Opencast coal mining produces trash of soil and rock containing various minerals,that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drain...Opencast coal mining produces trash of soil and rock containing various minerals,that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage(AMD)through oxidation pyrite minerals.The current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of India.In order to have a comprehensive overview of the AMD problem in Makum coalfield,the physico-chemical,geochemical,and petrological characteristics of the coal and overburden(OB)samples collected from the Makum coalfield(Northeast India)were thoroughly investigated.The maceral compositions reveal that coal features all three groups of macerals(liptinite,vitrinite,and inertinite),with a high concentration of liptinite indicating the coal of perhydrous,thereby rendering it more reactive.Pyrite(FeS_(2))oxidation kinetics were studied by conducting the aqueous leaching experiments of coal and(OB)samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods,and to replicate the actual mine site leaching.Inductively coupled plasma-optical emission spectroscopy(ICP-OES)was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching experiment.The Rare earth element(REE)enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and OB.These experiments reveal the change in conductivity,acid producing tendency,total dissolved solid(TDS),total Iron(Fe)and dissolved Sulfate(SO_(4)^(2−))ions on progress of the leaching experiments.Moreover,the discharge of FeS_(2) via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order kinetics.A bio-remediative strategies is also reported in this paper to mitigate AMD water by employing size-segregated powdered limestone and water hyacinth plant in an indigenously developed site-specific prototype station.Apart from neutralisation of AMD water,this eco-friendly AMD remediation strategy demonstrates a reduction in PHEs concentrations in the treated AMD water.展开更多
Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of t...Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of the Sinian Chengjiang Formation (Zac). It is dominated by pyroxenites and can be roughly divided into four lithofacies zones, namely gabbros at the outermost periphery and fine-, medium-, and coarse-grained pyroxenites from margin to center. With the transition from pyroxenites to gabbros, the Shuikou rock mass features gradual enrichment in silica and alkali overall, an increase in ΣREE and (La/Yb)<sub>N</sub> ratio, and a decrease in δEu values and Eu/Sm ratio, indicating that the Shuikou rock mass was formed from the continuous differentiation and crystallization of consanguineous magma and that low-degree partial melting occurred meanwhile. According to the U-Pb baddeleyite geochronology, the crystallization age of the Shuikou rock mass is 210.7 ± 3 Ma (MSWD = 1.01). Based on this, as well as the analysis of geochemical characteristics, the Shuikou rock mass occurred in a continental intraplate tensional environment, this is closely related to the activities of the Emeishan mantle plume during the same period.展开更多
A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in the...A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in thecourse of the Caledonian-Indosinian ductilc and brittle-ductile reworking. The study on their petrography. va-riations in composition and conditions of formation is conducive to revealing the metamorphism-deformationhistory of the core of the Qinling orogenic belt and further to understanding the dynamic mechanism of its evo-lution.展开更多
The India-Asia collision and uplift of the Tibetan plateau are the most important geological events in Earth＇s history; it profoundly affects our understanding of global climate change during the Cenozoic. Despite a ...The India-Asia collision and uplift of the Tibetan plateau are the most important geological events in Earth＇s history; it profoundly affects our understanding of global climate change during the Cenozoic. Despite a research history over half a century, the uplifting history remains hotly controversial. The early uplifting model suggested that the Lhasa terrane attained an elevation of 3-4 km at -99 Ma due to the Lhasa-Qiangtang collision. However, the evidences are mainly from deformation of the Lhasa terrane and inconsistency with the palaeontological data.展开更多
Mansehra Granite(MG)is massive and sheared which contains light-gray to jet-black schistosed and light-gray micaceous quartzite restites.The later possess relatively higher quartz as compared with mica contents wherea...Mansehra Granite(MG)is massive and sheared which contains light-gray to jet-black schistosed and light-gray micaceous quartzite restites.The later possess relatively higher quartz as compared with mica contents whereas the former has predominant quartz and feldspar.Enclosure of apatite and zircon in micas and absence of sillimanite in schistosed and non-foliated facies suggest that these rocks are restite in nature.展开更多
The present communication aims at an assessment of the current status on petrological evolution of the Eastern Ghats Belt in the context of its correlation with three supercontinents,namely Columbia,Rodinia and East G...The present communication aims at an assessment of the current status on petrological evolution of the Eastern Ghats Belt in the context of its correlation with three supercontinents,namely Columbia,Rodinia and East Gondwana.Despite intensive research by different groups over the last three decades,various issues remain unresolved.Some major outstanding issues include,the nature of the basement for the Eastern Ghats rocks,isotopic and/or lithotectonic subdivisions of the belt,nature of the retrograde path of UHT metamorphism and timing of juxtaposition of the mobile belt with the adjacent cratons.展开更多
Reaction textures and fluid inclusions in the -2.0 Ga pyroxene-bearing dehydration zones within the Sand River biotite-hornblende orthogneisses （Central Zone of the Limpopo Complex） suggest that the formation of the...Reaction textures and fluid inclusions in the -2.0 Ga pyroxene-bearing dehydration zones within the Sand River biotite-hornblende orthogneisses （Central Zone of the Limpopo Complex） suggest that the formation of these zones is a result of close interplay between dehydration process along ductile shear zones triggered by H2O-CO2-salt fluids at 750--800 ℃ and 5.5--6.2 kbar, partial melting, and later exsolution of residual brine and H2O-CO2 fluids during melt crystallization at 650--700 ℃. These processes caused local variations of water and alkali activity in the fluids, resulting in various mineral assemblages within the dehydration zone. The petrological observations are substantiated by experiments on the interaction of the Sand River gneiss with the H2O-CO2-（K, Na）Cl fluids at 750 and 800 ℃ and 5.5 kbar. It follows that the interaction of biotite-amphibole gneiss with H2O-CO2-（K, Na）CI fluids is accompanied by partial melting at 750--800 ℃. Orthopyroxene-bearing assemblages are characteristic for temperature 800 ℃ and are stable in equilibrium with fluids with low salt concentrations, while salt-rich fluids produce clinopyroxene-bearing assemblages. These observations are in good agreement with the petrological data on the dehydration zones within the Sand River olthogneisses.展开更多
The influence of water is evaluated in this last contribution of a series aiming to study the petrological and dynamic evolution of mantle melting.Water is considered to be either a chemical component in the melt or s...The influence of water is evaluated in this last contribution of a series aiming to study the petrological and dynamic evolution of mantle melting.Water is considered to be either a chemical component in the melt or solid assemblage but it can also be present as a pure water phase in a oversaturated environment.A three-phase-flow model was developed for this purpose.Only a limited set of conditions has been applied to the 1-D upwelling mantle column.A range of fixed temperatures(1150-1450℃) and water contents in the solid mantle(0,0.02 wt.%,0.2 wt.%) have been imposed at the entry point(120 km deep) for the two melting models introduced in the previous installments,dynamic equilibrium melting(DEM) and dynamic fractional melting(DFM) model.As expected,for a given temperature at the base of the mantle column,the depth of the first melt formation increases with higher water content in the mantle.After the first melt is created,very negligible amount of melt is formed over a certain depth interval which approximately ends at the depth where the first melting of the dry mantle would take place.However melt is present as a dynamic phase thorough the entire region regardless whether the DEM or DFM model has been applied.Under a quasi-steady state regime,the melt and residual mantle compositions vary significantly over depth,depending on the conditions imposed to the model(DEM,DFM,bottom temperature and water content).Several distinctions can be made at the extraction point(top of the mantle column=15 km deep).For DEM and DFM models at this lowest depth,the most influential factor affecting the melt composition after the quasi-steady state condition has been reached is the temperature at the base of the column.In general,for a high temperature model,the input water in the mantle does not seem to play a significant role on the bulk composition of the melt(except for the water content in melt).But at low temperature water does have some noticeable influence on the variation of some chemical components in melt(SiO2,Fe2 O3,CaO,Na2 O at T=1250℃ or lower).A similar conclusion can be made also for the residual mantle composition.The presence of a dynamic free water phase is detected only in absence of melt or in coexistence with a melt phase when the mantle is relatively cold(bottom temperature≤1250℃) and the input water content at the base of the model is relatively high(0.2 wt.%).Complete output data for several numerical simulations and six animations illustrating various melting models are available following the instructions in the supplementary material.展开更多
The western Iratsu mass, the largest tectonic body in the Sambagawa metamorphic belt, central Shikoku, is mainly composed of epidote amphibolite with minor amounts of eclogite. Systematically, a majority of garnets sh...The western Iratsu mass, the largest tectonic body in the Sambagawa metamorphic belt, central Shikoku, is mainly composed of epidote amphibolite with minor amounts of eclogite. Systematically, a majority of garnets show bell-shaped chemical zoning of pyrope contents and Mg/(Mg+Fe2+) monotonously increasing outward. The grossular component in zonal garnet increases outwards, maximizes at an intermediate part, and then decreases towards the outermost rim, reflecting a process from increasing to decreasing pressure conditions during the prograde metamorphism. Jadeite contents of omphacite range from 25～20mole% within the cores to 15～10 mole% at the rims, implying a pressure-decreasing process (from 11 × 105 Pa to 8 × 105 Pa). The peak pressure-temperature (P-T) condition of 630～680 ℃ and ca. 15× 105 Pa in the western Iratsu mass is much higher than that of (610±25) ℃ and (10± 1)× 105 Pa of the Sambagawa oligoclase-biotite zone schists. The authors suggest a clockwise P-T-t path for the western Iratsu mass.展开更多
A K-rich volcano zone , Wudalianchi-Erkeshan - Keluo in Heilongjiang Province of Northeastern China , is studied in this paper . Some results from the study of mantle inclusions , accumulative inclusions and megacryst...A K-rich volcano zone , Wudalianchi-Erkeshan - Keluo in Heilongjiang Province of Northeastern China , is studied in this paper . Some results from the study of mantle inclusions , accumulative inclusions and megacrysts are reported here for the first time . On the petrological , experimental , and magma-dynamical study of the host rocks and their inclusions and megacrysts , it is concluded that the K-rich magma in these areas was derived from upper mantle with rich in K2O and incompatible element by partial melting of phlogopite-bearing Iherzolite. Leucite picrite magma is primary and the magma represented by leucite basalt is derivative one of both fractional crystallization and assimilation . The mantle where the magma came from had undergone both the depletion and enrichment events , and had high geotherm similar to that of mid -oceanic ridge and rift valley . Mantle metasomatism , uplift and diapirism result in the K-rich volcanic rocks . The environment of volcanism in these areas is rift tectonics within continental plate ,and the composition and distribution of volcanic rocks in these areas are controlled by mantle-reach faults , and are not directly related to the subduction of the Pacific plate .展开更多
The provenance of modern beach sands from the Barton and Weaver peninsulas of King George Island,South Shetland Islands,West Antarctica was investigated based on their modal composition and geochemical data.The source...The provenance of modern beach sands from the Barton and Weaver peninsulas of King George Island,South Shetland Islands,West Antarctica was investigated based on their modal composition and geochemical data.The source rocks and provenance tectonic setting are interpreted as volcanic and plutonic rocks formed in the magmatic arc setting.This interpretation is generally consistent with the currently distributed bedrocks in the ice-free areas and tectonic setting of King George Island.However,the composition of beach sands of the Barton and Weaver peninsulas is different from distribution of bedrocks exposed in the ice-free areas of both peninsulas.The present beach sands are interpreted as previous subaqueous moraines that were eroded and transported by advancing glaciers across the both peninsulas and deposited in front of the glacier grounding line.In other words,sand sediments in the beaches of the two peninsulas were not derived from bedrocks currently exposed in ice-free areas,but it is interpreted that they were subaqueous moraines before deglaciation and were mixed with sediment derived from wave erosion of bedrocks and sediments of the paleoshoreline during the isostatic uplift of King George Island.Finally,they were reworked under the current beach environments.展开更多
NWA 16080 is a representative reduced CV carbonaceous chondrite(CV_(red)),consisting mainly of chon-drules(47 vol%)and matrix(42 vol%),along with minor quantities of calcium-and aluminum-rich inclusions(CAI)and amoebo...NWA 16080 is a representative reduced CV carbonaceous chondrite(CV_(red)),consisting mainly of chon-drules(47 vol%)and matrix(42 vol%),along with minor quantities of calcium-and aluminum-rich inclusions(CAI)and amoeboid olivine aggregates(AOA)(CAI+AOA,6 vol%)and opaque minerals(5 vol%).The chondrules exhibit well-preserved outlines and can be categorized into Type Ⅰ(Fa<10)and Type Ⅱ(Fa>10).They primarily consist of magnesium-rich olivine,along with both low-Ca and high-Ca pyroxenes,and contain minor amounts of secondary plagioclase.Olivines present in chondrules display compositional zoning characterized whereas the matrix is composed of fine-grained olivine.Nickel-rich metal and nickel-poor sulfides are also present,along with trace amounts of magnetite.In contrast to standard oxidized CV chondrites(CV_(ox)),the presence of high metal,Ni-poor sulfides,and reduced magnetite in NWA 16080 indicates a more reduced parent-body environment.Shock metamorphism is classified as mild(S1),while terrestrial weathering is characterized as low(W2).Raman spectroscopy indicates a diverse spectrum of organic matter(OM)maturity:certain areas exhibit characteristics akin to other CV_(red) chondrites,whereas others reach maturity levels comparable to those observed in CV_(ox) chondrites.The Raman parameters indicate that this meteorite is classified as approximately type 3.4 to 3.5.The overlapping OM maturity with certain CV_(ox) chondrites provides a contradiction to the anticipated depth-thermal layering outlined in the onion-shell model.This suggests that the CV parent body probably experienced more intricate processes,including impacts and fluid-rock interactions,rather than merely depth-dependent heating.展开更多
Mineralogical data are presented for the peridotite xenoliths from Miocene(~19 Ma)Qingyuan basalts in the eastern North China Craton(NCC),with the aim of constraining on property of the sub-continental lithospheric ma...Mineralogical data are presented for the peridotite xenoliths from Miocene(~19 Ma)Qingyuan basalts in the eastern North China Craton(NCC),with the aim of constraining on property of the sub-continental lithospheric mantle(SCLM)beneath the northern Tan-Lu fault zone(TLFZ)during the Cenozoic.The Qingyuan peridotites are dominated by spinel lherzolites with moderate-Mg^(#)olivines(89.4 to 91.2),suggesting that the regional SCLM is mainly transitional and fertile.Light rare earth element(LREE)-depleted,slightly depleted and enriched clinopyroxenes(Cpx)are identified in different peridotites.Chemical compositions of the LREE-enriched Cpx and the presence of phlogopite suggest that the Qingyuan SCLM has experienced silicate-related metasomatism.The synthesis of available mineral chemical data of the mantle xenoliths across the NCC confirms the SCLM beneath the NCC is highly heterogeneous in time and space.The Mesozoic–Cenozoic SCLM beneath the TLFZ and neighboring regions are more fertile and thinner than that beneath the region away from the fault zone.The fertile and refractory peridotite xenoliths experienced varying degrees of silicate and carbonatite metasomatism,respectively.The spatial-temporal lithospheric mantle heterogeneity in composition,age and thickness suggest that the trans-lithosphere fault zone played an important role in heterogeneous replacement of refractory cratonic lithospheric mantle.展开更多
1AIM AND SCOPE Geoscience Frontiers(GSF)publishes peer reviewed research articles and reviews in interdisciplinary fields of Earth and Planetary Sciences.GSF bridges innovative,provocative and challenging concepts and...1AIM AND SCOPE Geoscience Frontiers(GSF)publishes peer reviewed research articles and reviews in interdisciplinary fields of Earth and Planetary Sciences.GSF bridges innovative,provocative and challenging concepts and models related to various fields of research including petrology and geochemistry in understanding lithospheric architecture and mantle dynamics,global tectonics,economic geology and fuel exploration,geophysics,stratigraphy and paleontology with insights on correlations and evolution,environmental and engineering geology,astrogeology,nexus of resources-energy-emissions-climate under Sustainable Development Goals,among other themes.展开更多
Research into metamorphism plays a pivotal role in reconstructing the evolution of continent,particularly through the study of ancient rocks that are highly susceptible to metamorphic alterations due to multiple tecto...Research into metamorphism plays a pivotal role in reconstructing the evolution of continent,particularly through the study of ancient rocks that are highly susceptible to metamorphic alterations due to multiple tectonic activities.In the big data era,the establishment of new data platforms and the application of big data methods have become a focus for metamorphic rocks.Significant progress has been made in creating specialized databases,compiling comprehensive datasets,and utilizing data analytics to address complex scientific questions.However,many existing databases are inadequate in meeting the specific requirements of metamorphic research,resulting from a substantial amount of valuable data remaining uncollected.Therefore,constructing new databases that can cope with the development of the data era is necessary.This article provides an extensive review of existing databases related to metamorphic rocks and discusses data-driven studies in this.Accordingly,several crucial factors that need to be taken into consideration in the establishment of specialized metamorphic databases are identified,aiming to leverage data-driven applications to achieve broader scientific objectives in metamorphic research.展开更多
Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for decipherin...Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for deciphering the geodynamic processes in subduction zones.In this study,we apply different versions of datasets(ds55 and ds62)and associated a-x relations to a wellestablished LT-HP eclogite at Huwan in the classic western Dabie orogen to constrain its P-T evolution.The eclogite comprises garnet+omphacite+amphibole+white mica+epidote+quartz+chlorite+rutile/ilmenite/sphene.Garnet porphyroblasts show mono-variation in the end members(spessartine from 17 mol%to 0,pyrope from 2 mol%to 18 mol%,almandine from 47 mol%to 64mol%and grossular from 35 mol%to 18 mol%)from core to rim.Phase diagrams combined with compositional isopleth thermobarometry show that dataset ds62 and associated a-x relations yield P_(max)of~33 kbar at~560℃,conflicting with our petrological observations and previous studies.On the other hand,phase equilibrium modeling using dataset ds62 and a revised symmetric garnet a-x model irrespective of Fe^(3+)(O)gives P_(max)of~27 kbar at~560℃,consistent with the results using dataset ds55 and associated a-x relations.Therefore,we recommend a symmetric model for garnet involving py,alm,gr and spss,without Fe~(3+)components,instead of the asymmetric garnet a-x relations involving py,alm,gr,spss and kho by White et al.(2014),for calculating phase diagrams for LT-(U)HP eclogite when using dataset ds62.In this study,the defined P-T path is characterized by a segment of the prograde evolution showing a first moderate slope,followed by gentle then steep slopes,representing the thermal structure evolution recorded by slab surface during continental subduction.Our work combined with previous studies conclude that in western Dabie,the Huwan HP eclogite belt to the north and the Hong'an HP eclogite belt to the south belong to the same HP slice overlying the Xinxian UHP slice.展开更多
A-type rocks have drawn considerable attention in the past few decades due to their distinctive mineralogical and geochemical fingerprints and prospective utility for geodynamic reconstruction of the lithosphere.A com...A-type rocks have drawn considerable attention in the past few decades due to their distinctive mineralogical and geochemical fingerprints and prospective utility for geodynamic reconstruction of the lithosphere.A comprehensive study,involving zircon U-Pb geochronology,wholerock elemental and Sr-Nd-Pb isotopic geochemistry,was undertaken to elucidate the origin and evolutionary process for syenites from the Daguiping area in the North Daba mountains,South Qinling belt.The syenites revealed an Ordovician igneous crystallization age of 454.4±17 Ma,coeval with the neighboring mafic rocks.All samples show high SiO_(2),LREEs,and HFSEs(Nb,Ta,Zr and Hf)contents,with negative to slightly positive Eu(Eu/Eu^(*)=0.78-1.08)anomalies.The geochemical characteristics of the Daguiping syenites imply that they are of A_1-type magmatic affinity,which is confirmed by their high total alkali levels(8.57 wt.%-11.94 wt.%),Zr+Nb+Ce+Y contents(738.00 ppm-1734.78 ppm),and 10000×Ga/Al ratios(3.25-4.22),as well as low Y/Nb ratios(0.30-0.40).Our samples exhibit a wide range of initial^(87)Sr/^(86)Sr ratios of 0.701943 to 0.709802 and a narrow range of^(143)Nd/^(144)Nd ratios of 0.512205-0.512246 withε_(Nd)(t)values from+3.0 to+3.8.These rocks display(^(206)Pb/^(204)Pb)_(initial),(^(207)Pb/^(204)Pb)_(initial),and(^(208)Pb/^(204)Pb)_(initial)ratios range from 17.96 to 18.62,15.55 to 15.59,and 36.87 to 38.22,respectively.All of the isotopic data indicate that the syenites were essentially mantle-derived.A cogenetic source for the Daguiping syenites and coeval mafic rocks in the South Qinling belt is supported by their uniform Sr-Nd-Pb isotope data and linear major/trace elemental changes,with prolonged fractional crystallization considered as the essential mechanism for these geochemical discrepancies.Mass-balance and Rayleigh fractionation modeling estimate~85 vol%fractional crystallization involving amphibole,clinopyroxene,plagioclase,Kfeldspar,biotite,Fe-Ti oxide,and quartz,to reproduce the compositional varieties between a coeval mafic rock and the Daguiping syenites.The Daguiping syenites and associated alkaline rocks were likely related to a rifting episode triggered by asthenospheric upwelling,which led to the South Qinling detaching from the South China Block along the Mianlue suture during the Early Paleozoic.展开更多
Fluid-rock interaction plays a critical function in physical and chemical processes associated with the formation and evolution of oil and gas reservoir space.In the diagenetic stage of shallow burial,the dissolution ...Fluid-rock interaction plays a critical function in physical and chemical processes associated with the formation and evolution of oil and gas reservoir space.In the diagenetic stage of shallow burial,the dissolution of carbonate rocks by acidic fluids is conducive to the development of secondary pore space in reservoirs.In contrast,the free drift experiment based on water bath instrument can simulate the dissolution process of carbonate rocks in shallow burial environment effectively.In order to study the shallow burial dissolution mechanism of carbonate rocks in different acid solutions,14 samples of typical carbonate rocks of Sinian,Cambrian,Ordovician,Permian and Triassic ages in the Tarim and Sichuan basins,China were used.The dissolution experiments on carbonate rocks in sulfuric acid,acetic acid,hydrochloric acid,silicic acid and carbonic acid at shallow burial temperature(30℃≤T≤90℃)were carried out using a water bath instrument.The PHREEQC software was used to simulate the dissolution of carbonate minerals,in order to compare the results of constant temperature water bath experiment.The results show that acid solutions have significant dissolution effect on shallow burial carbonate rocks when T=50–60℃,which corresponds to the burial depth of 1500–2000 m in the Tarim Basin and 1110–1480 m in the Sichuan Basin.However,there were obvious differences in the dissolution and reformation of carbonate rocks in different acids.In particular,sulfuric acid solution produced by thermochemical sulfate reduction can significantly promote the dissolution of carbonate rocks,especially dolomitic limestone.Moreover,the dissolution of limestone reservoirs is stronger than that of dolomite reservoirs in shallow burial.The results will provide new insights into the study of dissolution laws and influencing factors of reservoir spaces and the evaluation and prediction of carbonate reservoirs in China.展开更多
The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in India.For over a decade,the exploration and extraction of hydrocarbons in these basins.Paleocene-Eocene age roc...The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in India.For over a decade,the exploration and extraction of hydrocarbons in these basins.Paleocene-Eocene age rocks bear organic-rich sediments in these basins,including lignite and carbonaceous shale deposits.The present research investigates the source rock properties,petroleum potential and thermal maturity of the carbonaceous shale partings from the lignite mines of Gurha(Bikaner-Nagaur Basin)and Kapurdi(Barmer Basin)using petrographical and geochemical tools.The carbonaceous shales have high organic matter(OM),with considerable total organic carbon(TOC)contents ranging from 13%to 39%.Furthermore,they contain hydrogen-rich kerogen,including types II and II/III,as evidenced by the Rock-Eval and elemental analysis results.The existence of these kerogen types indicates the abundance of reactive(vitrinite and liptinite)macerals.However,the carbonaceous shales from the Bikaner–Nagaur Basin have oil generation potentials,with a high hydrogen index(up to 516 mg HC/g TOC)and a H/C ratio(up to 1.5)along with a significant presence of oil-prone liptinitic macerals.Apart from the geochemical and petrological results,the studied shales have low huminite reflectance(0.31%–0.48%),maximum temperature(S_(2) peak;Tmax)between 419℃ and 429℃,and low production index values(PI:0.01–0.03).These results indicate that these carbonaceous shales contain immature OM,and thereby,they cannot yet release commercial amount of oil.This immaturity level in the studied outcrop section is due to the shallow burial depth.Geochemical proxies further indicate the presence of both oil and gas-prone source rocks.展开更多
Massive granitic rock avalanches are extensively developed in the middle section of the northern Qinling Mountains(NQM),China.The current consensus is that their formation could have been connected with seismic events...Massive granitic rock avalanches are extensively developed in the middle section of the northern Qinling Mountains(NQM),China.The current consensus is that their formation could have been connected with seismic events that occurred in the NQM.However,there is a lack of systematic discussion on the genetic dynamics of these rock avalanches.Hence,taking Earth system scientific research as a starting point,this paper systematically summarizes and discusses development characteristics,formation times and genetic dynamic mechanisms of granitic rock avalanches in the NQM based on geological investigations,high-precision remote sensing interpretations,geomorphological dating,geophysical exploration,and a large-scale shaking table model test.We identified 53 granitic rock avalanches in this area,with a single collapse area ranging from 0.01×10~6 to 1.71×10~6 m^(2).Their development time can be divided into six stages,namely,107000 years BP,11870–11950 years BP,11000 years BP,2300 years BP,1800 years BP,and 1500 years BP,which were closely related to multiple prehistoric or ancient earthquakes.We suggest that long-term coupling of internal and external earth dynamics was responsible for the granitic rock avalanches in the NQM;the internal dynamics were mainly related to subduction,collision and extrusion of different plates under the Qinling terrane,leading to the formation and tectonic uplift of the Qinling orogenic belt;and the external dynamics were closely associated with climate changes resulting in mountain denudation,freeze-thaw cycles and isostatic balance uplift.In this process,the formation and evolution of the Qinling orogenic belt play a geohazard-pregnant role,structural planes,including faults and joints,play a geohazard-controlled role,and earthquakes play a geohazard-induced role,which jointly results in the occurrence of large-scale granitic rock avalanches in the NQM.This research can not only decipher the genetic dynamic mechanism of large hard granitic rock avalanches but also reveal temporal and spatial patterns of the evolution of breeding and the generation of large-scale rock avalanches in the margins of orogenic belts.展开更多
文摘Opencast coal mining produces trash of soil and rock containing various minerals,that are usually dumped nearby the abandoned sites which causes severe environmental concern including the production of acid mine drainage(AMD)through oxidation pyrite minerals.The current study entailed assessing the potential production of AMD from an opencast coal mining region in Northeast part of India.In order to have a comprehensive overview of the AMD problem in Makum coalfield,the physico-chemical,geochemical,and petrological characteristics of the coal and overburden(OB)samples collected from the Makum coalfield(Northeast India)were thoroughly investigated.The maceral compositions reveal that coal features all three groups of macerals(liptinite,vitrinite,and inertinite),with a high concentration of liptinite indicating the coal of perhydrous,thereby rendering it more reactive.Pyrite(FeS_(2))oxidation kinetics were studied by conducting the aqueous leaching experiments of coal and(OB)samples to interpret the chemical weathering under controlled laboratory conditions of various temperature and time periods,and to replicate the actual mine site leaching.Inductively coupled plasma-optical emission spectroscopy(ICP-OES)was operated to detect the disposal of some precarious elements from coal and OB samples to the leachates during our controlled leaching experiment.The Rare earth element(REE)enrichment in the samples shows the anthropogenic incorporation of the REE in the coal and OB.These experiments reveal the change in conductivity,acid producing tendency,total dissolved solid(TDS),total Iron(Fe)and dissolved Sulfate(SO_(4)^(2−))ions on progress of the leaching experiments.Moreover,the discharge of FeS_(2) via atmospheric oxidation in laboratory condition undergoes a significant growth with the rise of temperature of the reaction systems in the environment and follows pseudo first order kinetics.A bio-remediative strategies is also reported in this paper to mitigate AMD water by employing size-segregated powdered limestone and water hyacinth plant in an indigenously developed site-specific prototype station.Apart from neutralisation of AMD water,this eco-friendly AMD remediation strategy demonstrates a reduction in PHEs concentrations in the treated AMD water.
文摘Geotectonically, the Shuikou ultrabasic-basic rock mass is located on the western margin of the Yangtze Platform. As revealed by field geological surveys, the Shuikou rock mass intrudes into the quartz sandstones of the Sinian Chengjiang Formation (Zac). It is dominated by pyroxenites and can be roughly divided into four lithofacies zones, namely gabbros at the outermost periphery and fine-, medium-, and coarse-grained pyroxenites from margin to center. With the transition from pyroxenites to gabbros, the Shuikou rock mass features gradual enrichment in silica and alkali overall, an increase in ΣREE and (La/Yb)<sub>N</sub> ratio, and a decrease in δEu values and Eu/Sm ratio, indicating that the Shuikou rock mass was formed from the continuous differentiation and crystallization of consanguineous magma and that low-degree partial melting occurred meanwhile. According to the U-Pb baddeleyite geochronology, the crystallization age of the Shuikou rock mass is 210.7 ± 3 Ma (MSWD = 1.01). Based on this, as well as the analysis of geochemical characteristics, the Shuikou rock mass occurred in a continental intraplate tensional environment, this is closely related to the activities of the Emeishan mantle plume during the same period.
文摘A series of ductile shear zones of the overthrust and strike-slip-types and related ductile shear metamorphicrocks, including tectonic melange and mylonites. were formed in the core of the Qinling orogenic belt in thecourse of the Caledonian-Indosinian ductilc and brittle-ductile reworking. The study on their petrography. va-riations in composition and conditions of formation is conducive to revealing the metamorphism-deformationhistory of the core of the Qinling orogenic belt and further to understanding the dynamic mechanism of its evo-lution.
基金financially supported by the National Natural Science Foundation of China(41572188)the China Geological Survey(DD20160159-06)
文摘The India-Asia collision and uplift of the Tibetan plateau are the most important geological events in Earth＇s history; it profoundly affects our understanding of global climate change during the Cenozoic. Despite a research history over half a century, the uplifting history remains hotly controversial. The early uplifting model suggested that the Lhasa terrane attained an elevation of 3-4 km at -99 Ma due to the Lhasa-Qiangtang collision. However, the evidences are mainly from deformation of the Lhasa terrane and inconsistency with the palaeontological data.
基金provided to Tehseen Zafar and greatly supported by grants of Institute of Geology,University of the Punjab Lahore,Pakistan.
文摘Mansehra Granite(MG)is massive and sheared which contains light-gray to jet-black schistosed and light-gray micaceous quartzite restites.The later possess relatively higher quartz as compared with mica contents whereas the former has predominant quartz and feldspar.Enclosure of apatite and zircon in micas and absence of sillimanite in schistosed and non-foliated facies suggest that these rocks are restite in nature.
文摘The present communication aims at an assessment of the current status on petrological evolution of the Eastern Ghats Belt in the context of its correlation with three supercontinents,namely Columbia,Rodinia and East Gondwana.Despite intensive research by different groups over the last three decades,various issues remain unresolved.Some major outstanding issues include,the nature of the basement for the Eastern Ghats rocks,isotopic and/or lithotectonic subdivisions of the belt,nature of the retrograde path of UHT metamorphism and timing of juxtaposition of the mobile belt with the adjacent cratons.
基金supported by Russian Foundation for Basic Research(project 10-05-00040 to OGS)Russian President Grants for Young Scientists(MD-222.2012.5 to OGS)+1 种基金grant from the National Science Foundation of South Africa(GUN:20531 92 to DDvR)University of Johannesburg as a part of the Russian South African scientific collaboration
文摘Reaction textures and fluid inclusions in the -2.0 Ga pyroxene-bearing dehydration zones within the Sand River biotite-hornblende orthogneisses （Central Zone of the Limpopo Complex） suggest that the formation of these zones is a result of close interplay between dehydration process along ductile shear zones triggered by H2O-CO2-salt fluids at 750--800 ℃ and 5.5--6.2 kbar, partial melting, and later exsolution of residual brine and H2O-CO2 fluids during melt crystallization at 650--700 ℃. These processes caused local variations of water and alkali activity in the fluids, resulting in various mineral assemblages within the dehydration zone. The petrological observations are substantiated by experiments on the interaction of the Sand River gneiss with the H2O-CO2-（K, Na）Cl fluids at 750 and 800 ℃ and 5.5 kbar. It follows that the interaction of biotite-amphibole gneiss with H2O-CO2-（K, Na）CI fluids is accompanied by partial melting at 750--800 ℃. Orthopyroxene-bearing assemblages are characteristic for temperature 800 ℃ and are stable in equilibrium with fluids with low salt concentrations, while salt-rich fluids produce clinopyroxene-bearing assemblages. These observations are in good agreement with the petrological data on the dehydration zones within the Sand River olthogneisses.
文摘The influence of water is evaluated in this last contribution of a series aiming to study the petrological and dynamic evolution of mantle melting.Water is considered to be either a chemical component in the melt or solid assemblage but it can also be present as a pure water phase in a oversaturated environment.A three-phase-flow model was developed for this purpose.Only a limited set of conditions has been applied to the 1-D upwelling mantle column.A range of fixed temperatures(1150-1450℃) and water contents in the solid mantle(0,0.02 wt.%,0.2 wt.%) have been imposed at the entry point(120 km deep) for the two melting models introduced in the previous installments,dynamic equilibrium melting(DEM) and dynamic fractional melting(DFM) model.As expected,for a given temperature at the base of the mantle column,the depth of the first melt formation increases with higher water content in the mantle.After the first melt is created,very negligible amount of melt is formed over a certain depth interval which approximately ends at the depth where the first melting of the dry mantle would take place.However melt is present as a dynamic phase thorough the entire region regardless whether the DEM or DFM model has been applied.Under a quasi-steady state regime,the melt and residual mantle compositions vary significantly over depth,depending on the conditions imposed to the model(DEM,DFM,bottom temperature and water content).Several distinctions can be made at the extraction point(top of the mantle column=15 km deep).For DEM and DFM models at this lowest depth,the most influential factor affecting the melt composition after the quasi-steady state condition has been reached is the temperature at the base of the column.In general,for a high temperature model,the input water in the mantle does not seem to play a significant role on the bulk composition of the melt(except for the water content in melt).But at low temperature water does have some noticeable influence on the variation of some chemical components in melt(SiO2,Fe2 O3,CaO,Na2 O at T=1250℃ or lower).A similar conclusion can be made also for the residual mantle composition.The presence of a dynamic free water phase is detected only in absence of melt or in coexistence with a melt phase when the mantle is relatively cold(bottom temperature≤1250℃) and the input water content at the base of the model is relatively high(0.2 wt.%).Complete output data for several numerical simulations and six animations illustrating various melting models are available following the instructions in the supplementary material.
基金Project supported by the National Natural Science Foundation of China (No. 40472040) and Starting Fund of Education Ministry, China
文摘The western Iratsu mass, the largest tectonic body in the Sambagawa metamorphic belt, central Shikoku, is mainly composed of epidote amphibolite with minor amounts of eclogite. Systematically, a majority of garnets show bell-shaped chemical zoning of pyrope contents and Mg/(Mg+Fe2+) monotonously increasing outward. The grossular component in zonal garnet increases outwards, maximizes at an intermediate part, and then decreases towards the outermost rim, reflecting a process from increasing to decreasing pressure conditions during the prograde metamorphism. Jadeite contents of omphacite range from 25～20mole% within the cores to 15～10 mole% at the rims, implying a pressure-decreasing process (from 11 × 105 Pa to 8 × 105 Pa). The peak pressure-temperature (P-T) condition of 630～680 ℃ and ca. 15× 105 Pa in the western Iratsu mass is much higher than that of (610±25) ℃ and (10± 1)× 105 Pa of the Sambagawa oligoclase-biotite zone schists. The authors suggest a clockwise P-T-t path for the western Iratsu mass.
文摘A K-rich volcano zone , Wudalianchi-Erkeshan - Keluo in Heilongjiang Province of Northeastern China , is studied in this paper . Some results from the study of mantle inclusions , accumulative inclusions and megacrysts are reported here for the first time . On the petrological , experimental , and magma-dynamical study of the host rocks and their inclusions and megacrysts , it is concluded that the K-rich magma in these areas was derived from upper mantle with rich in K2O and incompatible element by partial melting of phlogopite-bearing Iherzolite. Leucite picrite magma is primary and the magma represented by leucite basalt is derivative one of both fractional crystallization and assimilation . The mantle where the magma came from had undergone both the depletion and enrichment events , and had high geotherm similar to that of mid -oceanic ridge and rift valley . Mantle metasomatism , uplift and diapirism result in the K-rich volcanic rocks . The environment of volcanism in these areas is rift tectonics within continental plate ,and the composition and distribution of volcanic rocks in these areas are controlled by mantle-reach faults , and are not directly related to the subduction of the Pacific plate .
基金supported by the Korea Polar Research Institute(PE19030)for Y.I.Leethe Polar Academic Program(PE19900),KOPRI for H.S.Lim.
文摘The provenance of modern beach sands from the Barton and Weaver peninsulas of King George Island,South Shetland Islands,West Antarctica was investigated based on their modal composition and geochemical data.The source rocks and provenance tectonic setting are interpreted as volcanic and plutonic rocks formed in the magmatic arc setting.This interpretation is generally consistent with the currently distributed bedrocks in the ice-free areas and tectonic setting of King George Island.However,the composition of beach sands of the Barton and Weaver peninsulas is different from distribution of bedrocks exposed in the ice-free areas of both peninsulas.The present beach sands are interpreted as previous subaqueous moraines that were eroded and transported by advancing glaciers across the both peninsulas and deposited in front of the glacier grounding line.In other words,sand sediments in the beaches of the two peninsulas were not derived from bedrocks currently exposed in ice-free areas,but it is interpreted that they were subaqueous moraines before deglaciation and were mixed with sediment derived from wave erosion of bedrocks and sediments of the paleoshoreline during the isostatic uplift of King George Island.Finally,they were reworked under the current beach environments.
基金supported by National Natural Science Foundation of China(grant no.42403041)Scientific Base and Talent Special Projects of Guangxi(grant no.AD23026084)Scientific Research Foundation of Guilin University of Technology(GUTQDJJ6614023).
文摘NWA 16080 is a representative reduced CV carbonaceous chondrite(CV_(red)),consisting mainly of chon-drules(47 vol%)and matrix(42 vol%),along with minor quantities of calcium-and aluminum-rich inclusions(CAI)and amoeboid olivine aggregates(AOA)(CAI+AOA,6 vol%)and opaque minerals(5 vol%).The chondrules exhibit well-preserved outlines and can be categorized into Type Ⅰ(Fa<10)and Type Ⅱ(Fa>10).They primarily consist of magnesium-rich olivine,along with both low-Ca and high-Ca pyroxenes,and contain minor amounts of secondary plagioclase.Olivines present in chondrules display compositional zoning characterized whereas the matrix is composed of fine-grained olivine.Nickel-rich metal and nickel-poor sulfides are also present,along with trace amounts of magnetite.In contrast to standard oxidized CV chondrites(CV_(ox)),the presence of high metal,Ni-poor sulfides,and reduced magnetite in NWA 16080 indicates a more reduced parent-body environment.Shock metamorphism is classified as mild(S1),while terrestrial weathering is characterized as low(W2).Raman spectroscopy indicates a diverse spectrum of organic matter(OM)maturity:certain areas exhibit characteristics akin to other CV_(red) chondrites,whereas others reach maturity levels comparable to those observed in CV_(ox) chondrites.The Raman parameters indicate that this meteorite is classified as approximately type 3.4 to 3.5.The overlapping OM maturity with certain CV_(ox) chondrites provides a contradiction to the anticipated depth-thermal layering outlined in the onion-shell model.This suggests that the CV parent body probably experienced more intricate processes,including impacts and fluid-rock interactions,rather than merely depth-dependent heating.
基金supported by funds from the Ministry of Science and Technology of the People's Republic of China(No.2019YFA0708603)NSFC(Nos.41973050,42288201,41930215)the Key Special Project for Introduced Talents Team of Southern Marine Science and Engineering Guangdong Laboratory(Guangzhou)(No.GML2019ZD0202)。
文摘Mineralogical data are presented for the peridotite xenoliths from Miocene(~19 Ma)Qingyuan basalts in the eastern North China Craton(NCC),with the aim of constraining on property of the sub-continental lithospheric mantle(SCLM)beneath the northern Tan-Lu fault zone(TLFZ)during the Cenozoic.The Qingyuan peridotites are dominated by spinel lherzolites with moderate-Mg^(#)olivines(89.4 to 91.2),suggesting that the regional SCLM is mainly transitional and fertile.Light rare earth element(LREE)-depleted,slightly depleted and enriched clinopyroxenes(Cpx)are identified in different peridotites.Chemical compositions of the LREE-enriched Cpx and the presence of phlogopite suggest that the Qingyuan SCLM has experienced silicate-related metasomatism.The synthesis of available mineral chemical data of the mantle xenoliths across the NCC confirms the SCLM beneath the NCC is highly heterogeneous in time and space.The Mesozoic–Cenozoic SCLM beneath the TLFZ and neighboring regions are more fertile and thinner than that beneath the region away from the fault zone.The fertile and refractory peridotite xenoliths experienced varying degrees of silicate and carbonatite metasomatism,respectively.The spatial-temporal lithospheric mantle heterogeneity in composition,age and thickness suggest that the trans-lithosphere fault zone played an important role in heterogeneous replacement of refractory cratonic lithospheric mantle.
文摘1AIM AND SCOPE Geoscience Frontiers(GSF)publishes peer reviewed research articles and reviews in interdisciplinary fields of Earth and Planetary Sciences.GSF bridges innovative,provocative and challenging concepts and models related to various fields of research including petrology and geochemistry in understanding lithospheric architecture and mantle dynamics,global tectonics,economic geology and fuel exploration,geophysics,stratigraphy and paleontology with insights on correlations and evolution,environmental and engineering geology,astrogeology,nexus of resources-energy-emissions-climate under Sustainable Development Goals,among other themes.
基金funded by the National Natural Science Foundation of China(No.42220104008)。
文摘Research into metamorphism plays a pivotal role in reconstructing the evolution of continent,particularly through the study of ancient rocks that are highly susceptible to metamorphic alterations due to multiple tectonic activities.In the big data era,the establishment of new data platforms and the application of big data methods have become a focus for metamorphic rocks.Significant progress has been made in creating specialized databases,compiling comprehensive datasets,and utilizing data analytics to address complex scientific questions.However,many existing databases are inadequate in meeting the specific requirements of metamorphic research,resulting from a substantial amount of valuable data remaining uncollected.Therefore,constructing new databases that can cope with the development of the data era is necessary.This article provides an extensive review of existing databases related to metamorphic rocks and discusses data-driven studies in this.Accordingly,several crucial factors that need to be taken into consideration in the establishment of specialized metamorphic databases are identified,aiming to leverage data-driven applications to achieve broader scientific objectives in metamorphic research.
基金financially supported by the National Natural Science Foundation of China(No.41930215)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)。
文摘Phase equilibrium modeling using internally consistent thermodynamic dataset and associated activity-composition(a-x)models are very helpful for quantifying P-T evolution for eclogite,which is the basis for deciphering the geodynamic processes in subduction zones.In this study,we apply different versions of datasets(ds55 and ds62)and associated a-x relations to a wellestablished LT-HP eclogite at Huwan in the classic western Dabie orogen to constrain its P-T evolution.The eclogite comprises garnet+omphacite+amphibole+white mica+epidote+quartz+chlorite+rutile/ilmenite/sphene.Garnet porphyroblasts show mono-variation in the end members(spessartine from 17 mol%to 0,pyrope from 2 mol%to 18 mol%,almandine from 47 mol%to 64mol%and grossular from 35 mol%to 18 mol%)from core to rim.Phase diagrams combined with compositional isopleth thermobarometry show that dataset ds62 and associated a-x relations yield P_(max)of~33 kbar at~560℃,conflicting with our petrological observations and previous studies.On the other hand,phase equilibrium modeling using dataset ds62 and a revised symmetric garnet a-x model irrespective of Fe^(3+)(O)gives P_(max)of~27 kbar at~560℃,consistent with the results using dataset ds55 and associated a-x relations.Therefore,we recommend a symmetric model for garnet involving py,alm,gr and spss,without Fe~(3+)components,instead of the asymmetric garnet a-x relations involving py,alm,gr,spss and kho by White et al.(2014),for calculating phase diagrams for LT-(U)HP eclogite when using dataset ds62.In this study,the defined P-T path is characterized by a segment of the prograde evolution showing a first moderate slope,followed by gentle then steep slopes,representing the thermal structure evolution recorded by slab surface during continental subduction.Our work combined with previous studies conclude that in western Dabie,the Huwan HP eclogite belt to the north and the Hong'an HP eclogite belt to the south belong to the same HP slice overlying the Xinxian UHP slice.
基金jointly supported by the Natural Science Foundation of China(Nos.42172056,41772052)。
文摘A-type rocks have drawn considerable attention in the past few decades due to their distinctive mineralogical and geochemical fingerprints and prospective utility for geodynamic reconstruction of the lithosphere.A comprehensive study,involving zircon U-Pb geochronology,wholerock elemental and Sr-Nd-Pb isotopic geochemistry,was undertaken to elucidate the origin and evolutionary process for syenites from the Daguiping area in the North Daba mountains,South Qinling belt.The syenites revealed an Ordovician igneous crystallization age of 454.4±17 Ma,coeval with the neighboring mafic rocks.All samples show high SiO_(2),LREEs,and HFSEs(Nb,Ta,Zr and Hf)contents,with negative to slightly positive Eu(Eu/Eu^(*)=0.78-1.08)anomalies.The geochemical characteristics of the Daguiping syenites imply that they are of A_1-type magmatic affinity,which is confirmed by their high total alkali levels(8.57 wt.%-11.94 wt.%),Zr+Nb+Ce+Y contents(738.00 ppm-1734.78 ppm),and 10000×Ga/Al ratios(3.25-4.22),as well as low Y/Nb ratios(0.30-0.40).Our samples exhibit a wide range of initial^(87)Sr/^(86)Sr ratios of 0.701943 to 0.709802 and a narrow range of^(143)Nd/^(144)Nd ratios of 0.512205-0.512246 withε_(Nd)(t)values from+3.0 to+3.8.These rocks display(^(206)Pb/^(204)Pb)_(initial),(^(207)Pb/^(204)Pb)_(initial),and(^(208)Pb/^(204)Pb)_(initial)ratios range from 17.96 to 18.62,15.55 to 15.59,and 36.87 to 38.22,respectively.All of the isotopic data indicate that the syenites were essentially mantle-derived.A cogenetic source for the Daguiping syenites and coeval mafic rocks in the South Qinling belt is supported by their uniform Sr-Nd-Pb isotope data and linear major/trace elemental changes,with prolonged fractional crystallization considered as the essential mechanism for these geochemical discrepancies.Mass-balance and Rayleigh fractionation modeling estimate~85 vol%fractional crystallization involving amphibole,clinopyroxene,plagioclase,Kfeldspar,biotite,Fe-Ti oxide,and quartz,to reproduce the compositional varieties between a coeval mafic rock and the Daguiping syenites.The Daguiping syenites and associated alkaline rocks were likely related to a rifting episode triggered by asthenospheric upwelling,which led to the South Qinling detaching from the South China Block along the Mianlue suture during the Early Paleozoic.
基金jointly supported by the Science and Technology Development Project of PetroChina Hangzhou Institute of Petroleum Geology(No.RIPED-2020-JS-51008)the Naturacl Science Foundation of China(Nos.41872250,41802159)。
文摘Fluid-rock interaction plays a critical function in physical and chemical processes associated with the formation and evolution of oil and gas reservoir space.In the diagenetic stage of shallow burial,the dissolution of carbonate rocks by acidic fluids is conducive to the development of secondary pore space in reservoirs.In contrast,the free drift experiment based on water bath instrument can simulate the dissolution process of carbonate rocks in shallow burial environment effectively.In order to study the shallow burial dissolution mechanism of carbonate rocks in different acid solutions,14 samples of typical carbonate rocks of Sinian,Cambrian,Ordovician,Permian and Triassic ages in the Tarim and Sichuan basins,China were used.The dissolution experiments on carbonate rocks in sulfuric acid,acetic acid,hydrochloric acid,silicic acid and carbonic acid at shallow burial temperature(30℃≤T≤90℃)were carried out using a water bath instrument.The PHREEQC software was used to simulate the dissolution of carbonate minerals,in order to compare the results of constant temperature water bath experiment.The results show that acid solutions have significant dissolution effect on shallow burial carbonate rocks when T=50–60℃,which corresponds to the burial depth of 1500–2000 m in the Tarim Basin and 1110–1480 m in the Sichuan Basin.However,there were obvious differences in the dissolution and reformation of carbonate rocks in different acids.In particular,sulfuric acid solution produced by thermochemical sulfate reduction can significantly promote the dissolution of carbonate rocks,especially dolomitic limestone.Moreover,the dissolution of limestone reservoirs is stronger than that of dolomite reservoirs in shallow burial.The results will provide new insights into the study of dissolution laws and influencing factors of reservoir spaces and the evaluation and prediction of carbonate reservoirs in China.
基金The University of Malaya's postdoctoral fellowship program has been acknowledged by the first author and is associated with grant number IF064-2019the Department of Science and Technology (Project No. SB/S4/ES-681/2013), Government of India, for their supportthe Researchers Supporting Project number (RSPD2024R546) at King Saud University in Riyadh, Saudi Arabia
文摘The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in India.For over a decade,the exploration and extraction of hydrocarbons in these basins.Paleocene-Eocene age rocks bear organic-rich sediments in these basins,including lignite and carbonaceous shale deposits.The present research investigates the source rock properties,petroleum potential and thermal maturity of the carbonaceous shale partings from the lignite mines of Gurha(Bikaner-Nagaur Basin)and Kapurdi(Barmer Basin)using petrographical and geochemical tools.The carbonaceous shales have high organic matter(OM),with considerable total organic carbon(TOC)contents ranging from 13%to 39%.Furthermore,they contain hydrogen-rich kerogen,including types II and II/III,as evidenced by the Rock-Eval and elemental analysis results.The existence of these kerogen types indicates the abundance of reactive(vitrinite and liptinite)macerals.However,the carbonaceous shales from the Bikaner–Nagaur Basin have oil generation potentials,with a high hydrogen index(up to 516 mg HC/g TOC)and a H/C ratio(up to 1.5)along with a significant presence of oil-prone liptinitic macerals.Apart from the geochemical and petrological results,the studied shales have low huminite reflectance(0.31%–0.48%),maximum temperature(S_(2) peak;Tmax)between 419℃ and 429℃,and low production index values(PI:0.01–0.03).These results indicate that these carbonaceous shales contain immature OM,and thereby,they cannot yet release commercial amount of oil.This immaturity level in the studied outcrop section is due to the shallow burial depth.Geochemical proxies further indicate the presence of both oil and gas-prone source rocks.
基金financially supported by the National Natural Science Foundation of China(Nos.42207197,42293355,41672285,42293350,42341101)the Fundamental Research Funds for the Central Universities(Nos.300102264917,300102262908,590123008)。
文摘Massive granitic rock avalanches are extensively developed in the middle section of the northern Qinling Mountains(NQM),China.The current consensus is that their formation could have been connected with seismic events that occurred in the NQM.However,there is a lack of systematic discussion on the genetic dynamics of these rock avalanches.Hence,taking Earth system scientific research as a starting point,this paper systematically summarizes and discusses development characteristics,formation times and genetic dynamic mechanisms of granitic rock avalanches in the NQM based on geological investigations,high-precision remote sensing interpretations,geomorphological dating,geophysical exploration,and a large-scale shaking table model test.We identified 53 granitic rock avalanches in this area,with a single collapse area ranging from 0.01×10~6 to 1.71×10~6 m^(2).Their development time can be divided into six stages,namely,107000 years BP,11870–11950 years BP,11000 years BP,2300 years BP,1800 years BP,and 1500 years BP,which were closely related to multiple prehistoric or ancient earthquakes.We suggest that long-term coupling of internal and external earth dynamics was responsible for the granitic rock avalanches in the NQM;the internal dynamics were mainly related to subduction,collision and extrusion of different plates under the Qinling terrane,leading to the formation and tectonic uplift of the Qinling orogenic belt;and the external dynamics were closely associated with climate changes resulting in mountain denudation,freeze-thaw cycles and isostatic balance uplift.In this process,the formation and evolution of the Qinling orogenic belt play a geohazard-pregnant role,structural planes,including faults and joints,play a geohazard-controlled role,and earthquakes play a geohazard-induced role,which jointly results in the occurrence of large-scale granitic rock avalanches in the NQM.This research can not only decipher the genetic dynamic mechanism of large hard granitic rock avalanches but also reveal temporal and spatial patterns of the evolution of breeding and the generation of large-scale rock avalanches in the margins of orogenic belts.
