quantify the variations in the inorganic and organic coal components and determine the trace element associations pyrite contains nearly all of the hg as se tl and pb and is also the major source of the mo ni cd and sb the clays contain the following elements in decreasing order of association rb cs li ga u cr v sc y bi cu nb sn te and th nearly all of the rb is present in the clay fraction whereas for elements such as v cu and u a significant amount is thought to be present in the organic matter based on the k vs trace element regression equations only ge and possibly be would appear to have a dominant organic source the trace element concentrations are calculated for pyrite the clay fraction and organic matter for pyrite it is noted that concentrations agree with published data from the yorkshire nottinghamshire coalfield and also that tl concentrations median of 0 33 ppm in the pyrite are greater than either hg or cd unlike these elements tl has attracted less attention and possibly more information is needed on its anthropogenic distribution and impacts on man and the environment a seawater source is thought to be responsible for the high concentrations of s cl and the non detrital trace elements in the parkgate coal indicative of the seawater control is the th u ratio which expresses the detrital to non detrital element contributions using other elements similar ratios can be calculated which in combination offer greater interpretative value

accumulation rates from well dated late neogene carbonate platforms and margins abstract margins of large carbonate platforms isolated platforms and atolls are dynamic settings that both generate and accumulate sediments with the exceptions of modern platforms the rates of accumulation are often poorly constrained due to inadequate or unreliable subsurface age data a compilation is here presented of well dated late neogene ice house platform and margin accumulation for the interval from 7 to 2 ma the rates are grouped according to platform type and setting sea level effects and subsidence bathymetry control are the significant influences the six settings are 1 slow aggraded platform 2 partially drowned platform 3 fast aggraded platform 4 atolls 5 prograded margin and 6 periplatform mean rates are 10 to 20 m my for slow aggraded and partially drowned platforms 20 40 m my for atolls and a fast aggraded platform 40 m my for a current dominated prograded margin and 40 110 m my for most prograded and periplatform systems the maximum rates measured from the age depth plot are generally two to three times as high the mean accumulation rates and maximum rates are primarily related to the influence of sea level and to a lesser extent regional subsidence the shallow platforms and atolls are directly sea level controlled whereas the deeper margins are sea level influenced the platform top deposits have the lowest rates of accumulation 10 26 m my due to subaerial exposure and only intermittent flooding the deeper platform margins below lowstand base level are influenced by events on the shallow platform mainly to sediment production and offbank transport slope erosion and redeposition are also important prograded margins and periplatforms accept large volumes of allochthonous sediment and can have periods of extremely high 200 m my vertical accumulation separated by intervals of non deposition erosion or sediment bypass these data despite limitations provide some basic values for ice house carbonate accumulation and the relevant extrinsic controls the late neogene rates can help constrain the sediment dynamics of the carbonate platform and flank system data especially important for calibration of computer models and for the resultant reservoir attributes

characterization of reservoirs fluids and productions from the ordovician carbonate condensate field in the tarim basin northwestern china the tz no1 gas field in the tarim basin is the largest condensate field in china however it has not developed efficiently because of low and unpredictable production during the past 20 yr cores logging interpretation seismic descriptions fluid properties and production data indicate that this ordovician carbonate field is different from conventional stratigraphic oil and gas fields as follows 1 the hydrocarbon bearing area covers a large region of 2000 km2 2 matrix reservoirs have low porosity 20 per year an examination of the carbonate reservoir and hydrocarbon accumulation history suggests that this large scale stratigraphic accumulation formed during hydrocarbon emplacement in the early paleozoic with the reservoirs gradually evolving into tight reservoirs as a result of intense diagenesis variable amounts of neogene gas charged the tight carbonate reservoirs and formed unconventional accumulations the tz no1 gas field is characterized by a strongly heterogeneous tight matrix reservoir with a superimposed fracture cave reservoir and a complicated unconventional fluid distribution which provides insights into the exploitation challenges of unconventional carbonate resources

slope sedimentation associated with a vertically building shelf bone spring formation mescalero escarpe field southeastern new mexico mescalero escarpe field contains slope strata in the bone spring formation which provide insight into development of the northwestern shelf to the north and the delaware basin to the south during the leonardian permian the northwestern shelf grew vertically due to regional subsidence and cyclic sedimentation slope facies include 1 dolomitized peloid bioclast packstone 2 dolomite megabreccia 3 laminated dolomitic mudstone and 4 very fine grained sandstone oil is produced from peloid bioclast packstones and megabreccias stratigraphic relationships indicate carbonate sedimentation in slope and basinal environments contemporaneous with carbonate sedimentation on the shelf peloid bioclast packstones overlain by megabreccias are present at the toe of slope and dolomitic mudstones occur higher on the slope and deeper in the basin basinal sandstones are present between those carbonate strata seismic data show erosion and backstepping of the shelf margin correlative with megabreccia deposition at the toe of slope lithologic and stable isotope data suggest that erosion of the shelf took place in sea water depositional cycles are related to sea level cycles 1 during rapid sea level rises the shelf was flooded and carbonate sedimentation initiated sediment swept off the shelf formed peloid bioclast packstones at the toe of slope and dolomitic mudstones in other slope and basinal environments 2 as sea levelmore rise slowed or stopped the shelf approached sea level the shelf margin was eroded and debris flows transported eroded detritus to the toe of slope and megabreccias formed deposition of carbonate mud continued in adjacent environments 3 when sea level stayed still or dropped the shelf was at sea level or emergent and terrigenous sand was transported into the basin less

pyrite framboids and their development a new conceptual mechanism it has been suggested that the two morphologies of sedimentary pyrite framboids and euhedra may reflect two distinct pathways of pyrite formation framboids form indirectly via iron monosulphides whereas euhedra form from direct precipitation from solution a third pathway which is bridging these two forms is proposed here namely the continuous growth from a monosulphide globule through framboids to a euhedral single crystal it is also suggested that framboids probably occur over a range of three orders of magnitude from the least complex microframboids through framboids to polyframboids

carbonate platform flanks slope angle and sediment fabric more than 20 examples of fossil carbonate platform systems were compared for slope angle and sediment fabric plots of slope angle versus sediment fabric show that grainy non cohesive mud free sediments build steeper slopes than muddy cohesive sediments examples near the end members of grainy and muddy carbonate platform flanks are found in the triassic of the dolomites in northern italy and in the bahamas respectively they document the flank geometry and the processes readjusting the slope profile once the limiting slope angle is exceeded the grainy flank sediments in the dolomites modified by shearing and avalanching produce straight slope profiles with declivities up to 35 whereas the muddy bahamian flank sediments modified by large scale creep and rotational to translational sliding and slumping produce a concave upwards slope profile inclined at less than 4 the comparison between slope angle and sediment fabric indicates that the physical behaviour of sediments in the gravity field angle of shearing and mode of readjustment processes is linked to the composition of the slope sediment among the variables such as sea level subsidence climate plate motion and oceanographic setting windward leeward sediment fabric is suggested to be a major if not the major control on slope angle and slope curvature of carbonate platform flanks besides the recently documented tendency of carbonate sediments to build steeper slopes than siliciclastics this proposed relation sheds new light on the analysis and quantification of the variables influencing the geometry and depositional evolution of carbonate systems furthermore it provides an opportunity to deduce sediment composition from seismic lines and predict lithology prior to drilling

mineral and inorganic chemical composition of the pernik coal bulgaria the mineral and inorganic chemical composition of five types of samples from the pernik subbituminous coals and their products generated from the pernik preparation plant were studied they include feed coal low grade coal high grade coal coal slime and host rock the mineral matter of the coals contains 44 species that belong mainly to silicates carbonates sulphates sulphides and oxides hydroxides and to a lesser extent chlorides biogenic minerals and organic minerals the detrital minerals are quartz kaolinite micas feldspars magnetite cristobalite spessartine and amphibole the authigenic minerals include various sulphides silicates oxihydroxides sulphates and carbonates several stages and substages of formation were identified during the syngenetic and epigenetic mineral precipitations of these coals the authigenic minerals show the greatest diversity of mineral species as the epigenetic mineralization mostly sulphides carbonates and sulphates dominates qualitatively and quantitatively the epigenetic mineralization was a result of complex processes occurring mostly during the late development of the pernik basin these processes indicate intensive tectonic hydrothermal and volcanic activities accompanied by a change from fresh to marine sedimentation environment thermally altered organic matter due to some of the above processes was also identified in the basin most of the trace elements in the pernik coals mo be s zr y cl ba sc ga ag v p br ni co pb ca and ti show an affinity to om and phases intimately associated with om some of the trace elements sr ti mn ba pb cu zn co cr ni as ag yb sn ga ge etc are impurities in authigenic and accessory minerals while other trace elements la ba cu ce sb bi zn pb cd nd etc occur as discrete phases elements such as sc be y ba v zr s mo ti and ga exceed clarke concentrations in all of the coal types studied it was also found that a number of elements in the pernik coals f v as pb mo li sr ti ga ni ge cr mn etc reveal mobility in water and could have some environmental concerns

shale gas accumulation potential of the upper cretaceous qingshankou formation in the southeast songliao basin ne china abstract the purpose of this paper is to provide both quantitative and qualitative visual analyses of the nanometer scale pore systems of immature and early shales as well as to discuss the biogenic shale gas accumulation potential of the upper cretaceous section of the songliao basin to achieve these goals mineralogical compositions were determined using transmitted and reflected light petrography x ray diffractometry and scanning electron microscopy sem while the nanostructure morphology and pore size distributions psds were quantified using field emission scanning electron microscopy fe sem and low pressure nitrogen gas adsorption lp n2ga the results of these analyses indicate that nanometer scale pores are well developed in the immature and low maturity shale and that these shales contain many types of reservoir pores the mudstone layer of the qingshankou formation k2qn contains a high permeability characteristic and good rock fracturing conditions while it is also thick 9 m in thickness and rich in fine organic matter overall analysis of the entire formation using source rock and reservoir evaluations indicate that the first member of the qingshankou formation k2qn1 has a greater shale gas accumulation potential than the second and third members of the qingshankou formation k2qn2 3

tectonic controls on carbonate platform evolution in southern papua new guinea passive margin to foreland basin the middle oligocene collision of the northern margin of the australian craton with a complex subduction system resulted in emplacement of a thrust mass and formation of a foreland basin that extended from the coral sea to the indian ocean the distribution of carbonate platform facies in southwestern papua new guinea reflects the transition from an eocene passive margin setting to the early stages of foreland basin evolution the initial basin configuration with terrigenous sedimentation confined to the proximal foredeep allowed carbonate deposition in the shallow environment adjacent to the peripheral forebulge subsequent southward migration of the basin resulted in a rapid increase in the area and thickness of carbonate platform deposition when the proximal foredeep became filled by detritus shed from the emerging orogen clastic sediments buried the platform and terminated carbonate deposition the history of the southern papua new guinea carbonate platform illustrates the paradox of carbonate deposition within the foreland basin whereby basin configuration initially encourages thick and extensive carbonate deposition but inevitably leads to terrigenous inundation and the demise of the carbonate platform

increased terrigenous influx but no drowning palaeoenvironmental evolution of the tunisian carbonate platform margin during the late aptian during the aptian some carbonate platforms of the sub tropical realm for example on the northern tethys margin or in the gulf of mexico were affected repeatedly by severe perturbations in the carbonate production factory and drowning preferentially during global warming events such as the early aptian oceanic anoxic event 1a and a prominent mid late aptian warming interval these platform growth crises have been explained mainly by strongly increased coastal runoff for example siliciclastics and nutrients in combination with pronounced eustatic sea level rises in the last few years increasing evidence suggests that carbonate platforms of lower latitudes were generally less or even not affected by environmental perturbations during these events this raises the question as to the responsible factors that promoted platform growth or decline in different latitudinal areas in this study upper aptian middle gargasian to uppermost clansayesian inner tropical carbonate ramp deposits of the serdj formation at djebel serdj north central tunisia are studied in detail with regard to microfacies lithology biostratigraphy and chemostratigraphy these data allow reconstruction of the palaeoenvironmental evolution of the tunisian carbonate platform margin and investigation of its response to the prominent mid late aptian warming interval the unusually expanded 600 m thick serdj formation consists of limestones marlstones and siltstones suggesting deposition within mid ramp to inner ramp palaeoenvironments deposits of the mid late aptian are represented by quartz rich platform carbonates and siltstones probably resulting from increased coastal runoff on the tunisian shelf as a response to global warming and accelerated water cycling the siliciclastic input was accompanied by elevated nutrient levels as indicated by a partial decline in the abundance of oligotrophic biota and mass occurrences of orbitolines and green algae carbonate platform drowning during the mid late aptian as reported from the sub tropical realm has not been identified a comparison with other tropical river influenced platforms suggests that none of them drowned during the mid late aptian one important reason might be widespread arid to semi arid climatic conditions within lower latitudes during that time promoting platform growth due to comparably low nutrient runoff

petrological geochemical and mineralogical compositions of the low ge coals from the shengli coalfield china a comparative study with ge rich coals and a formation model for coal hosted ge ore deposit abstract to better understand the formation mechanism of coal hosted ge ore deposits this paper reports on the petrological mineralogical and geochemical compositions of the low ge coals in the shengli coalfield inner mongolia china using optical microscopy field emission scanning electron microscopy x ray fluorescence x ray diffraction and inductively coupled plasma mass spectrometry the samples in the present study closely neighbor the previously reported wulantuga coal hosted ge ore deposit both no 6 coal in comparison with the wulantuga ge rich coals the low ge coals of the shengli field display higher moisture 27 59 on average and lower pyritic sulfur contents 0 53 both the low ge and ge rich coals are generally high in inertinite and have varying but relatively low huminite contents preservation of fecal pellets as macrinite is notable in both the low ge and ge rich coals and the position of the fecal pellets appears to be within tunnels or chambers within the wood quartz kaolinite pyrite and gypsum are the major crystalline phases identified in most of the ge rich and low ge coals but the low ge coals contain significantly less pyrite and are more abundant in non mineral ca and mg ca oxalate of authigenic origin is observed generally occurring as cell fillings in the low ge coals otherwise mineral free organic matter in the low ge coals would be expected to have an inherent ash yield of around 6 derived from the inorganic elements mainly non mineral ca and mg that occur either in the organic matter or as dissolved ions in the pore water and form the sulfate species in low temperature oxygen plasma ash residues the highly elevated trace elements including be ge as sb w hg and tl that occur in the ge rich coals of the wulantuga deposit are significantly depleted in the low ge coals lateral migration of ge w and as hg sb tl rich solutions through the original peat swamp for the wulantuga ge ore deposit has led to significant enrichment of ge on the margin of the coal basin but decreasing ge concentrations toward to the inner part of the basin such a migration direction is different to those in the previously reported for the hydrothermal solutions in the lincang yunnan of china and spetzugli russian far east ge ore deposits where the solutions migrated vertically from granite to peat along faults and led to a dome shaped ge distribution in the relevant coal seam

pore characteristics of longmaxi shale gas reservoir in the northwest of guizhou china investigations using small angle neutron scattering sans helium pycnometry and gas sorption isotherm abstract small angle neutron scattering sans helium pycnometry and low pressure gas sorption isotherm experiments were used to investigate the pore characteristics of longmaxi shale the leading producing formation in china this work is the first microstructural study of chinese marine shales by neutron scattering technique the polydisperse spheres model pdsp was used for sans data analysis to obtain porosity and pore size distribution psd and the results were compared with those from gas co2 n2 adsorption and helium pycnometry by evaluating the difference of porosities determined from these methods the closed fraction of shale pores are derived and discussed moreover the porosity has a positive correlation with total organic carbon toc in longmaxi shale samples the fractal dimension of shale samples was derived and results indicated that longmaxi shale is a mass fractal a lower mass fractal dimension means less closed pores with correspondingly more open structures

geochemistry mineralogy and technological properties of coals from rio maior portugal and penarroya spain basins abstract this study focuses on the geochemistry and mineralogy of pliocene lignites from the rio maior basin portugal and of late westphalian bituminous and anthracite coals from the penarroya basin spain major mineral phases present in the rio maior lignites are quartz and clay minerals with minor amounts of other detrital minerals depending on the sedimentary environment and the source of the detrital input the concentration of rb cs sc v u and gd in lignites is higher than the maximum value established for the usual worldwide concentration range for coal geochemical affinity study for major and trace elements in rio maior established three major associations i aluminium silicate affinity fe mg na k li rb sc zr v cr co ni se pb sb gd and tb ii the sulphur affinity mo and as and iii organic affinity sr ca mn ba and u ce and cs affinities could not be explained with the available data in the penarroya bituminous coals the main mineral phases identified were quartz and clay minerals kaolinite and illite minor traces of anatase and epigenetic carbonates elements with inorganic affinity fe mg na k ti li rb cs ba sc zr v cr co ni pb u se ce gd tb cu have a high to medium aluminium silicate affinity anomalous concentrations of li rb cs sc v and cr could be related to the input of detrital minerals from the precambrian and lower palaeozoic rocks in the northeastern part of penarroya basin anthracites from the penarroya basin have the following mineral phases calcium iron and magnesium carbonates clay minerals and quartz as well as traces of apatite and of pyrite carbonates and some kaolinite are clearly epigenetic as a consequence of fluid circulation related to magmatic activity two main geochemical associations were found i aluminium silicate affinity na k ti rb cs ba sc cr mo ni cd as sb se ce gd tb cu and ii carbonate affinity ca mg fe v mn sr an anomalous amount of mn and v is considered to be related with the circulation of magmatic fluids the geochemical and mineralogical variations observed were primarily related to coal rank in the penarroya basin whilst paleoenvironmental depositional conditions were more important in the rio maior basin the chemical composition of the high temperature ashes is related to the trend followed by the ash fusion temperatures and to the predictive indices associated with slagging and fouling propensities these indices indicate low to medium slagging and fouling propensities for all the coals studied

influential factors and model of shale pore evolution a case study of a continental shale from the ordos basin abstract pore characteristics have a significant influence on the occurrence and enrichment of shale gas therefore these characteristics are key parameters in shale reservoir evaluation and have important research significance taking a continental shale sample from the ordos basin china as an example this research used low pressure co2 n2 adsorption high pressure mercury intrusion porosimetry mip vitrinite reflectance ro analysis hydrocarbon generation measurements x ray diffraction analysis and argon ion polishing field emission scanning electron microscopy aip fesem in conjunction with a thermal simulation experiment to study pore characteristics through the above analyses this study achieved a whole aperture dynamic characterization of the shale pores and discussed the characteristics of the shale pore distribution and evolution through geological history then the factors influencing pore evolution were analysed and a pore evolution model was established the results showed that the micropores and mesopores provided the majority of the surface area in the sample while the mesopores and macropores provided the majority of the pore volume in the sample during the thermal simulation experiment pore evolution was dominated by the hydrocarbon generation by organic matter the transformation of minerals and compaction according to the pore evolution characteristics and the main influential factors during the thermal simulation experiment the pore evolution model can be divided into four stages the characteristics of the micropores mesopores macropores and the influential factors differ in each stage

genetic types of carbonate shoal reservoirs in the middle triassic of the sichuan basin sw china abstract carbonate shoal reservoirs of the middle triassic leikoupo formation in the sichuan basin were investigated for potential gas resources the carbonate shoal reservoirs can be divided on the basis of their formation mechanism into residual intergranular pore karst further divided into syndepositional burial and epigenetic karstification types dolomitized and composite reservoirs residual intergranular pores and dissolved pores are the main reservoir spaces in the residual intergranular pore reservoirs isolated intragranular corroded pores and moldic pores are the main reservoir spaces in syndepositional karstification reservoirs the main spaces in burial karstification reservoirs are dissolved pores and holes and pores and caves on various scales are the main reservoir spaces of epigenetic karstification reservoirs intercrystal pores and intercrystal solution pores are the main reservoir spaces of dolomitized reservoirs composite reservoirs are characterized by a variety of reservoir spaces with pores holes and fissures high quality shoal reservoirs were formed by superposition of carbonate shoals and constructive diagenetic modification preservation of residual intergranular pores was crucial for development of residual intergranular pore reservoirs platform interior micro highlands relative declines in sea level and rainfall controlled the development of syndepositional karstification reservoirs dissolution by unsaturated acidic fluids pre existing pores and pore throats and the direction of corrosive fluid flow were important for burial karstification reservoirs epigenetic karstification reservoirs formed as a result of significant sea level drops or tectonic movement dolomitized reservoirs formed in shoals affected by dolomitization caused by evaporation of seawater or that occurred during burial composite shoal reservoirs were formed by two or more processes

porosity of coal and shale insights from gas adsorption and sans usans techniques two pennsylvanian coal samples spr326 and spr879 in1 and two upper devonian mississippian shale samples mm1 and mm3 from the illinois basin were studied with regard to their porosity and pore accessibility shale samples are early mature stage as indicated by vitrinite reflectance ro values of 0 55 for mm1 and 0 62 for mm3 the coal samples studied are of comparable maturity to the shale samples having vitrinite reflectance of 0 52 spr326 and 0 62 spr879 in1 gas n2 and co2 adsorption and small angle and ultrasmall angle neutron scattering techniques sans usans were used to understand differences in the porosity characteristics of the samples the results demonstrate that there is a major difference in mesopore 2 50 nm size distribution between the coal and shale samples while there was a close similarity in micropore 2 nm size distribution micropore and mesopore volumes correlate with organic matter content in the samples accessibility of pores in coal is pore size specific and

analysis origin and significance of mineral matter in coal an updated review abstract the material classed as mineral matter in coal embraces crystalline mineral materials as well as a range of inorganic elements that occur in non crystalline form this review outlines the methods that may be used to evaluate the percentage of mineral matter for a coal sample as opposed to the ash yield and to identify the minerals their individual percentages and their modes of occurrence within the coal the principal techniques include low temperature oxygen plasma ashing quantitative evaluation of x ray diffraction data observation using optical microscopy and a combination of observation chemical analysis and in some cases mapping based on scanning electron microscopy and related methods a range of other techniques may also be used to provide additional information on particular mineral matter components processes responsible for mineral matter formation include detrital input biogenic activity and authigenic precipitation at different stages of the coal s depositional and post depositional history differential migration of non mineral inorganic elements may also occur in lower rank coals and expulsion of non mineral inorganics may take place with rank advance knowledge of the mineral matter may be of assistance in understanding the modes of trace element occurrence with implications for assessing possible environmental impacts and also the potential for recovery of economic products from coal the behaviour of different mineral matter components at high temperatures is also discussed as well as methods for mineralogical analysis of ashes and other coal utilization products information from mineral matter studies may provide an improved basis for understanding coal formation and for evaluating the response of particular coals to different combustion gasification and coking processes

microfracturing and microporosity in shales shales are ubiquitous rocks in sedimentary basins where their low permeability makes them efficient seals for conventional oil and gas reservoirs and underground waste storage repositories waste waters co2 nuclear fuels moreover when they contain organic matter they form source rocks for hydrocarbons that may escape towards a more porous reservoir during burial a process referred to as primary migration and when the hydrocarbons cannot escape these rocks can be exploited as oil or shale gas reservoirs while the presence of fractures at the outcrop scale has been described the existence of fractures at smaller scales their link with microporosity the mechanisms that created them their persistence over geological times and their effect on the petrophysical properties of shales represent scientific challenges for which drillings in various sedimentary basins over the past decades may hold timely key data here we review and synthetize the current knowledge on how microfractures and micropores in shales can be imaged and characterized and how they control their anisotropic mechanical properties and permeability one question is whether such microfractures when observed in outcrops or in drilled core samples extracted from boreholes are related to decompaction and do not exist at depth another question is whether veins observed in shales represent microfractures that were open long enough to have acted as flow paths across the formation the mechanisms of microfracture development are described some have an internal origin fracturing by maturation of organic matter dehydration of clays while others are caused by external factors tectonic loading importantly the amount of microfracturing in shales is shown to depend strongly on the content in 1 organic matter and 2 strong minerals the nucleation of microfractures depends on the existence of mechanical heterogeneities down to the nanometer scale their propagation and linkage to create a percolating network will depend on the presence of heterogeneities at the meso to macro scales such percolating microfracture networks could control both the long term sealing capabilities of cap rocks and the further propagation of hydraulic fracturing cracks finally possible areas of research for describing the mechanism of microfracture formation in greater detail and how this impacts the transport and mechanical properties of shales are also discussed

characterization of the co2 fluid adsorption in coal as a function of pressure using neutron scattering techniques sans and usans abstract small angle neutron scattering techniques have been applied to investigate the phase behavior of co2 injected into coal and possible changes in the coal pore structure that may result from this injection three coals were selected for this study the seelyville coal from the illinois basin ro 0 53 baralaba coal from the bowen basin ro 0 67 and bulli 4 coal from the sydney basin ro 1 42 the coals were selected from different depths to represent the range of the underground co2 conditions from subcritical to supercritical which may be realized in the deep subsurface environment the experiments were conducted in a high pressure cell and co2 was injected under a range of pressure conditions including those corresponding to in situ hydrostatic subsurface conditions for each coal our experiments indicate that the porous matrix of all coals remains essentially unchanged after exposure to co2 at pressures up to 200 bar 1 bar 105 pa each coal responds differently to the co2 exposure and this response appears to be different in pores of various sizes within the same coal for the seelyville coal at reservoir conditions 16 c 50 bar co2 condenses from a gas into liquid which leads to increased average fluid density in the pores pore with sizes r 1 105 r 1 104 a pore 0 489 g cm3 as well as in small pores with size between 30 and 300 a pore 0 671 g cm3 these values are by a factor of three to four higher than the density of bulk co2 co2 under similar thermodynamic conditions co2 0 15 g cm3 at the same time in the intermediate size pores with r 1000 a the average fluid density is similar to the density of bulk fluid which indicates that adsorption does not occur in these pores at in situ conditions for the baralaba coal 35 oc 100 bar the average fluid density of co2 in all pores is lower than that of the bulk fluid pore co2 0 6 neutron scattering from the bulli 4 coal did not show any significant variation with pressure a phenomenon which we assign to the extremely small amount of porosity of this coal in the pore size range between 35 and 100 000 a

differences between reservoirs in the intra platform and platform margin reef shoal complexes of the upper ordovician lianglitag formation in the tazhong oil field nw china and corresponding exploration strategies abstract the upper ordovician lianglitag formation in the tazhong oil field nw china is dominantly composed of shallow marine carbonates and it can be subdivided into five members lithologically unclear understanding of the reservoir evolution in the platform margin and intra platform reef shoal complexes resulted in difficulty in locating reservoirs and poor drilling success in the intra platform by comparing the basic characteristics diagenesis and porosity evolution of the two types of reservoirs this study established their development patterns and proposed corresponding exploration strategies based on comprehensive analysis of core thin section well logging three dimensional seismic and geochemistry data the major difference between the platform margin and intra platform reservoirs lied in their pore types the platform margin reservoirs had fabric selective intragranular dissolution pores intergranular dissolution pores moldic pores and non fabric selective karst fractures and caves and tectonic fractures whereas the intra platform ones only had tectonic fractures intercrystalline dissolution pores and intergranular vugs in terms of distribution the platform margin reservoirs were mainly distributed in the parasequence top and landform highlands of the highstand system tract in members 3 to 1 appearing in two to six cycles with large single layer and accumulative thicknesses and a quasi bedded continuous distribution in the lateral however the distribution of the intra platform ones was not obviously correlated with sedimentary facies and paleogeomorphology with smaller single layer and accumulative thicknesses and poorer lateral continuity the evolution and distribution of high quality reservoirs in the platform margin were jointly controlled by eogenetic marine diagenetic and meteoric dissolution including karst burial dissolution and tectonic fractures in comparison eogenetic marine diagenetic and meteoric dissolution in the intra platform reef shoal complexes were weak accompanied by persistent cementation the favorable reservoirs were primarily controlled by fractures and later burial dissolution hence for the exploration of the platform margin reef shoal complex reservoirs the priority should be given to the areas with the superimposition of eogenetic marine diagenetic and meteoric dissolution burial dissolution and tectonic fracturing for the exploration of intra platform reef shoal complex reservoirs more attention should be paid to areas with overlapped fractures and burial dissolution especially where hercynian strike slip faults and early fractures were superimposed less attention should be paid to the areas with eogenetic marine diagenetic and meteoric dissolution

mineralogy of lignites and associated strata in the mavropigi field of the ptolemais basin northern greece the mineralogy of five lignite layers and the associated roof floor and intercalating strata has been analysed using low temperature oxygen plasma ashing and quantitative x ray diffraction techniques the lignite contains quartz kaolinite illite and smectite and in some cases small proportions of feldspar thought to represent mainly detrital minerals in the original peat deposits one sample also contains crystalline calcium oxalates with weddellite present in the raw lignite and whewellite in the low temperature ash lta of the same lignite sample minor proportions of gypsum are present in some of the raw lignite samples possibly in part derived from precipitation of dissolved ca and so4 in the pore waters on drying all the ltas however contain much higher proportions of bassanite and or gypsum compared to the other minerals present consistent with production of calcium sulphate artefacts from interaction of abundant organically associated ca and s in the lignite during the plasma ashing procedure the inorganic strata are mainly carbonate rocks consisting almost entirely of calcite with minor aragonite small proportions of illite traces of pyrite and in some cases siderite some non carbonate rocks are also associated with the lignite seams these are dominated by plagioclase feldspar and mica along with illite kaolinite and a relatively minor proportion of quartz the mineral assemblages can be related to the palaeoenvironmental conditions under which the various sediments including lignite were deposited comparison of the mineral abundances in the samples to the chemical composition of the materials shows that the quantitative xrd technique provides results consistent with ash analysis data although abundant in the associated rocks calcite does not occur in the lignite samples while part of the relatively abundant ca in the lignite occurs as either gypsum or weddellite most of it appears to be organically bound mine products that incorporate calcareous rocks of the type associated with the lignite may however contain separate calcite phases and display high carbonate co2 contents

small angle neutron scattering signature of oil generation in artificially and naturally matured hydrocarbon source rocks abstract we have demonstrated for the first time the application of a small angle neutron scattering sans technique for the precise determination of the onset of hydrocarbon transport primary migration in shaly source rocks we used a sequence of rocks pyrolysed in the laboratory under nitrogen at temperatures in the range 310 370 c these rocks contained several percent of dispersed marine type ii organic matter geochemical analysis indicated a peak of the hydrocarbon generation in the middle of the temperature range at 340 c we observed a sharp decrease of sans intensity in a narrow maturity range within the geochemically determined region of the onset of hydrocarbon generation this decrease was a direct consequence of the sans contrast variation caused by the invasion of the pore space by bitumen during the primary migration of hydrocarbons a similar phenomenon was observed for a natural maturity sequence of source rocks originating from the same location

geochemistry of trace elements in chinese coals a review of abundances genetic types impacts on human health and industrial utilization abstract china will continue to be one of the largest coal producers and users in the world the high volume of coal use in china has focused attention on the amounts of toxic trace elements released from coal combustions and also the valuable trace elements extracted or potentially utilized from coal ash compared to world coals chinese coals have normal background values for most trace elements with the exception of higher li 31 8 g g zr 89 5 g g nb 9 44 g g ta 0 62 g g hf 3 71 g g th 5 84 g g and rare earth elements la lu y 136 g g this is not only due to the higher ash yields of chinese coals but also to alkali volcanic ashes found in some southwestern coals the background values of toxic elements of hg 0 163 g g as 3 79 g g and f 130 g g in chinese coals are comparable to coals from most other countries the genetic types for trace element enrichment of chinese coals include source rock controlled marine environment controlled hydrothermal fluid controlled including magmatic low temperature hydrothermal fluid and submarine exhalation controlled subtypes groundwater controlled and volcanic ash controlled the background values of trace elements were dominated by sediment source regions low temperature hydrothermal fluid was one of the major factors for the local enrichment of trace elements in southwestern china serious human health problems caused by indoor combustion of coal in china include endemic fluorosis arsenosis selenosis and lung cancer endemic fluorosis mainly occurring in western guizhou was mostly attributed to the high fluorine in clay that was used as a briquette binder for fine coals in addition to a small quantity of fluorine from coal fluorine in the coal from endemic fluorosis areas of western guizhou is within the usual range found in china and the world endemic arsenosis in southwestern guizhou is attributed to indoor combustion of high as coal endemic selenosis in enshi of hubei was due to high se in carbonaceous siliceous rocks and carbonaceous shales fine particles of quartz released into air during coal combustion are hypothesized as a possible cause for the lung cancer epidemic in xuanwei yunnan china valuable elements including ge ga u ree rare earth element nb zr and re are concentrated to levels comparable to conventional economic deposits in several coals or coal bearing strata in china the ge deposits at lincang yunnan province and wulantuga inner mongolia have been exploited and industrially utilized the enrichment of ge in the two deposits was caused by hydrothermal fluids associated with adjacent granitoids the ga al ore deposit in the jungar coalfield inner mongolia was derived from the neighboring weathered and oxidized bauxite of the benxi formation pennsylvanian the nb ta zr hf ree ga deposits in the late permian coal bearing strata of eastern yunnan and chongqing of southwestern china were attributed to ashes of the alkali volcanic eruptions

genesis of upper cambrian lower ordovician dolomites in the tahe oilfield tarim basin nw china several limitations from petrology geochemistry and fluid inclusions abstract thick upper cambrian lower ordovician carbonate units in the tahe oilfield of northern tarim basin were extensively dolomitized during their diagenetic history petrographic examination identified three types of matrix dolomites one type of cement dolomite and one type of saddle dolomite in these units micritic to very finely crystalline nonplanar matrix dolomite d1 finely crystalline planar s e matrix dolomite d2 medium to coarsely crystalline nonplanar a matrix dolomite d3 finely to medium crystalline planar e cement dolomite cd and coarsely crystalline planar s to nonplanar saddle dolomite sd isotopic studies c o and sr elements measurements and fluid inclusion analysis were combined to constrain the origins of dolomitizing fluids the occurrence of near micritic dolomite crystals as well as isotopic compositions which are consistent with the values and ratios of upper cambrian lower ordovician marine limestones coupled with the rare earth elements ree patterns with negative ce anomalies collectively suggest precipitation of d1 dolomite at low temperatures of near surface settings from mesosaline to penesaline seawater d1 dolomite characterized by high mg ca ratios and mgo values moderate sr concentrations and low mn and fe values was formed in the early diagenetic stage and scarcely experienced recrystallization the dolomitizing fluid of d2 dolomite was derived from connate seawaters resulting from mechanical compaction and burial dissolution under shallow burial conditions which is indicated by textures isotopic compositions and ree patterns the relatively low mgo contents and mg ca ratios constrain the formation of the d2 dolomite to a closed diagenetic system with a limited local supply of mg2 ions the large overlaps of isotopic compositions between d3 dolomite and earlier dolomite as well as the similar ree patterns and depleted sr contents indicate that d3 dolomite was likely the result of intense recrystallization upon previous matrix dolomites in a deeply buried formation fluid system the petrographic features and geochemical attributes of cd dolomite strongly indicate progressive growth or recrystallization in the burial environment inclusions with high temperatures developed only in the outer edges of cd crystals demonstrate diffusionally mediated recrystallization during the later hydrothermal activity sd dolomite is interpreted to directly precipitate from hydrothermal fluids as evidenced by high homogenization temperature measured from fluid inclusions and high sr contents high salinity levels suggesting the existence of a very saline fluid deep basinal brine the enriched radiogenic strontium isotope coupled with positive eu anomalies indicate that hydrothermal fluids are likely to be crustal magmatic since early hercynian orogeny long period tectonic activities were responsible for the hydrothermal alteration high angle faulting which appeared as strike slip faulting initiated along basement rooted faults likely acted as the important pathway that channeled the hydrothermal fluids from the depths initially hydrothermal fluids with elevated pressure high temperature and low fluid rock conditions were likely responsible for hydrofracturing and brecciation when distal fluids of cooler temperatures flowed into permeable formations the open fluid dominated system with higher fluid rock conditions facilitated the occurrence of dissolution vugs and precipitation of sd dolomite this study provides a basis for understanding the deep burial carbonate reservoirs in tarim basin by clarifying the process of dolomitization

silicate microspherules intercepted in the plume of etna volcano a possible volcanic origin has been suggested for the micrometre sized spherules that have been discovered in polar snows or ice cores1 5 and in the stratosphere6 7 however although such particles especially when black and magnetic have been identified among the tephra deposits of some volcanoes3 8 12 their volcanic emission has never been directly observed here we describe micro spherules intercepted in the plume of mount etna sicily during moderate recurring volcanic activity their study using analytical transmission and scanning electron microscopy atem and asem demonstrates the simultaneous presence in the plume of glassy silicate microspherules of various chemical compositions 47 98 sio2

quantification of mineral matter in the argonne premium coals using interactive rietveld based x ray diffraction abstract the mineral matter in the eight reference north american coal samples of the argonne premium coal series has been investigated on a quantitative basis using x ray diffraction xrd techniques x ray diffraction data obtained from electronic low temperature oxygen plasma ash lta residues from ashes produced by heating the coals in air at 370 c and also from the raw coals themselves were evaluated using an interactive data processing system siroquant based on rietveld interpretation methods the results from the three types of material lta 370 c ash and raw coal were compared for each sample this allowed the components present in the raw coals in crystalline form to be recognised separately from mineral artifacts produced particularly in the low rank coals from interaction of organically associated elements ca s etc during the two ashing processes after the allowance for the production of any artifacts the quantitative mineral assemblages identified from xrd of the raw coals were found to be consistent even for coals having a relatively low ash percentage around 5 with the results obtained from the respective mineral concentrates prepared by the ashing methods the effects of heating the coal to 370 c could also be distinguished relative to the raw coal or the lta through changes in components such as pyrite and the clay minerals although some areas of uncertainty exist particularly with magnesium in the low rank coals the calculated chemical compositions of the coal ash derived from the mineral mixtures identified for each coal were also found to be consistent with the results of direct chemical analysis of the respective coal ash materials

neutron scattering study of vitrinite insights into sub micrometer inclusions in north american carboniferous coals of bituminous rank abstract results of sans and usans measurements performed on a series of six vitrinite samples having vitrinite reflectance ro values ranging from 0 55 high volatile bituminous rank to 1 28 medium volatile bituminous rank were analyzed experimental data were acquired for two sample forms platelets cut parallel to the bedding and pellets made up of randomly oriented nearly monodisperse particles numerical analysis indicates the presence of sub micron sized inclusions embedded in the organic matrix for the lowest rank vitrinites the dominating inclusions are monodisperse are 7 12 nm in diameter and have concentrations of the order of 1017 cm 3 their shape is anisotropic with the surface to volume ratio about three times larger than for a solid sphere the higher rank vitrinites contain much larger monodisperse inclusions having diameters of 50 nm concentrations of 1014 cm 3 large surface to volume ratios and fuzzy interfaces with the organic matrix inclusions of a similar size and concentration are also present in the lowest rank sample but are much less frequent than the small inclusions we provisionally interpret those objects as inclusions of mineral matter most likely associated with original plant material the internal specific surface area ssa calculated for the small mineral matter inclusions is 100 m2 cm3 and for the large inclusions 2 m2 cm3

the iberian middle jurassic carbonate platform system synthesis of the palaeogeographic elements of its eastern margin spain abstract during the middle jurassic the domain of the iberian and catalan coastal ranges of eastern spain was occupied by a system of fault controlled carbonate platforms that flanked the iberian massif to the east this platform system marked the transition between the shelves of the alpine tethys and the central atlantic ocean the palaeogeographic reconstruction of the iberian middle jurassic platform system is based on more than 199 surface sections and 37 wells from southwest to northeast eight main palaeogeographic elements with associated characteristic facies are recognized these represent a system of horsts and grabens in the southwest the internal castilian platform is characterized by the frequently dolomitized oolitic and restricted facies of the yemeda formation to the northeast the nw trending open marine carbonate environments of the external castilian and aragonese platforms were separated by the fault controlled el maestrazgo high that is characterized mainly by the dolomitized rafales formation the external castilian and aragonese platforms consist from bottom to top of the microfilament mudstones to wackestones of the el pedregal formation the bioclastic and oolitic grainstones to packstones of the moscardon formation and the domeno formation that reflects a return to an open marine low energy wackestone to mudstone facies locally containing patches of oolitic grainstones the highly subsiding tortosa platform represented by the sant blai cardo and la tossa formations is bounded by the dolomitic facies deposited on the el maestrazgo and the tarragona highs and by the catalan massif where no middle jurassic deposits have been recorded the open marine facies and condensed sections of the beceite strait separated the aragonese and tortosa platforms a regional stratigraphical gap spanning the upper callovian lamberti zone to the lower oxfordian cordatum zone is evident a system of northwest and northeast trending normal faults controlled thickness and facies distribution data from the iberian carbonate platform system indicate that expanded sections were not necessarily associated with open marine environments condensed and expanded sections are developed in open and restricted marine facies even on such palaeogeographic highs as the el maestrazgo high restricted and shallow marine environments occasionally developed in parts of the external castilian platform

tracking metamorphic dehydration reactions in real time with transmission small and wide angle synchrotron x ray scattering the case of gypsum dehydration we present a review of a unique non destructive method for the real time monitoring of phase transformations and nano pore evolution in dehydrating rocks transmission small and wide angle synchrotron x ray scattering saxs waxs it is shown how saxs waxs can be applied to investigating rock samples dehydrated in a purpose built loading cell that allows the coeval application of high temperature axial confinement and fluid pressure or flow to the specimen because synchrotron sources deliver extremely bright monochromatic x rays across a wide energy spectrum they enable the in situ examination of confined rock samples with thicknesses of 1 mm at a time resolution of order seconds hence fast kinetics with reaction completion times of about hundreds of seconds can be tracked with beam sizes of order tens to hundreds of micrometres it is possible to monitor multiple interrogation points in a sample with a lateral extent of a few centimetres thus resolving potential lateral spatial effects during dehydration and enlarging sample statistics significantly therefore the saxs waxs method offers the opportunity to acquire data on a striking range of length scales for rock samples with thicknesses of 10 3 m and widths of 10 2 m a lateral interrogation point spacing of 10 5 m can be achieved within each irradiated interrogation point volume information concerning pores with sizes between 10 9 and 10 7 m and the crystal lattice on the scale of 10 10 m is acquired in real time this article presents a summary of the physical principles underpinning transmission x ray scattering with the aim of providing a guide for the design and interpretation of time resolved saxs waxs experiments it is elucidated 1 when and how saxs data can be used to analyse total porosity internal surface area and pore size distributions in rocks on length scales from 1 to 300 nm 2 how waxs can be employed to track lattice transformations in situ and 3 which limitations and complicating factors should be considered during experimental design data analysis and interpretation to illustrate the key capabilities of the saxs waxs method we present a series of dehydration experiments on a well studied natural gypsum rock volterra alabaster our results demonstrate that saxs waxs is excellently suited for the in situ tracking of dehydration kinetics and the associated evolution of nano pores the phase transformation from gypsum to bassanite is correlated directly with nano void growth on length scales between 1 and 11 nm for the first time a comparison of the saxs waxs kinetic results with literature data emphasises the need for future dehydration experiments on rock specimens because of the impact of rock fabric and the generally heterogeneous and transient nature of dehydration reactions in nature it is anticipated that the saxs waxs method combined with in situ loading cells will constitute an invaluable tool in the ongoing quest for understanding dehydration and other mineral replacement reactions in rocks quantitatively

architecture and paleogeography of the early paleozoic carbonate systems in the east central tarim basin china constraints from seismic and well data abstract the evolution of the cambrian middle ordovician carbonate systems in the east central tarim basin northwestern china has been investigated using 2d seismic profiles and well data interpretation was performed on seismic profiles flattened along an originally horizontal surface base of the cambrian to remove the effects of post depositional deformations six seismic facies differently arranged in six seismic stratigraphic units record four major stages of architectural evolution from ramp to flat topped systems with differences from north to south 1 the onset of a homoclinal ramp over a clayey unit at the beginning of early cambrian 2 the development of a prograding carbonate platform characterized by restricted evaporitic facies in the inner platform domain during early cambrian to late cambrian 3 the development of a first prograding and a aggrading retrograding to the north platform during lower ordovician 4 the development of a prograding retrograding to aggrading final platform during middle ordovician the basinward eastward progradation of the carbonate platform edge has been reconstructed in time steps highlighting differences from the north to the south of the study area in terms of amount of progradation platform to basin relief and depositional surfaces likely controlled by differences in subsidence and environmental factors the identification of the four major stages in the evolution of the lower paleozoic succession of the tarim basin was likely controlled by changes in the rate of creation destruction of accommodation space due to the interplay between eustatic changes and tectonic events the demise of the cambrian to middle ordovician carbonate system in the study area is associated with a major tectonic event recorded by a tilting of the succession toward the east onlapped by sediments coming from the east and an uplift bulge of the western part of the study area

pore characterization of lower silurian shale gas reservoirs in the middle yangtze region central china abstract organic rich shales from lower silurian are widely distributed in the middle yangtze region central china however the lack of fundamental data for shale gas reservoirs increases the difficulty of gas exploration in this study 34 core samples were collected to characterize the shale pore structure and conduct a preliminary evaluation of the shale gas reservoir the toc total organic carbon content of the successively deposited black shales range from 1 6 to 5 9 while the total porosity range from 0 5 to 4 2 the positive correlation between toc and porosity indicates that toc is the key factor determining porosity the major component of the mineral matrix is quartz content of 21 4 69 2 followed by clay minerals content of 16 7 44 5 field emission scanning electron microscopy fe sem and energy dispersive x ray spectroscopy eds results illustrate that organic matter mixed with clay minerals can form an organo clay complex containing many nanopores furthermore larger organic pores are developed in organo clay complexes with higher clay content than in those with lower clay content correlational analyses between pore volume or pore surface area and toc or clay content demonstrate that micropores are associated with organic matter while mesopores and macropores are probably associated with clay minerals many of the clay related nanopores are organic in nature and are developed in organo clay complexes containing both organic matter and clay minerals overall the toc content controls development of nanopores in the shale pore structure followed by clay content the dft derived psd indicates that the pore volume is comprised primarily of pores having widths larger than 10 nm while the surface area is comprised primarily of micropores when considering the gas in place model and mechanisms of shale gas storage further shale gas exploration in central china should aim to the deep 1000 m and well preserved longmaxi shales

spectrum of pore types and networks in the deep cambrian to lower ordovician dolostones in tarim basin china abstract the complex tectonic activities and multi stage diagenetic modifications lead to the formation of a heterogeneous pore network spectrum ranging from macropores centimeter size to nanometer size pores three types of matrix dolomites dolomicrite microbial dolomite and crystalline dolomites and two types of dolomite cements saddle dolomite or crystalline dolomites are recognized in the cambrian to lower ordovician dolostones the pore systems include open vugs enlarged dissolution pores fabric dissolution pores intercrystal dissolution pores micro fractures as well as intracrystal pores forming dual or multiple pore networks the nmr t2 spectra are mainly characterized by bi modal distributions and mostly right skewed the very low t2 components 1000 ms represent the vuggy pores with pore sizes spanning from hundreds of m to thousands of microns the transition zones 100 ms

quantitative evaluation of potential organic matter porosity and hydrocarbon generation and expulsion from mudstone in continental lake basins a case study of dongying sag eastern china abstract this study presents approaches for evaluating potential organic matter porosity and hydrocarbon generation and expulsion in mudstone with strong heterogeneity in organic matter distribution in different evolution conditions of continental lake basins a total of 274 samples from the paleogene system at depth of 2770 3376 m of the niu 38 well in dongying depression eastern china were analyzed based on rock eval pyrolysis to investigate the corresponding potentials of organic matter porosity and hydrocarbon generation and expulsion the study shows that organic matter type controls hydrocarbon generation and expulsion potential in the continental lake basin strong heterogeneity was observed in the total organic carbon distribution among different organic matter types thus leading to significant gaps in hydrocarbon generation and expulsion potential type i organic matter exhibits high hydrocarbon generation and expulsion potential which is distributed within 24 07 105 79 mg g rock generation and 6 67 74 32 mg g rock expulsion with an average of 44 2 mg g rock and 18 91 mg g rock respectively types iii and ii 2 organic matter exhibit limited hydrocarbon generation and expulsion potential particularly type iii the hydrocarbon generation and expulsion potential of types iii and ii 2 organic matter is only distribute within 0 67 2 67 mg g rock generation and 0 32 1 20 mg g rock expulsion respectively thus indicating that these types are basically inert organic matter results show that type i organic matter with an initial total organic carbon content ranging from 6 28 to 22 0 can generate potential organic matter porosity varying from 4 15 to 26 21 capability to generate potential organic matter porosity decreases significantly from type i to types ii 1 ii 2 and iii organic matter initial total organic carbon is only within the range of 0 76 1 47 and potential organic matter porosity is between 0 10 and 0 41 for type iii organic matter the result shows that the potential organic matter pores generated by different organic matter types exhibit considerable differences between the samples in the continental lake basin the described methodology in this work allows a higher resolution in the evaluation on the heterogeneity of hydrocarbon source rock in vertical sequence thus it is an important way in the evaluation of potential source rock in the early exploration of unconventional oil and gas resources in the mudstone

nutrients in atmospheric aerosol particles along the atlantic meridional transect the atmosphere can be an important source of nutrients to remote ocean waters e g in supplying iron to nitrogen fixers in the tropical north atlantic we use results obtained from aerosol collection during four meridional transect cruises of the atlantic ocean in an attempt to identify sources of soluble nutrient species fe n p and si to the atlantic atmosphere the sahara desert was the dominant source of soluble aerosol fe and si and also a significant source of aerosol p biomass burning and another source possibly primary particles derived from vegetation also contribute to the aerosol p loading industrial nox and agricultural ammonium sources contribute to high nitrogen concentrations in the northern hemisphere while biomass burning appears to be a significant seasonal source of n to the southern hemisphere this work is an initial step in our aim to describe the atmospheric nutrient inputs to the atlantic basin using a much larger set of aerosol and rain samples that will be obtained during the atlantic meridional transect amt project and other field campaigns 2006 elsevier ltd all rights reserved

the composition and its impact on the methane sorption of lacustrine shales from the upper triassic yanchang formation ordos basin china abstract the organic geochemistry mineralogy and methane sorption of lacustrine shales of the upper triassic yanchang formation collected from the south eastern ordos basin were investigated to characterize them and clarify the effects of shale composition on their sorbed gas capacity these yanchang shales have recently been selected as a target area for shale gas exploration in typical terrestrial strata in china the two main sections of these shales containing type ii organic matters chang 7 and chang 9 have relatively high total organic carbon content toc of 2 10 the two shales also have similar mineralogies mainly comprising quartz clay minerals and feldspars both the chang 7 and chang 9 shales are generally in the oil window chang 9 is slightly more mature than chang 7 higher methane sorption capacity was observed for chang 9 than for chang 7 shales determined on a dried basis at 50 c methane sorption measurements were further performed on three samples from which the residual bitumen had been extracted and their corresponding kerogen fractions to gain insight into the effects of shale composition on methane sorption this was significantly higher in solvent extracted samples than in raw samples indicating that residual bitumen largely restricts methane sorption on such shales a positive correlation between the amount of clay minerals and methane sorption capacity of bulk rocks was evident suggesting that clay mineral content is relevant to methane sorption this result was also supported by the much higher methane sorption capacity of solvent extracted shales compared to the extracted kerogen from those shales when measured sorption data was normalized to toc values the effects of both residual bitumen and clay mineral on the methane sorption of bulk rocks have complicated the evaluation of methane sorption on organic matter in these mature shales

geochemistry and mineralogy of coal in the recently explored zhundong large coal field in the junggar basin xinjiang province china abstract the zhundong coalfield is a very large coal deposit currently under exploration and promises to be an important coal mining resource in western china the coal reserves amount to 164 gt at xiheishan and wucaiwan the coal bearing units are the badaowan lower jurassic and especially the xishanyao formations middle jurassic these contain from one to 31 coal seams one to 10 workable coals reaching the rank of high volatile a bituminous with an accumulated workable coal thickness of 20 87 m these recently explored coal reserves are of a high quality and are characterized by low ash aluminum iron sulfur and trace element contents the minerals present in this coal are mainly quartz kaolinite siderite and pyrite the trace element contents in both xiheishan and wucaiwan coals are much lower when compared with the usual concentration ranges present in chinese coals with the exception of ba and sr thus ba contents in xiheishan coal are higher than swaine s worldwide concentration range a large number of elements have mainly aluminosilicate affinity and occur in clay and other detrital coal minerals ca and mn have mainly carbonate affinity fe and s have mainly sulphide affinity in wuchaiwan coal in xiheishan fe mn and mg have mainly carbonate affinity siderite and probably b co ni and s have an organic affinity thus the zhundong coalfield contains coal with a very high quality and very low levels of impurities the very low ash yields s fe and trace element contents may be attributed to the sedimentological setting with intensive peat bog aggradation in a very shallow lake environment with a low detrital supply the very low sulfur content the relatively high ba sulfate barite content and the high siderite occurrence in xiheishan coal in contrast to the pyrite occurrence in wucaiwan coal may be attributed to the rapid aggradation of peat with the consequent oxidation and leaching of minerals elements and degradation of organic components under this scenario sulfate is trapped by the continuous precipitation and accumulation of barium sulfate very low soluble

pore connectivity and water accessibility in upper permian transitional shales southern china abstract pore connectivity of shale controls shale gas migration and production behavior the pore connectivity and water accessibility in clay rich upper permian transitional shales remain unclear contrast matching small angle neutron scattering cm sans tests were used to determine the accessibility of water to pores in the transitional shales complementary analyses with sans gas co2 and n2 physisorption isotherm mercury intrusion capillary pressure micp helium ion microscopy him as well as field emission scanning electron microscopy fe sem were conducted to study the pore connectivity and distribution characteristics of closed pores the results show that closed pores inaccessible to nitrogen molecules and mercury are mainly distributed in pore diameters 10 nm and associated with organic pores and interlayer spaces of illite smectite mixed layer mineral the pore volume values obtained from micp and n2 adsorption underestimate the large pores pore diameters 100 nm in shales based on deuterated water cm sans tests 87 98 of the pores 2 200 nm diameters are water connected in transitional samples the low accessibility to water is at pore sizes of 5 10 nm and 20 30 nm results from in situ gas contents show that closed pores have a certain gas bearing capacity but micropores pore diameters 2 nm control the gas occurrence in transitional samples the connectivity of the organic pore network and between organic pores and surrounding interparticle pores is directly supported by fe sem and him imaging overall improving pore fracture connectivity through effective fracturing techniques is a means of mitigating the rapid decline in shale gas production

mineralogy as a critical factor of dust iron solubility 1 to understand the impact of dust deposition on ocean primary productivity the evaluation of dust input is not sufficient and the soluble iron supply is also needed measurements of iron in aerosols suggest a much higher solubility than in soil implying substantial atmospheric processing of chemical or physical nature here we have investigated the effect of the mineralogy on iron solubility we have measured iron solubility from some minerals commonly found in dust clay feldspar and iron hydr oxides firstly we observe a greater solubility of iron resulting from clays 4 in comparison to iron hydr oxides 1 independently of specific surface of minerals secondly by considering amount of dissolved iron and the mineralogical composition of dust our results indicate that dissolved iron fraction mainly comes from clay dissolution in contrast to that assumed in some biogeochemical models in consequence it appears that iron solubility is closely linked to the mineralogical composition of aerosol

mineralogy and geochemistry of a superhigh organic sulfur coal yanshan coalfield yunnan china evidence for a volcanic ash component and influence by submarine exhalation abstract the mineralogy and geochemistry of a superhigh organic sulfur shos coal of late permian age from the yanshan coalfield yunnan province southwestern china have been studied using optical microscope low temperature ashing plus x ray diffraction analysis scanning electron microscope equipped with energy dispersive x ray spectrometer a sequential chemical extraction procedure and inductively coupled plasma mass spectrometry the m9 coal from the yanshan coalfield is a shos coal that has a total sulfur content of 10 12 11 30 and an organic sulfur content of 8 77 10 30 the minerals in the coal consist mainly of high temperature quartz sanidine albite muscovite illite pyrite and trace amounts of kaolinite plagioclase akermanite rutile and dawsonite as compared with ordinary worldwide bituminous coals and anthracite and chinese coals the m9 coal is remarkably enriched in b 268 g g f 841 g g v 567 g g cr 329 g g ni 73 9 g g mo 204 g g and u 153 g g in addition elements including se 25 2 g g zr 262 g g nb 20 1 g g cd 2 07 g g and tl 2 03 g g are also enriched in the coal occurrence of high temperature quartz sanidine muscovite and illite in the m9 coal is evidence that there is a volcanic ash component in the coal that was derived from acid volcanic ashes fallen into the swamp during peat accumulation occurrence of albite and dawsonite in the coal and strong enrichment of some elements including f s v cr ni mo and u are attributed to the influence by submarine exhalation which invaded along with seawater into the anoxic peat swamp abundances of lithophile elements including rare earth elements nb y zr and tio2 indicate that the silicate minerals in the coal were derived from the northern vietnam upland to the south of the basin

mineralogical and geochemical compositions of the pennsylvanian coal in the adaohai mine daqingshan coalfield inner mongolia china modes of occurrence and origin of diaspore gorceixite and ammonian illite abstract aluminum hydroxide boehmite rich pennsylvanian coals of high volatile a bituminous rank were found previously in the jungar coalfield inner mongolia china this paper reports new results on 48 bench samples of the cp2 coal from the adjacent adaohai mine daqingshan coalfield inner mongolia and provides new insights into the origin and modes of occurrence of the minerals and elements present in the cp2 coal compared to the same coal in the adjacent mines the cp2 coal in the adaohai mine has a higher rank ro ran 1 58 which is attributed to igneous intrusions during the late jurassic and early cretaceous epochs the proportion of inertinite 35 3 in the coal is higher than that in other late paleozoic coals in northern china but lower than that in the jungar coals minerals in the cp2 coal include diaspore boehmite gorceixite calcite dolomite siderite clay minerals kaolinite and ammonian illite and trace amounts of anatase fluorapatite quartz and pyrite based on mineral proportions in the coal bench samples the cp2 coal may be divided into four zones i to iv from bottom to top the major mineral in zones i and iv is kaolinite zones ii and iii are mainly composed of ammonian illite diaspore boehmite gorceixite calcite dolomite and siderite diaspore boehmite and gorceixite forming materials were derived from oxidized bauxite in the weathered crust of the benxi formation in the sediment source region during peat accumulation however gorceixite may have formed earlier than diaspore the diaspore was derived from gibbsite that was subjected to dehydration by the heat of the igneous intrusions the ammonian illite may have been formed at a relatively high temperature by interaction of kaolinite with nitrogen released from the organic matter in the coal during metamorphism caused by the igneous intrusion the calcite and dolomite occur as epigenetic cell and fracture fillings and were probably derived from the igneous fluids compared to the common chinese and world coals the cp2 coal is enriched in cao 1 69 mgo 0 32 p2o5 0 214 f 207 g g ga 16 3 g g zr 446 g g ba 276 g g hg 0 33 g g and th 12 4 g g but has a lower sio2 al2o3 ratio due to the higher proportions of diaspore boehmite and gorceixite in the coal the f occurs mainly in gorceixite and fluorapatite the major carriers of ga are diaspore and kaolinite but not gorceixite barium mainly occurs in gorceixite and barite mercury was probably derived from the igneous intrusion and is distributed in both the organic matter and the minerals the elements are classified into five associations by cluster analysis groups a b c d and e group a represents a ree be y se ga ge sc in pb bi nb ta tio2 w hg sb zr hf th u association most of the elements in group a are lithophile elements that occur in aluminosilicate minerals group b sn te zn cd v as cr cu mo ni re is weakly correlated with ash yield and is associated with unidentified trace sulfide minerals elements in group c ad na2o al2o3 sio2 li k2o rb cs tl association probably occur in the clay minerals and diaspore group d consists of p2o5 ba f sr s and cl and with the exception of s they occur in minerals gorceixite and fluorapatite oxides of fe2o3 mno cao mgo make up group e and mainly occur in the carbonate minerals the coals are enriched in light rees and the lrees hrees have been highly fractionated with an average la yb n of 8 71 the heavy rees in the coals have a stronger organic affinity than the lrees

facies architecture and high resolution sequence stratigraphy of an upper cretaceous platform margin succession southern central pyrenees spain abstract excellent exposures of upper cretaceous santonian carbonate platforms on the northern flank of sant corneli anticline southern central pyrenees provide detailed information of facies architecture in both depositional strike and dip directions basic accretional units are differentiated by facies contrast across mappable surfaces these surfaces do not show clear evidence of subaerial erosion and are correlated basinward with bedding planes across which there are subtle changes in skeletal composition two types of basic accretional units have been identified based on bedding patterns internal facies architecture and skeletal composition 1 rudist buildups consist of a rudist and coral belt at the platform margin passing landward into a slender hippuritid lithosome locally overlain by a bioclastic blanket that passes basinward into bioclastic apron like clinobeds and into fine grained packstone wackestone 2 calcarenite wedges consist of yellow brown benthic foraminifer rich grainstones to grain dominated packstones with scattered rudist shells and small coral colonies passing basinward into mud dominated packstones to wackestones with variable siliciclastic content quartz sand to silt and clay rudist buildups and calcarenite wedges alternate although not rhythmically these changes in platform skeletal composition reflect changes in the dominant type of carbonate producing biota independently of the changes in accommodation both types of basic accretional units rudist buildups and calcarenite wedges form simple sequences and parasequences according to internal lithofacies arrangement and inferred sea level cyclicity cycles or paracycles high frequency sea level cyclicity fits in the milankovitch frequency band long term changes in accommodation governing aggradation progradation and backstepping of basic sequences and parasequences reflect tectonic influence rather than long term changes in eustatic sea level

petrology mineralogy and geochemistry of submarine coals and petrified forest in the sozopol bay bulgaria abstract the mineralogy petrology and geochemistry of submarine coals and petrified tree trunks from the sozopol bay were investigated the coals are lignites of lower middle miocene age the petrified trunks are 40 cm up to 2 m high some of which are in growth position and others are fallen the main minerals in the coal are silicates of detrital origin clay minerals and authigenic pyrite authigenic sulfur and amber are present as well in the sozopol coals stored for 30 years a neoformed mineral assemblage comprising mainly of gypsum iron sulfates sulfates of varying fe na al k and mg content and halite has been observed the formation of the sulfates was induced by bacterial activity as well germanium li rb ti v mo cr mn co and ni are enriched in the coals as compared with the clarke values of the world brown coals in most of the samples studied the contents of ga b y w cu zn pb p and zr are elevated as well the element distribution is influenced by the lithotype composition most elements have a mixed mode of occurrence germanium v ti cr b na and ni and to a lesser extent sr and cu are organically associated while k li rb and fe have a distinct inorganic mode of occurrence molybdenum follows strictly the fe distribution it is suggested that the main sources of the trace elements were the volcanic rocks in the sediment source area from which the elements were leached in the peat bog

controls on boron and germanium distribution in the low sulfur amos coal bed western kentucky coalfield usa abstract the duckmantian aged amos coal bed is a thin geochemical analysis of the amos coal bed shows higher concentrations of b and ge than other western kentucky coal beds high total b concentrations as well as high b be both considered to be indicators of marine environments increase toward the top of the coal bed most of the b values for the amos samples range from 66 to 103 ppm whole coal basis indicating deposition in a brackish environment high ge concentrations in coals have been considered to be a function of seam thickness and proximity to the top and bottom of the coal bed thin coals such as the amos are dominated by the coal bed margins and therefore have a tendency to have relatively high ge concentrations in the case of the amos coal bed the lower bench has a higher ge content suggesting that the substrate was a more important source of ge than the roof rock

geochemistry of sulfur and elements in coals from the antaibao surface mine pingshuo shanxi province china abstract coal bearing strata in the antaibao surface mine pingshuo mining district shanxi china occur in the taiyuan formation upper carboniferous and shanxi formation lower permian the most productive coal seams in the mine are the nos 11 9 and 4 twenty five samples of coals partings and roof shales from the nos 11 10 9 5 taiyuan formation and 4 shanxi formation seams in the antaibao mine were analyzed for ash and total sulfur contents and forms of sulfur the no 11 seam is a medium to high sulfur coal 1 3 3 1 s a coal sample 14 1 ash from the no 10 seam contains 3 4 and high ash coal 37 4 ash from the same seam contains only 0 4 total sulfur the no 9 seam is a low to medium sulfur coal 0 6 1 3 s the highest sulfur content among the samples is 5 8 total sulfur from a coal sample of the no 5 seam the no 4 seam is low sulfur coal 0 29 0 54 s the remarkable variation in sulfur content among the coal seams in the taiyuan and shanxi formations could reflect different depositional environments from coastal to lower deltaic plain for the taiyuan and from upper deltaic plain to fluvial basin for the shanxi formation the sulfate sulfur comes mainly from the oxidation of pyrite sixteen samples were analyzed for 26 major minor and trace elements by x ray fluorescence spectrometry the sr content is significantly higher in coals from the no 4 seam in the shanxi formation than those from nos 11 to 5 seams chlorine sr ca and p are elements bound organically while si al ti fe k na mg cr v ni rb ba and nb are mainly associated with minerals

ocean chemistry a matter of mineralogy iron can stimulate productivity in many regions of the world ocean but only if it exists in a readily dissolvable form chemical analyses of typical aerosol particles show that the mineralogy of iron containing particles largely determines their solubility

nanominerals and ultrafine particles in sublimates from the ruth mullins coal fire perry county eastern kentucky usa abstract mineral sublimates from the ruth mullins fire in abandoned underground and surface mines in the high volatile a bituminous middle pennsylvanian hazard no 7 coalbed perry county kentucky were examined by optical mineralogy x ray diffraction xrd and high resolution transmission electron microscopy hr tem optical examination revealed the presence of salammoniac and a fine unidentified fibrous mineral xrd also showed the presence of salammoniac along with trace amounts of quartz kaolinite and possibly phengite both cubic and dendritic salammoniac forms were observed with hr tem gypsum jarosite with cubic pseudomorphs after pyrite and fe minerals including cr bearing hematite in association with jarosite were observed with hr tem dehydration of jarosite can lead to the formation of less hydrous fe sulfates and hematite

permeability distribution and scaling in multi stages carbonate damage zones insight from strike slip fault zones in the tarim basin nw china abstract architecture and permeability of fault damage zones are important for understanding faulting mechanisms and fluid flow in fractured rocks nevertheless this understanding is often hindered by limited availability of data especially in the subsurface a comprehensive suite of cores logs and production data is here presented to unravel petrophysical properties and fracture characteristics of deep 6000 m ordovician limestones within strike slip fault zones of the tarim intracratonic basin nw china the results show that 1 the carbonate porosity is mainly secondary dissolution porosity and comprises low porosity 5 md and high porosity 8 2 fault damage zones are generally tight with fracture aperture

sedimentation on a lower jurassic carbonate platform flank geometry sediment fabric and related depositional structures djebel bou dahar high atlas morocco abstract along the southern margin of the high atlas morocco carbonate platforms of lower jurassic age developed in a transtensional basin the south atlas trough complete exposure and preservation of the platform margin flank and basin of the djebel bou dahar allowed the subdivision of the slope into an upper mid and lower slope based on geometry sediment fabric and depositional structures at ca 50 m below the platform margin coral algal patch reefs and ooid sand shoals grade into the depositional slope the straight upper slope showing discontinuous bedding at angles up to 29 extends down to ca 250 m and consists mainly of poorly sorted mixtures of sand and gravel almost devoid of mud avalanching rockfall and shearing of the coarse gravelly sediment are the dominant processes readjusting the upper slope the middle and lower part of the slope profile extending down to ca 500 m below the margin is separated from the upper slope by a distinct slope break slope angles range from 19 near the slope break down to 4 8 where the slope merges with the basin plain the irregularly bedded mid slope is characterized by scouring and deposition of muddy sands and non cohesive gravelly debris flows sedimentation on the dominantly muddy concave upwards lower slope can be separated into evenly bedded shales muddy sands and mud free gravel sand mixtures deposited as debris sheets the results of this study emphasize the relationship between sediment fabric and the slope geometry of a carbonate platform flank the overall geometry internal heterogeneity and depositional structures are suggested to be strongly related to the original character of the sediment supplied to the djebel bou dahar platform flank

platform margins reef facies and microbial carbonates a comparison of devonian reef complexes in the canning basin western australia and the guilin region south china devonian reef complexes were well developed in western australia and south china but no detailed direct comparison has been made between reef building in the two regions the regions differ in several respects including tectonic stratigraphic and palaeoceanographic palaeogeographic settings and the reef building styles reflect minor differences in reef builders and reef facies similarities and differences between the two reef complexes provide insights into the characteristics of platform margins reef facies and microbial carbonates of both regions here we present a comparison of platform margin types from different stratigraphic positions in the late devonian reef complex of the canning basin western australia and middle and late devonian margin to marginal slope successions in guilin south china comparisons are integrated into a review of the reefal stratigraphy of both regions reef facies reef complex architecture temporal reef builder associations 2nd order stratigraphy and platform cyclicity in the two regions were generally similar where the successions overlap temporally however carbonate deposition began earlier in south china carbonate complexes were also more widespread in south china and represent a thicker succession overall platforms in the canning basin grew directly on precambrian crystalline basement or early palaeozoic sedimentary rocks but in south china carbonate complexes developed conformably on older devonian siliciclastic strata pre frasnian reef facies in south china had more abundant skeletal frameworks than in canning basin reefs of equivalent age and famennian shoaling margins containing various microbial reefs may have been more common and probably more diverse in south china however late devonian platform margin types have been documented more completely in the canning basin deep intra platform troughs deep depressions containing non carbonate pelagic sediments nandan type successions that developed along syndepositional faults characterize devonian carbonate platforms in south china but have no equivalent on the lennard shelf canning basin where inter reef areas were more shallow the south china platform to depression pattern was generally continuous from the lower to upper devonian indicating that many pre devonian tectonic features continued to exercise considerable effect through deposition localized fault controlled subsidence was an important factor in both regions but similarities in 2nd order aggradation progradation cycles suggest that eustasy was also an important control on the larger scale stratigraphic development of both regions

pore structure characteristics of lower silurian shales in the southern sichuan basin china insights to pore development and gas storage mechanism abstract silurian shale in sichuan basin is currently the most important target zone for shale gas exploration and development in china pore structure characteristics of lower silurian longmaxi shales from southern sichuan basin were investigated the combination of field emission scanning electron microscope fe sem and argon ion beam milling was utilized to describe the nanometer to micrometer scale 1 2 nm pore systems the shales were characterized by organic geochemical and mineralogical analyses total porosity pore size distribution psd specific surface area and gas content were determined controls of organic matter richness thermal maturity and mineralogy on porosity were examined the contribution of individual mineral components to total porosity was analyzed quantitatively total gas contents of the shales determined from canister desorption data were compared with theoretical sorptive and volumetric gas storage capacities the total organic carbon toc content of the shale samples ranges between 0 1 and 8 0 wt and helium porosity varies between 0 7 and 5 7 maturity in terms of equivalent vitrinite reflectance of bitumen reqv ranges from 1 8 to 3 2 toc content is a strong control for the pore system of these shales and shows a positive correlation with porosity porosity increases with increasing thermal maturity when reqv is less than 2 5 but decreases for higher thermal maturity samples fe sem reveals four pore types related to the rock matrix that are classified as follows organic matter om hosted pores pores in clay minerals pores of framework minerals and intragranular pores in microfossils pores in clay minerals are always associated with the framework of clay flakes and develop around rigid mineral grains because the pressure shadows of mineral grains prevent pores from collapsing pores of framework minerals are probably related to dissolution by acidic fluids and the dissolution related pores promote porosity of shales a unimodal psd exists in the micropore range of toc rich samples while the psd of carbonate rich samples are bimodal a psd maximum in the micropore range is attributed by om and another maximum in the range of mesopore macropores is probably caused by the dissolution of carbonate minerals quantitative evaluation of the contribution of individual mineral components to porosity shows that the organic matter contributes approximately 62 to the total porosity framework minerals quartz feldspar and carbonates et al and clay minerals contribute 25 and 13 respectively the total gas content of these shales ranges from 0 4 to 6 2 m3 t and the total gas contents of selected samples determined from canister desorption tests agree with the theoretically estimated original gas in place ogip om hosted pores are the main space for gas storage and accounted for about 78 55 adsorbed gas plus 23 free gas of the ogip while pores in the inorganic matter accommodate 22 free gas of the ogip

geochemical and mineralogical anomalies of the late permian coal in the zhijin coalfield of southwest china and their volcanic origin abstract this paper describes the influence of volcanic ash on the concentrations and occurrences of associated elements in coal in the zhijin coalfield in western guizhou province china our studies reveal that the no 9 coal seam in the zhijin coalfield has very high content of fe 4 34 cu 369 90 g g u 49 6 g g mo 63 10 g g zn 33 97 g g and zr 841 80 g g the studies have also found that elements such as fe and cu do not occur as sulfides in this coal seam in sharp contrast to many other coal seams in china the geochemical and mineralogical anomalies of the coal seam are attributed to synsedimentary volcanic ash in addition to normal macerals and minerals in coal a volcanic influenced material vim derived from volcanic ash detrital material of terrigenous origin and organic matter was identified under polarized light reflectance microscopy and scanning electron microscopy equipped with energy dispersive x ray edx analyzer the volcanic influenced material is the main carrier of the above elements in this coal six types of the volcanic influenced material vim 1 vim 2 vim 3 vim 4 vim 5 and vim 6 are further distinguished on the basis of their structures and compositions to the best of our knowledge this is the first report that presents a detailed classification of coal components with a high content of volcanic ash

pore characterization of organic rich lower cambrian shales in qiannan depression of guizhou province southwestern china abstract nine organic rich shale samples of lower cambrian black shales were collected from a recently drilled well in the qiannan depression guizhou province where they are widely distributed with shallower burial depth than in sichuan basin and their geochemistry and pore characterization were investigated the results show that the lower cambrian shales in qiannan depression are organic rich with toc content ranging from 2 81 to 12 9 thermally overmature with equivalent vitrinite reflectance values in the range of 2 92 3 25 and clay contents are high and range from 32 4 to 53 2 the samples have a total helium porosity ranging from 2 46 to 4 13 and total surface area in the range of 9 08 37 19 m2 g the estimated porosity in organic matters defined as the ratio of organic pores to the volume of total organic matters based on the plot of toc vs helium porosity is about 10 for the lower cambrian shales in qiannan depression and is far lower than that of the lower silurian shales 36 in and around sichan basin this indicates that either the organic pores in the lower cambrian shale samples have been more severely compacted than or they did not develop organic pores as abundantly as the lower silurian shales our studies also reveal that the micropore volumes determined by dubinin radushkevich dr equation is usually overestimated and this overestimation is closely related to the non micropore surface area of shales i e the surface area of meso and macro pores however the modified bet equation can remove this overestimation and be conveniently used to evaluate the micropore volumes surface area and the non micropore surface areas of micropore rich shales

composition and mode of occurrence of mineral matter in some colombian coals abstract the minerals in a range of colombian coal samples selected to represent the principal coal mining regions have been investigated using low temperature ashing and quantitative x ray diffraction techniques and the results compared to information from chemical analysis and mossbauer spectroscopy studies kaolinite illite interstratified illite smectite and quartz are the dominant mineral matter components in almost all of the coal samples with small but significant proportions of pyrite up to around 15 of the mineral matter being present in around half of the samples studied other minerals present in particular samples include chlorite muscovite paragonite ankerite dolomite calcite and siderite along with phosphate minerals apatite and goyazite jarosite and coquimbite are also noted in some of the pyrite bearing coals probably representing oxidation products of the pyrite developed with exposure or storage bassanite is present in the low temperature ash of some coals and in one sample occurs along with significant concentrations of hexahydrite alunogen tschermigite and paraluminite all of which were probably derived from interaction of inorganic elements in the organic matter with organic sulphur during maceral oxidation quantitative analysis of the minerals in the low temperature ash of the coal samples using rietveld based x ray diffraction techniques provides results that are consistent at least for the most abundant elements with the chemical composition of the coal ash as determined by standard analysis procedures the evaluation of mineral rich concentrates by mossbauer spectroscopy also provides results consistent with the xrd data especially as regards pyrite and some of the sulphate components optical microscopy indicates that much of the pyrite and in some cases also the carbonates occurs as anhedral crystals finely disseminated in the maceral components as aggregates of crystals including pyrite framboids as fine grained crystals replacing liptinite and as fracture fillings some sub angular to rounded quartz grains are also present possibly of detrital origin but most other minerals including the clay minerals occur mainly as aggregates of intimately admixed mineral and maceral constituents

significance of analytical particle size in low pressure n2 and co2 adsorption of coal and shale abstract this study examines the influence of analytical particle size on the surface area and mesopore and micropore volume data obtained from low pressure n 2 and co 2 adsorption analyses in response to the crushing of coal and shale pennsylvanian high volatile bituminous coal r o 0 57 and devonian to lower mississippian low maturity r o 0 57 and high maturity r o 1 30 shales from the illinois basin were progressively crushed from chunks 7 mm to 4 mesh 2 and co 2 adsorption analyses were performed on all the grain size fractions our results demonstrate that the values of both surface area and specific mesopore and micropore change with progressive crushing for example bet surface area of coal shows a steady increase from 2 m 2 g in the 4 mesh fraction to 4 7 m 2 g in the 200 mesh fraction for comparable size ranges bet surface area changes from 0 15 to 7 82 m 2 g in the low maturity shale and from 0 02 to 6 26 m 2 g in the high maturity shale changes in mesoporosity and microporosity parameters indicate that the coarsest fractions 4 mesh and larger are not suitable for low pressure adsorption analysis the values are very low and not reproducible dominantly because of equilibration problems our results demonstrate that the 60 mesh fraction for coal and the 200 mesh fraction for shales seem to be optimal and the most practical sizes for performing low pressure n 2 and co 2 adsorption analysis these analytical particle sizes yield results closest to the real values unbiased by disequilibrium

organic petrographical mineralogical and geochemical features of the achlada and mavropigi lignite deposits nw macedonia greece abstract the achlada and mavropigi lignite deposits in northern greece provide the main coal source for the next generation of greek power plants a comparative characterization of these two lignite deposits is presented covering the coal rank and the features of the maceral components based on detailed coal petrography and the mineralogical and geochemical features of the coals and their ashes based on xrf and xrd analyses the data are used to interpret the palaeoenvironments of the lignite beds as well as factors that may affect their burnout behavior both deposits have a lignite c rank the mavropigi lignite is mainly a matrix lignite lithotype whereas the achlada deposit consists both of matrix and xylite rich lithotypes the achlada lignite was formed in a fluviatile environment mainly in the abandoned channels of a meandering river system during flooding periods hence it is enriched in inorganic matter with ash values 30 wt the mavropigi lignite formed in a reed marsh environment under limno telmatic conditions and displays ash values the inorganic matter of the two deposits is different in composition due to the contrasting environments and these differences should be taken into account in optimizing their utilization for power production a preliminary assessment indicates that the achlada lignite may have more favorable slagging and fouling properties than the mavropigi lignite although experimental studies are required for more solid conclusions to be reached

pore structure and fractal analysis of lower carboniferous carbonate reservoirs in the marsel area chu sarysu basin abstract evaluation of carbonate heterogeneity closely related to pore geometry and connectivity is important in oil and gas field production and reservoir prediction to profoundly understand the heterogeneity of lower carboniferous carbonate reservoirs in the marsel area including visean c1v and serpukhovian c1sr the pore structure and fractal characteristics are investigated using routine petrophysical measurements x ray diffraction xrd cast thin section analysis scanning electron microscopy sem and mercury injection capillary pressure micp tests the origin of potentially prolific reservoir the relationships between fractal dimension and reservoir physical properties mineral composition and pore structure are also discussed xrd results reveal that the mineral compositions are highly heterogeneous in c1v and c1sr routine petrophysical experiments indicate that c1v and c1sr are generally tight however some high porosity permeability zones exist in c1sr which is described as a potentially prolific reservoir the cast thin section and sem analyses identify three main pore types in the potentially prolific reservoir interparticle dissolution pores intercrystalline dissolution pores and moldic pores the micp data reflect that the pore throat radii in the prolific reservoir range from 0 29 to 4 6 m whereas those in tight section are typically