There is no consensus on the tectonic evolution of the western Jiangnan Orogen(WJO)during 770-750 Ma.Thus,we reported zircon trace elements and U‐Pb‐Hf‐O isotopes and whole-rock geochemistry of the Neoproterozoic t...There is no consensus on the tectonic evolution of the western Jiangnan Orogen(WJO)during 770-750 Ma.Thus,we reported zircon trace elements and U‐Pb‐Hf‐O isotopes and whole-rock geochemistry of the Neoproterozoic tuff located in Longsheng,northern Guangxi,in the WJO,to decipher their origin and tectonic setting.The SIMS U‐Pb zircon age yields a concordia age of 772.1±3.8 Ma,suggesting that the tuff layer formed at 770 Ma.Geochemical data of the tuff and its zircon exhibit continental arc signatures.Oxygen isotopes of the zircon show normal mantle zirconδ^(18)O zircon values of 4.59‰-5.50‰with an average of 5.24‰.The zircon yielded positive ε_(Hf)(t)values of 1.8-5.8 with two-stage model ages of 1.32-1.55 Ga.Based on these data and previous studies,the magma source for the tuff is inferred to have originated from the partial melting of the Mesoproterozoic juvenile crust,as the pre-existing arc materials and mixing with the mantle source under the extensional setting during 770-750 Ma triggered by the slab break-off.We infer that the presence of contemporaneous OIB-type and arc-like magmatism at ca.770-750 Ma along the WJO was related to the slab break-off.展开更多
1.Objective,The Cretaceous succession is characteristic of the aeolian sedimentary system in the Ordos Basin,which is the major ore-bearing layer for the sandstone-type uranium deposits.Based on the research of paleon...1.Objective,The Cretaceous succession is characteristic of the aeolian sedimentary system in the Ordos Basin,which is the major ore-bearing layer for the sandstone-type uranium deposits.Based on the research of paleontology and magnetostratigraphy,formers believed it belonged to the Early Cretaceous(Huang YB,2010).However,the lack of intrusions or volcanic rocks for isotopic dating results in an unclear formation age for the Lower Cretaceous succession.Recently,tuffs were firstly discovered in the Luohandong Formation in the Zhenyuan area,Gansu Province,located in the southwestern Ordos Basin,China.The LA-ICP-MS zircon U-Pb dating of tuffs was carried out.The new ages can precisely constrain the depositional age of the Luohandong Formation and also provide significant indications for the study of regional volcanic activities,paleoclimate,basin evolution,and tectonic setting.展开更多
The Ordos Basin, as the second largest petroliferous basin of China, contains abundant oil and gas resources, oil shale, and sandstone-type uranium mineral resources. Chang 7 shale is not only the major source rock of...The Ordos Basin, as the second largest petroliferous basin of China, contains abundant oil and gas resources, oil shale, and sandstone-type uranium mineral resources. Chang 7 shale is not only the major source rock of the Mesozoic petroliferous system of the Basin, but is also crucial in determining the space-time distribution relationship of the shale section for the effective exploration and development of the Basin's oil and gas resources. To obtain a highly precise age of the shale development section, we collected tuff samples from the top and bottom profile of the Chang 7 Member, Yishi Village, Yaoqu Town, Tongchuan District, on the southern margin of the Ordos Basin and performed high-precision chemical abrasion(CA)–isotope dilution(ID)–thermal ionization mass spectrometry(TIMS) zircon U-Pb dating on the basis of extensive laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) zircon U-Pb dating data. Our results show the precise ages of the top and bottom zircon in the Chang 7 shale to be 241.06±0.12 Ma and 241.558±0.093 Ma, respectively. We first obtained Chang 7 age data with Grade 0.1-Ma precision and then determined the age of the shale development in the Chang 7 Member to be the early-Middle Triassic Ladinian. This result is supported by paleontological evidence. The deposition duration of the Chang 7 shale is 0.5 Ma with an average deposition rate of the shale section being 5.3 cm/ka. Our research results provide time scale and basic data for further investigation of the basin–mountain coupling relation of the shale section, the sedimentary environment and volcanic ash and organic-matter-rich shale development relation, and the organism break-out and organic-matter enrichment mechanism.展开更多
Compaction rates of sediments or volcaniclastic material are needed to reconstruct original thickness of a bed, which in turn is required to reconstruct subsidence rates, sea-level rise, or in the case of volcanielast...Compaction rates of sediments or volcaniclastic material are needed to reconstruct original thickness of a bed, which in turn is required to reconstruct subsidence rates, sea-level rise, or in the case of volcanielastic, the location or direction of the eruption site. The knowledge of compaction rates can also aid in the reconstruction of deformed fossils. The known shape of deformed fossils can allow the determination of the compaction they experienced. Here we report the compaction rate in an early Permian volcanic tuff from Wuda, Inner Mongolia, determined from the deformation of standing tree fern stems of known anatomy. The compaction rate has been found to be 0.56 in this case, indicating that 44% of original thickness remains.展开更多
Quantitative thickness estimation below tuning thickness is a great challenge in seismic exploration. Most studies focus on the thin-beds whose top and bottom reflection coefficients are of equal magnitude and opposit...Quantitative thickness estimation below tuning thickness is a great challenge in seismic exploration. Most studies focus on the thin-beds whose top and bottom reflection coefficients are of equal magnitude and opposite polarity. There is no systematic research on the other thin-bed types. In this article, all of the thin-beds are classified into four types： thin-beds with equal magnitude and opposite polarity, thin-beds with unequal magnitude and opposite polarity, thin-beds with equal magnitude and identical polarity, and thin-beds with unequal magnitude and identical polarity. By analytical study, an equation describing the general relationship between seismic peak frequency and thin-bed thickness was derived which shows there is a Complex implicit non-linear relationship between them and which is difficult to use in practice. In order to solve this problem, we simplify the relationship by Taylor expansion and discuss the precision of the approximation formulae with different orders for the four types of thin-beds. Compared with the traditional amplitude method for thin-bed thickness calculation, the method we present has a higher precision and isn＇t influenced by the absolute value of top or bottom reflection coefficient, so it is convenient for use in practice.展开更多
Early Cretaceous rhyolitic tuffs, widely distributed on Port Island, provide insights into the volcanism and tectonic setting of Hong Kong. In this paper we present petrological, geochronological and geochemical data ...Early Cretaceous rhyolitic tuffs, widely distributed on Port Island, provide insights into the volcanism and tectonic setting of Hong Kong. In this paper we present petrological, geochronological and geochemical data of the rhyolitic tuff to constrain the diagenesis age and petrogenesis of the rocks, tectonic setting and early Cretaceous volcanism of Hong Kong. The first geochronological data show that the zircons in the volcanic rocks have U-Pb age of 141.1-139.5 Ma, which reveals that the rhyolitic tuff on Port Island was formed in the early Cretaceous （K1）. Geochemically, these acid rocks, which are enriched in large ion lithophile elements （LILEs） and light rare earth elements （LREEs）, and depleted in high field strength elements （HFSEs）, belong to the high K calc-alkaline to shoshonite series with strongly-peraluminous characteristic. The geochemical analyses suggest that the volcanic rocks were derived from deep melting in the continental crust caused by basaltic magma underplating. Based on the geochemical analysis and previous studies, we concluded that the rhyolitic tufts on Port Island were formed in a back- arc extension setting in response to the subduction of the Paleo-Pacific Plate beneath the Eurasian Plate.展开更多
This study examines the use of intact samples as an alternative to powder in conventional batch sorption studies to determine the distribution coefficient(K_d).Stable cesium(^(133)Cs) and strontium(^(87)Sr) were used ...This study examines the use of intact samples as an alternative to powder in conventional batch sorption studies to determine the distribution coefficient(K_d).Stable cesium(^(133)Cs) and strontium(^(87)Sr) were used under specified geochemical conditions to compare the Kdvalues of powder and block pumice tuff samples. The aim of the study was to infer any Kddifference under laboratory and field conditions. Kdvalues for block samples were found to be less than one order of magnitude lower than powder materials for both Cs and Sr on fresh tuff, and more than one order of magnitude lower in oxidized tuff. Destruction of micropores in oxidized tuff was estimated to be mainly responsible for reducing Kdvalues in oxidized tuff. However, approximately one order of magnitude difference in Kdvalues indicates that homogenously prepared intact samples can be used for sorption coefficient measurement at closer to in situ conditions. Pore size distribution analysis using mercury intrusion porosimetry revealed that lower Kdvalues on block samples result from lower surface area available as sorption sites due to inaccessible closed pores in the intact solid.展开更多
The mechanical and physical properties of TUFF from Korsimoro (Burkina Faso) were investigated for use as admixtures in clinker to make pozzolanic cement. Six different cement mortar specimens were prepared by replaci...The mechanical and physical properties of TUFF from Korsimoro (Burkina Faso) were investigated for use as admixtures in clinker to make pozzolanic cement. Six different cement mortar specimens were prepared by replacing clinker with TUFF in ratios of 0%, 5%, 8%, 10%, 13% and 15% by mass. The flexural and compressive strengths of the specimens were determined at the ages of 2, 7, 28 and 60 days. The effects of the TUFF replacement ratio on workability, setting time and volume expansion were also examined. Based on the results, it was concluded that Korsimoro TUFF has pozzolanic activity and is suitable for use as an alternative adherent material in the cement industry.展开更多
In 2011, petroleum exploration of shallow marine deposits Carboniferous and volcanic tuff reservoir re- alized breakthroughs at Chepaizi slope in the western margin of Junggar Basin. Pal 61 well, with 855.7 949.6 m se...In 2011, petroleum exploration of shallow marine deposits Carboniferous and volcanic tuff reservoir re- alized breakthroughs at Chepaizi slope in the western margin of Junggar Basin. Pal 61 well, with 855.7 949.6 m section, in the conventional test oil obtained 6 t/d industrial oil flow. The surface viscosity is 390 mPa. s （50 ℃）. The marine deposit of Carboniferous are deep oil source rocks and high-quality reservoir. Magma volcanic activity provides the basis for volcanic reservoir development and distribution. The weathering crust and secondary cracks developed volcanic tuff by strong rock weathering and dissolution of organic acids which has become top quality reservoir. Deep Permian oil-gas migrated and accumulated to high parts along Hong-Che fault belt and stratigraphic unconformity stripping. Permian and Triassic volcanic rocks or dense mudstone sedimentary cover as a regional seal for the late Carboniferous oil-gas to save critically. The seismic pre-stack time migration processing technologies for the problem of poor inner structures of Carboniferous were developed. Response of volcanic rock seismic and logging are obvious. The application imaging logging and nuclear magnetic technology achieved the qualitative identification and quantification of fracture description.展开更多
In-situ oxidation of solid phase was considered to investigate adsorption behavior under different geochemical parameters like pH, initial concentration and ionic strength. Pumice tuff, a potential host rock for low a...In-situ oxidation of solid phase was considered to investigate adsorption behavior under different geochemical parameters like pH, initial concentration and ionic strength. Pumice tuff, a potential host rock for low and intermediate radioactive wastes, has been affected by the redox zone. The characterization of the fresh and oxidized tuff was performed by X-ray diffractometer, scanning electron microscope and mercury intrusion porosimetry. In order to compare the difference of distribution coefficient (K<sub>d</sub>) in fresh and oxidized pumice tuffs, a batch adsorption study was carried out at the range of pH (4 - 12), ionic strength (0.003, 0.1, 1.0 and 3.0 mol/dm<sup>3</sup>) and initial cesium concentration (10<sup>dž</sup>, 10<sup>LJ</sup>, 10<sup>Lj</sup> and 10<sup>lj</sup> mol/dm<sup>3</sup>). Based on experimental K<sub>d</sub> values, ionic strength was found to be the most influential factor, whereas the effects of pH, initial Cs concentration and weathering condition of pumice tuff were negligible. The recalculated K<sub>d</sub> values suggest that the existing surface complexation model is applicable to explain the sorption coefficients through the wide range of solution conditions.展开更多
In the present investigation, two zeolite-rich tuffs from Guaymas and El Cajon（State of Sonora）, which were conditioned with a sodium chloride solution and subsequently modified with a thiourea solution, were chosen...In the present investigation, two zeolite-rich tuffs from Guaymas and El Cajon（State of Sonora）, which were conditioned with a sodium chloride solution and subsequently modified with a thiourea solution, were chosen to evaluate the removal of Cd from aqueous systems. The zeolitic materials were characterized by scanning electron microscopy and X-ray diffraction. The surface area was also determined. The experiments were performed in a batch system, and the influences of p H, contact time between phases, and the concentration of Cd in the solution on the adsorption by sodium or thiourea-modified zeolite-rich tuff were investigated. It was found that the efficiency of Cd ion removal from aqueous solutions is influenced by the p H of the aqueous systems. The Cd adsorption kinetic data were well fitted to a pseudo-second-order model in all cases. The Langmuir and Langmuir–Freundlich isotherms adequately described the Cd sorption behavior by the zeolite from El Cajon pretreated with Na Cl and the zeolite from Guaymas modified with thiourea, respectively.展开更多
A first report on tuff beds from the Owk Shale in the Proterozoic Kurnool sub-basin in southern India is presented. The rhyolitic to rhodacitic tufts, overlying shelfal limestones formed at depths below storm wave bas...A first report on tuff beds from the Owk Shale in the Proterozoic Kurnool sub-basin in southern India is presented. The rhyolitic to rhodacitic tufts, overlying shelfal limestones formed at depths below storm wave base, have rheomorphie features indicative of viscoplastic flow, and geochem- ical signatures of rhyolitic to rhyodacitic unwelded to welded tufts, similar to those described from other Proterozoic intracratonic basins like Vindhyan and Chhattisgarh basins in India. Fragmentary nature of altered glass with perlitic cracks and local admixture with intrabasinal sediments suggest phreatomag- matic reactions. The widespread and repeated occurrences of felsic tufts in these basins, possibly derived from low degree melting of continental crust, suggest intermittent tectonothermal instability which likely influenced basinal topography and cyclic development of the carbonate platforms.展开更多
A comprehensive petrographic observation contributes to classification of various textures in welded tuffs into two types, the textures in plastic fragments and the ones in rigid fragments. A detailed petrographic stu...A comprehensive petrographic observation contributes to classification of various textures in welded tuffs into two types, the textures in plastic fragments and the ones in rigid fragments. A detailed petrographic study of the textures in plastic fragments leads to suggestion that thesetextures are not a type of devitrification textures. and also that they were formed not by devitrification but by undercooling crystallization. This viewpoint is supported by results of undercooling crystallization experiments. The petrographic characteristics of these textures are satisfactorily demonstrated by the undercooling crystallization theory.展开更多
The objective of this project is the valorization of Mako andesitic volcanic tuffs for use in social housing in the Kedougou region. To achieve these objectives, a geotechnical characterization of the tuff samples was...The objective of this project is the valorization of Mako andesitic volcanic tuffs for use in social housing in the Kedougou region. To achieve these objectives, a geotechnical characterization of the tuff samples was carried out and the geopolymerization stabilization was adopted for the manufacture of bricks. These bricks stabilized by an alkaline activation offer compressive strengths that exceed the threshold value (2.9 MPa) set by the standard (NF P14-304). The best compressive strengths (12.14 MPa) and flexural tensile strengths (5.43 MPa) are obtained in the series of bricks made with 35% of the mass of a solution of caustic soda at 12 molars concentration with a curing temperature cooking of 185°C and an average absorbance of 13.21%.展开更多
The authors studied zircon U-Pb age and geochemical data of Baicaogou tuff in Yanji,Jilin Province.The results indicate that the rocks formed in Early Cretaceous( 125. 6 ± 2. 3 Ma). Geochemically,these tuffs have...The authors studied zircon U-Pb age and geochemical data of Baicaogou tuff in Yanji,Jilin Province.The results indicate that the rocks formed in Early Cretaceous( 125. 6 ± 2. 3 Ma). Geochemically,these tuffs have high Si O2 and total Na2 O + K2 O,low Mg O and Fe O,and they belong to metaluminous series,the rock are enriched in LREEs and LILEs,depleted in HREEs and HFSEs such as Nb,Ta,Ti,and P,exhibiting an affinity to I-type granite. All these characteristics implied that the volcanic rocks were derived from partial melting of lower crust. Combined with the geochronology and geochemical features of the coeval igneous rocks within NE China,it is concluded that Yanji area was in a back-arc extensional setting in response to the subduction of the Paleo-Pacific Plate beneath the Eurasian Plate.展开更多
基金supported by the National Natural Science Foundation of China(No.41972069)National Major Science and Technology Project on Deep Earth(No.2024ZD1001208)the China Geological Survey(No.DD20221645,DD20221648).
文摘There is no consensus on the tectonic evolution of the western Jiangnan Orogen(WJO)during 770-750 Ma.Thus,we reported zircon trace elements and U‐Pb‐Hf‐O isotopes and whole-rock geochemistry of the Neoproterozoic tuff located in Longsheng,northern Guangxi,in the WJO,to decipher their origin and tectonic setting.The SIMS U‐Pb zircon age yields a concordia age of 772.1±3.8 Ma,suggesting that the tuff layer formed at 770 Ma.Geochemical data of the tuff and its zircon exhibit continental arc signatures.Oxygen isotopes of the zircon show normal mantle zirconδ^(18)O zircon values of 4.59‰-5.50‰with an average of 5.24‰.The zircon yielded positive ε_(Hf)(t)values of 1.8-5.8 with two-stage model ages of 1.32-1.55 Ga.Based on these data and previous studies,the magma source for the tuff is inferred to have originated from the partial melting of the Mesoproterozoic juvenile crust,as the pre-existing arc materials and mixing with the mantle source under the extensional setting during 770-750 Ma triggered by the slab break-off.We infer that the presence of contemporaneous OIB-type and arc-like magmatism at ca.770-750 Ma along the WJO was related to the slab break-off.
基金supported by the Science&Technology Fundamental Resources Investigation Program of China(2022FY101800)the National Science Foundation of China(92162212)the International Geoscience Programme(IGCP 675).
文摘1.Objective,The Cretaceous succession is characteristic of the aeolian sedimentary system in the Ordos Basin,which is the major ore-bearing layer for the sandstone-type uranium deposits.Based on the research of paleontology and magnetostratigraphy,formers believed it belonged to the Early Cretaceous(Huang YB,2010).However,the lack of intrusions or volcanic rocks for isotopic dating results in an unclear formation age for the Lower Cretaceous succession.Recently,tuffs were firstly discovered in the Luohandong Formation in the Zhenyuan area,Gansu Province,located in the southwestern Ordos Basin,China.The LA-ICP-MS zircon U-Pb dating of tuffs was carried out.The new ages can precisely constrain the depositional age of the Luohandong Formation and also provide significant indications for the study of regional volcanic activities,paleoclimate,basin evolution,and tectonic setting.
基金supported by the National Basic Research Program of China (973 Program) granted No. 2014CB239001
文摘The Ordos Basin, as the second largest petroliferous basin of China, contains abundant oil and gas resources, oil shale, and sandstone-type uranium mineral resources. Chang 7 shale is not only the major source rock of the Mesozoic petroliferous system of the Basin, but is also crucial in determining the space-time distribution relationship of the shale section for the effective exploration and development of the Basin's oil and gas resources. To obtain a highly precise age of the shale development section, we collected tuff samples from the top and bottom profile of the Chang 7 Member, Yishi Village, Yaoqu Town, Tongchuan District, on the southern margin of the Ordos Basin and performed high-precision chemical abrasion(CA)–isotope dilution(ID)–thermal ionization mass spectrometry(TIMS) zircon U-Pb dating on the basis of extensive laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS) zircon U-Pb dating data. Our results show the precise ages of the top and bottom zircon in the Chang 7 shale to be 241.06±0.12 Ma and 241.558±0.093 Ma, respectively. We first obtained Chang 7 age data with Grade 0.1-Ma precision and then determined the age of the shale development in the Chang 7 Member to be the early-Middle Triassic Ladinian. This result is supported by paleontological evidence. The deposition duration of the Chang 7 shale is 0.5 Ma with an average deposition rate of the shale section being 5.3 cm/ka. Our research results provide time scale and basic data for further investigation of the basin–mountain coupling relation of the shale section, the sedimentary environment and volcanic ash and organic-matter-rich shale development relation, and the organism break-out and organic-matter enrichment mechanism.
基金supported by the Chinese Academy of Science Project KZCX2-EW-120National basic Research Program of China (973 Program, 2012CB821901)+2 种基金the National Natural Science Foundation of China to J. W.a grant from the University Research FoundationOther funding from the University of Pennsylvania to H. W. P. during field research
文摘Compaction rates of sediments or volcaniclastic material are needed to reconstruct original thickness of a bed, which in turn is required to reconstruct subsidence rates, sea-level rise, or in the case of volcanielastic, the location or direction of the eruption site. The knowledge of compaction rates can also aid in the reconstruction of deformed fossils. The known shape of deformed fossils can allow the determination of the compaction they experienced. Here we report the compaction rate in an early Permian volcanic tuff from Wuda, Inner Mongolia, determined from the deformation of standing tree fern stems of known anatomy. The compaction rate has been found to be 0.56 in this case, indicating that 44% of original thickness remains.
基金supported by National Key S&T Special Projects of Marine Carbonate 2008ZX05000-004CNPC Projects 2008E-0610-10
文摘Quantitative thickness estimation below tuning thickness is a great challenge in seismic exploration. Most studies focus on the thin-beds whose top and bottom reflection coefficients are of equal magnitude and opposite polarity. There is no systematic research on the other thin-bed types. In this article, all of the thin-beds are classified into four types： thin-beds with equal magnitude and opposite polarity, thin-beds with unequal magnitude and opposite polarity, thin-beds with equal magnitude and identical polarity, and thin-beds with unequal magnitude and identical polarity. By analytical study, an equation describing the general relationship between seismic peak frequency and thin-bed thickness was derived which shows there is a Complex implicit non-linear relationship between them and which is difficult to use in practice. In order to solve this problem, we simplify the relationship by Taylor expansion and discuss the precision of the approximation formulae with different orders for the four types of thin-beds. Compared with the traditional amplitude method for thin-bed thickness calculation, the method we present has a higher precision and isn＇t influenced by the absolute value of top or bottom reflection coefficient, so it is convenient for use in practice.
基金supported by a geological survey program of Agriculture,Fisheries and Conservation Department of Hong Kong Special Administrative Region(Grant No.AFCD/SQ/92/14)
文摘Early Cretaceous rhyolitic tuffs, widely distributed on Port Island, provide insights into the volcanism and tectonic setting of Hong Kong. In this paper we present petrological, geochronological and geochemical data of the rhyolitic tuff to constrain the diagenesis age and petrogenesis of the rocks, tectonic setting and early Cretaceous volcanism of Hong Kong. The first geochronological data show that the zircons in the volcanic rocks have U-Pb age of 141.1-139.5 Ma, which reveals that the rhyolitic tuff on Port Island was formed in the early Cretaceous （K1）. Geochemically, these acid rocks, which are enriched in large ion lithophile elements （LILEs） and light rare earth elements （LREEs）, and depleted in high field strength elements （HFSEs）, belong to the high K calc-alkaline to shoshonite series with strongly-peraluminous characteristic. The geochemical analyses suggest that the volcanic rocks were derived from deep melting in the continental crust caused by basaltic magma underplating. Based on the geochemical analysis and previous studies, we concluded that the rhyolitic tufts on Port Island were formed in a back- arc extension setting in response to the subduction of the Paleo-Pacific Plate beneath the Eurasian Plate.
文摘This study examines the use of intact samples as an alternative to powder in conventional batch sorption studies to determine the distribution coefficient(K_d).Stable cesium(^(133)Cs) and strontium(^(87)Sr) were used under specified geochemical conditions to compare the Kdvalues of powder and block pumice tuff samples. The aim of the study was to infer any Kddifference under laboratory and field conditions. Kdvalues for block samples were found to be less than one order of magnitude lower than powder materials for both Cs and Sr on fresh tuff, and more than one order of magnitude lower in oxidized tuff. Destruction of micropores in oxidized tuff was estimated to be mainly responsible for reducing Kdvalues in oxidized tuff. However, approximately one order of magnitude difference in Kdvalues indicates that homogenously prepared intact samples can be used for sorption coefficient measurement at closer to in situ conditions. Pore size distribution analysis using mercury intrusion porosimetry revealed that lower Kdvalues on block samples result from lower surface area available as sorption sites due to inaccessible closed pores in the intact solid.
文摘The mechanical and physical properties of TUFF from Korsimoro (Burkina Faso) were investigated for use as admixtures in clinker to make pozzolanic cement. Six different cement mortar specimens were prepared by replacing clinker with TUFF in ratios of 0%, 5%, 8%, 10%, 13% and 15% by mass. The flexural and compressive strengths of the specimens were determined at the ages of 2, 7, 28 and 60 days. The effects of the TUFF replacement ratio on workability, setting time and volume expansion were also examined. Based on the results, it was concluded that Korsimoro TUFF has pozzolanic activity and is suitable for use as an alternative adherent material in the cement industry.
基金National Planed Major S&T Projects(No.2011ZX05002-002)Scientific Research Project of Sinopec(No.P03011)Key Technology Tacking Project,Shengli Oilfield Company,Sinopec(No.YKK0808)
文摘In 2011, petroleum exploration of shallow marine deposits Carboniferous and volcanic tuff reservoir re- alized breakthroughs at Chepaizi slope in the western margin of Junggar Basin. Pal 61 well, with 855.7 949.6 m section, in the conventional test oil obtained 6 t/d industrial oil flow. The surface viscosity is 390 mPa. s （50 ℃）. The marine deposit of Carboniferous are deep oil source rocks and high-quality reservoir. Magma volcanic activity provides the basis for volcanic reservoir development and distribution. The weathering crust and secondary cracks developed volcanic tuff by strong rock weathering and dissolution of organic acids which has become top quality reservoir. Deep Permian oil-gas migrated and accumulated to high parts along Hong-Che fault belt and stratigraphic unconformity stripping. Permian and Triassic volcanic rocks or dense mudstone sedimentary cover as a regional seal for the late Carboniferous oil-gas to save critically. The seismic pre-stack time migration processing technologies for the problem of poor inner structures of Carboniferous were developed. Response of volcanic rock seismic and logging are obvious. The application imaging logging and nuclear magnetic technology achieved the qualitative identification and quantification of fracture description.
文摘In-situ oxidation of solid phase was considered to investigate adsorption behavior under different geochemical parameters like pH, initial concentration and ionic strength. Pumice tuff, a potential host rock for low and intermediate radioactive wastes, has been affected by the redox zone. The characterization of the fresh and oxidized tuff was performed by X-ray diffractometer, scanning electron microscope and mercury intrusion porosimetry. In order to compare the difference of distribution coefficient (K<sub>d</sub>) in fresh and oxidized pumice tuffs, a batch adsorption study was carried out at the range of pH (4 - 12), ionic strength (0.003, 0.1, 1.0 and 3.0 mol/dm<sup>3</sup>) and initial cesium concentration (10<sup>dž</sup>, 10<sup>LJ</sup>, 10<sup>Lj</sup> and 10<sup>lj</sup> mol/dm<sup>3</sup>). Based on experimental K<sub>d</sub> values, ionic strength was found to be the most influential factor, whereas the effects of pH, initial Cs concentration and weathering condition of pumice tuff were negligible. The recalculated K<sub>d</sub> values suggest that the existing surface complexation model is applicable to explain the sorption coefficients through the wide range of solution conditions.
基金supported by the National Institute of Nuclear Researches(project CB-505)CONACyT(project 254665)SEP-TecNM(project 2340.09-P)
文摘In the present investigation, two zeolite-rich tuffs from Guaymas and El Cajon（State of Sonora）, which were conditioned with a sodium chloride solution and subsequently modified with a thiourea solution, were chosen to evaluate the removal of Cd from aqueous systems. The zeolitic materials were characterized by scanning electron microscopy and X-ray diffraction. The surface area was also determined. The experiments were performed in a batch system, and the influences of p H, contact time between phases, and the concentration of Cd in the solution on the adsorption by sodium or thiourea-modified zeolite-rich tuff were investigated. It was found that the efficiency of Cd ion removal from aqueous solutions is influenced by the p H of the aqueous systems. The Cd adsorption kinetic data were well fitted to a pseudo-second-order model in all cases. The Langmuir and Langmuir–Freundlich isotherms adequately described the Cd sorption behavior by the zeolite from El Cajon pretreated with Na Cl and the zeolite from Guaymas modified with thiourea, respectively.
基金supported by the Indian Statistical Institute(ISI), Kolkata in the form of several research grants to DS during the past decadeVT acknowledges a senior research fellowship granted by ISI during the initial stage of the worka DST grant(SR/S4/ES-307/2007) which partly supported this work
文摘A first report on tuff beds from the Owk Shale in the Proterozoic Kurnool sub-basin in southern India is presented. The rhyolitic to rhodacitic tufts, overlying shelfal limestones formed at depths below storm wave base, have rheomorphie features indicative of viscoplastic flow, and geochem- ical signatures of rhyolitic to rhyodacitic unwelded to welded tufts, similar to those described from other Proterozoic intracratonic basins like Vindhyan and Chhattisgarh basins in India. Fragmentary nature of altered glass with perlitic cracks and local admixture with intrabasinal sediments suggest phreatomag- matic reactions. The widespread and repeated occurrences of felsic tufts in these basins, possibly derived from low degree melting of continental crust, suggest intermittent tectonothermal instability which likely influenced basinal topography and cyclic development of the carbonate platforms.
文摘A comprehensive petrographic observation contributes to classification of various textures in welded tuffs into two types, the textures in plastic fragments and the ones in rigid fragments. A detailed petrographic study of the textures in plastic fragments leads to suggestion that thesetextures are not a type of devitrification textures. and also that they were formed not by devitrification but by undercooling crystallization. This viewpoint is supported by results of undercooling crystallization experiments. The petrographic characteristics of these textures are satisfactorily demonstrated by the undercooling crystallization theory.
文摘The objective of this project is the valorization of Mako andesitic volcanic tuffs for use in social housing in the Kedougou region. To achieve these objectives, a geotechnical characterization of the tuff samples was carried out and the geopolymerization stabilization was adopted for the manufacture of bricks. These bricks stabilized by an alkaline activation offer compressive strengths that exceed the threshold value (2.9 MPa) set by the standard (NF P14-304). The best compressive strengths (12.14 MPa) and flexural tensile strengths (5.43 MPa) are obtained in the series of bricks made with 35% of the mass of a solution of caustic soda at 12 molars concentration with a curing temperature cooking of 185°C and an average absorbance of 13.21%.
文摘The authors studied zircon U-Pb age and geochemical data of Baicaogou tuff in Yanji,Jilin Province.The results indicate that the rocks formed in Early Cretaceous( 125. 6 ± 2. 3 Ma). Geochemically,these tuffs have high Si O2 and total Na2 O + K2 O,low Mg O and Fe O,and they belong to metaluminous series,the rock are enriched in LREEs and LILEs,depleted in HREEs and HFSEs such as Nb,Ta,Ti,and P,exhibiting an affinity to I-type granite. All these characteristics implied that the volcanic rocks were derived from partial melting of lower crust. Combined with the geochronology and geochemical features of the coeval igneous rocks within NE China,it is concluded that Yanji area was in a back-arc extensional setting in response to the subduction of the Paleo-Pacific Plate beneath the Eurasian Plate.
