In order to constrain whether the Lhasa–Qiangtang collision contributed to an early crustal thickening of the central Tibetan Plateau prior to the India–Asia collision,we present zircon LA–ICP–MS U–Pb ages,wholer...In order to constrain whether the Lhasa–Qiangtang collision contributed to an early crustal thickening of the central Tibetan Plateau prior to the India–Asia collision,we present zircon LA–ICP–MS U–Pb ages,wholerock geochemistry,and zircon Hf isotopic compositions of the newly discovered rhyolitic crystal tuffs from the Chuduoqu area in the eastern Qiangtang subterrane,central Tibet.Zircon U–Pb dating suggests that the Chuduoqu rhyolitic crystal tuffs were emplaced at ca.68 Ma.The Chuoduoqu rhyolitic crystal tuffs display high SiO_(2) and K2 O,and low MgO,Cr,and Ni.Combined with their zircon Hf isotopic data,we suggest that they were derived from partial melting of the juvenile lower crust,and the magma underwent fractional crystallization and limited upper continental crustal assimilation during its evolution prior to eruption.They should be formed in a post-collisional environment related to lithospheric mantle delamination.The Chuduoqu rhyolitic crystal tuffs could provide important constraints on the Late Cretaceous crustal thickening of the central Tibetan Plateau caused by the Lhasa–Qiangtang collision.展开更多
The volcanic tuffs of Senegal-Oriental in Mako area are produced during a calc-alkaline volcanism which occurs in this region and which is dated from about 2.3 - 1.95 Ga. Despite their altered appearance, the X-Ray di...The volcanic tuffs of Senegal-Oriental in Mako area are produced during a calc-alkaline volcanism which occurs in this region and which is dated from about 2.3 - 1.95 Ga. Despite their altered appearance, the X-Ray diffractions show mineral paragenesis: Quartz-Kaolinite-Illite and an important amorphous phase. On the Ternary Keil-Rankin diagram for the CaO-SiO2-Al2O3 the volcanic tuffs of Mako area are situated between pozzolan and the fly ash. The difference between silica and lime is greater than 34% in these volcanic tuffs. In this study, they have been mixed with Portland cement to obtain pozzolanic cements respectively with 20%, 30%, 35% and 40% of addition of volcanic tuffs. The pozzolanic reactivity is highlighted by the compressive strength increase until 90 days of conservation in water. It supposes that the vitreous phase of the volcanic tuffs reacts with the free CaO (CaOf) of Portland cement to produce new hydrated minerals. This study has a positive economic and environmental impact. Because the time of grinding of pozzolanic cements is reduced. Also, the addition of volcanic tuffs reduces the production of clinker, then the CO2 emission.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
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
In this study, the geological, petrographical properties of rhyolitic tuffs exposed around ?an-Etili in the Biga Peninsula (NW Turkey) which are pyroclastic products of Late Oligocene-Early Miocene aged ?an Volcanism ...In this study, the geological, petrographical properties of rhyolitic tuffs exposed around ?an-Etili in the Biga Peninsula (NW Turkey) which are pyroclastic products of Late Oligocene-Early Miocene aged ?an Volcanism were investigated, also physical and mechanical characteristics of tuffs introduced and tried to determine the impact on engineering properties of petrographical features. In the region, rhyolitic tuffs called locally “?an stone” have been used as covering and building stones for many years. These tuffs generally have light yellowish, beige, brown colored and different patterns with light yellowish, cream, reddish and brown colors caused by iron oxidation of hydrothermal alteration. They are preferred as coatings and decorative stone with these patterns. ?an stone which consisted of rhyolitic composition, lithic and locally crystalline tuffs has compact structure. The mineral assemblage of tuffs is mainly composed of quartz, plagioclase, rarely biotite, amphibole (hornblende) phenocrystals and opaque mineral with particles of volcanic glass and lithic fragments. Not only petrographical and geochemical analyses were carried out but also standard rock mechanic tests (unit weight, specific gravity, porosity, water absorption and uniaxial compressive strength) on rhyolitic tuffs samples collected from four different quarries (Hoppa Hill, Halilaga, Uzunalan, Dereoba). Simple regression analysis of test results obtained from four different regions and correlations were found good correlation between engineering proper- ties and the petrographical and chemical properties of rhyolitic tuffs.展开更多
This investigation reports the first discovery of more than 70 tuff intervals in the Upper Triassic,South Qilian Basin.Petrographic and geochemical analyses were carried out on ten tuff samples and zircon U-Pb dating ...This investigation reports the first discovery of more than 70 tuff intervals in the Upper Triassic,South Qilian Basin.Petrographic and geochemical analyses were carried out on ten tuff samples and zircon U-Pb dating were on three.Thin section and X-ray diffraction(XRD)results indicate that the tuffs were composed of crystal shards and altered glass shards;crystal shards include plagio-clase and quartz.Most of the tuffs had been transformed into illite/smectite mixed-layers(I/S).In addition,calcite,pyrite,dolomite and siderite were also identified in some of the tuff samples.Analysis of major elements suggests that the tuffs are peraluminous high-K calcalkaline series.Trace elements indicate that the tuffs are enriched in high field strength elements(HFSE),including Th,U,Ta,Zr and Hf.Geochemical characteristics suggest that the tuffs originated from comendite pantellerite and rhyolite from within plate setting.Zircon U-Pb dating(236.0±1.7,231.4±1.6,and 223.1±3.9 Ma)indicate that the tuffs were erupted in the Late Triassic.Comparative chronology and geochemical analyses suggest that the West Qinling belt and the East Kunlun belt are the potential source regions of these tuffs,and they originated from the within plate magma during a post-collisional period.展开更多
Both the NE Gondwana Platform (Jordan) and the Carpathian/NW Europe Seaway towards the N Atlantic expose comparable sequence analytical patterns as i.e. the Maximum Flooding Surface (MSF), relating to the Arabian Shel...Both the NE Gondwana Platform (Jordan) and the Carpathian/NW Europe Seaway towards the N Atlantic expose comparable sequence analytical patterns as i.e. the Maximum Flooding Surface (MSF), relating to the Arabian Shelf, throughout one of the warmest Phanerozoic Epochs. Supervolcanic Large Igneous Provinces (LIPs), (explosive island arc andesitic volcanism), Mid-Oceanic Rift Basalts (MORB), (S/N Atlantic, Arctic) and kimberlitic volcanism (W Gondwana) provided striking conditions for an immense influence (tuff, degassing, T) on the sedimentary processing throughout the Cretaceous, mainly verified by K-montmorillonite , dozens of tuff beds (predominantly in NW Germany), zeolite, cristobalite, extremely high chert occurrences as well as the reconfirming of the global anoxic event around the Cenomanian/Turonian b. (94 Ma) by a positive ∂13C-maximum (~0.5%). Thus the lithofacies spectrum (carbonate rocks, chalk, chert, porcellanite, shale) was affected by pH, Eh, T, photosynthesis, and greenhouse gases—change during varying positive/negative climate forcing. While acid sturzrain events caused the transformation of arkosic/subarkosic sediments of the hinterlands to quartz arenite cycles deposited on the Jordanian Platform during early Cretaceous, the other patterns mentioned, led to a rapid change of lithofacies through Late Cretaceous. The southward directed Neotethys transgression can be reconstructed during the Early Cretaceous by glauconite-aged tidalites that give hint on transpressional tectonics during the Upper Cenomanian east of the Dead Sea. The Cretaceous/Paleogene (K-Pg) transitional zone evidences a zone of several cumulative events (island arc-volcanism) and the Chicxulub impact, indicated by at least two extinctions phases. The southward obduction of the Palmyrides, Syria and related transtensional/transpressional strike slip tectonics (partially pull-apart structures) left a fast facies change on the Jordanian Platform.展开更多
End-Permian Gondwana siliciclastics (50 - 70 m) of the Um Irna F exposed along the NE Dead Sea, exhibit carbonate-free fining upward cycles (FUC) deposited during acid flash flood events under tropical climate. Severa...End-Permian Gondwana siliciclastics (50 - 70 m) of the Um Irna F exposed along the NE Dead Sea, exhibit carbonate-free fining upward cycles (FUC) deposited during acid flash flood events under tropical climate. Several ferruginous paleosol intercalations cover periods of drying upward formation (DUP) under semiarid/arid climates. Thin grey pelite beds interbedded between paleosol and overlying FUC, are interpreted as tephra deposits sourced in Siberian LIP- and Neo-Tethys (NT)-Degassing. The Wadi Bassat en Nimra-section exhibits the P-T transitional zone where flash flood deposits meet supra-/intertidal sediments of the southward-directed transgressive NT. Decreasing flash-flooding continued through the Lower Scythian (Ma’in F.) during transgression, reworking, and resedimentation. Two euryhaline foraminifera-bearing limestone beds are discussed as indicators for the end of mass extinction (recovery phase: ca. 250.8 - 250.4 Ma) possibly correlating with the Maximum Flooding Surface MFS Tr 10 (ca. 250.5 Ma) on the Arabian Shelf (Khuff cycles B;A). Comparable data from the Germanic Basin as FUC/DUP-cycles, tephrasuspicious “Grey Beds” with high concentrations of As, Co, Pb, Zn, and Cu as well as the U-Pb Age data of the Siberian LIP meet the PTB-Zone between the MFSs Intervals P 40 (ca. 254 Ma)/Tr 10 (ca 250.5 Ma) on the Arabian Shelf. MFS (Tr 10, 20, 30) and SBs resp. on the Arabian Plate, as well as Scythian Substage boundaries correlate with ∂<sup>13</sup> C-excursions recorded at Musandam, UAE. Thereby, the ratio of greenhouse gases (+climate forcing)/aerosols und tephra (-climate forcing) takes a significant influence on the ∂<sup>13</sup>C-Variation.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
This paper explores the potential implications of recent thinking in relation to rock mass strength for future tunnelling projects in Brisbane,Australia,particularly as they are constructed within deep horizons where ...This paper explores the potential implications of recent thinking in relation to rock mass strength for future tunnelling projects in Brisbane,Australia,particularly as they are constructed within deep horizons where the in situ stress magnitudes is larger.Rock mass failure mechanisms for the current tunnels in Brisbane are generally discontinuity controlled and the potential for stress-induced failure is relatively rare.For the road tunnels which have been constructed in Brisbane over the last 12 years,the strength of the more massive rock masses for continuum analysis has been estimated by the application of the Hoek-Brown(H-B)failure criterion using the geological strength index(GSI)to determine the H-B parameters mb,s and a.Over the last few years,alternative approaches to estimating rock mass strength for‘massive to moderately jointed hard rock masses’have been proposed by others,which are built on the work completed by E.Hoek and E.T.Brown in this area over their joint careers.This paper explores one of these alternative approaches to estimating rock mass strength for one of the geological units(the Brisbane Tuff),which is often encountered in tunnelling projects in Brisbane.The potential implications of these strength forecasts for future tunnelling projects are discussed along with the additional work which will need to be undertaken to confirm the applicability of such alternative strength criteria for this rock mass.展开更多
The conventional lithofacies and facies model of subaerial and marine pyroclastic rocks cannot reflect the characteristics of subaqueous volcanic edifice in lacustrine basins.In order to solve this problem,the lithofa...The conventional lithofacies and facies model of subaerial and marine pyroclastic rocks cannot reflect the characteristics of subaqueous volcanic edifice in lacustrine basins.In order to solve this problem,the lithofacies of subaqueous eruptive pyroclastic rocks is discussed and the facies model is established by taking the tuff cone of Cretaceous Huoshiling Formation in the Chaganhua area of the Changling fault depression,Songliao Basin as the research object.The results indicate that the subaqueous eruptive pyroclastic rocks in the Songliao Basin can be divided into two facies and four subfacies.The two facies are the subaqueous explosive facies and the volcanic sedimentary facies that is formed during the eruption interval.The subaqueous explosive facies can be further divided into three subfacies:gas-supported hot pyroclastic flow subfacies,water-laid density current subfacies and subaqueous fallout subfacies.The volcanic sedimentary facies consists of pyroclastic sedimentary rocks containing terrigenous clast subfacies.A typical facies model of the tuff cone that is formed by subaqueous eruptions in the Songliao Basin was established.The tuff cone is generally composed of multiple subaqueous eruption depositional units and can be divided into two facies associations:near-source facies association and far-source facies association.The complete vertical succession of one depositional unit of the near-source facies association is composed of pyroclastic sedimentary rocks containing terrigenous clast subfacies,gas-supported hot pyroclastic flow subfacies,water-laid density current subfacies and subaqueous fallout subfacies from bottom to top.The depositional unit of the far-source facies association is dominated by the subaqueous fallout subfacies and contains several thin interlayered deposits of the water-laid density current subfacies.The gas-supported hot pyroclastic flow subfacies and the pyroclastic sedimentary rocks containing terrigenous clast subfacies are favorable subaqueous eruptive facies for reservoirs in continental lacustrine basins.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
Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as pla...Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as plagioclase, biotite, and hornblende. According to the morphology and major element compositions of the representative glass shards, combined with theδ18O-based age, it is suggested that ash Layer A is cor-related to the youngest Toba tuff (YTT), Layer B is supposed to be associated with a new eruption of Toba caldera in an age of 98 to 100 ka. Ash Layer C is different the geochemistry characteristics than those of Layer A and Layer B, suggesting that Layer C was not originated from Toba but registered another volcanic erup-tion event.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
The reservoir of the Xing'anling Group in the Beier depression of the Hailar basin is loosely cemented with many tuffaceous grains.This causes argillization and collapse of the grain framework of the reservoir san...The reservoir of the Xing'anling Group in the Beier depression of the Hailar basin is loosely cemented with many tuffaceous grains.This causes argillization and collapse of the grain framework of the reservoir sandstones.A detailed study on the characteristics of rocks and minerals was carried out through polarized microscope,X-ray diffraction,X-ray fluorescence,SEM and energy spectrum analysis.The results indicate that the reason for argillization is the abundant pyroclastic,and especially tuffaceous,grains in the reservoir.The alkaline component is relatively high in some strata.These are easily altered to montmorillonite in diagenesis.Na+montmorillonite swells strongly when exposed to water.This is the fundamental reason for the reservoir's argillization and plugging.展开更多
This work deals with geopolymers based on local Jordanian resources, namely, kaolin and zeoltitic (phillipsite) tuff. The geopolymers were prepared from these two materials by a reaction with an alkali solution at 80o...This work deals with geopolymers based on local Jordanian resources, namely, kaolin and zeoltitic (phillipsite) tuff. The geopolymers were prepared from these two materials by a reaction with an alkali solution at 80oC. The research group of the present work has demonstrated in previous work that addition of zeolitic tuff to kaolin based-geopolymers increases the adsorption capacity toward Cu(II) metal ion compared to zeolite-free geopolymers, while retaining high mechanical strength. The aim of the present work is to extend our work and to study the effect of changing geopolymers components (zeolitic tuff and kaolin) on their adsorption properties toward Cu(II), Ni(II), Zn(II), Cd(II) and Pb(II) metal ions. Both isothermal and kinetic studies revealed that increasing the zeolitic tuff: kaolin ratio improves the adsorption capacity of geopolymer toward metal ions. The adsorption capacity of the geopolymers of 150: 50 zeolites: kaolin content was found to be higher than that of the raw materials themselves. The rate of adsorption of geopolymers was found to be lower than that of raw materials due to kinetic limitations imposed by the formation of geopolymerization network. The selectivity of geopolymers toward adsorption of? metal ions was found to be distinct from raw zeolite and kaolin where the adsorption onto geopolymers was found to be more preferential for small size metal ions (Cu(II), Ni(II), Zn(II)) than for large size metal ions (Pb(II), Cd(II)). The adsorption of Cu(II) and Pb(II) onto geopolymers did not decrease with competition with other metal ions, which indicates cooperative adsorption. The adsorption process of metal ions onto geopolymers was found to be reversible that indicates that metal ions are bound by physical cation exchange to the exchangeable sites of unreacted phillipsite and new amorphous geopolymer sites. Leaching of metal ions from raw kaolin was much more effective than geopolymers and zeolite because of compact structure of geopolymers.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
基金funded by the National Natural Science Foundation of China(41272093)the Geological Survey Project(12120114080901)of China Geological Survey+4 种基金the Self-determined Foundation of Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Natural Resources(DBY-ZZ-19-04)the Shandong Provincial Natural Science Foundation of China(No.ZR2019PD017)the Natural Science Foundation of Liaoning Province(2020-BS-258)the Department of Education of Liaoning Province(LJ2020JCL010)a Discipline Innovation Team Project of Liaoning Technical University(LNTU20TD-14)。
文摘In order to constrain whether the Lhasa–Qiangtang collision contributed to an early crustal thickening of the central Tibetan Plateau prior to the India–Asia collision,we present zircon LA–ICP–MS U–Pb ages,wholerock geochemistry,and zircon Hf isotopic compositions of the newly discovered rhyolitic crystal tuffs from the Chuduoqu area in the eastern Qiangtang subterrane,central Tibet.Zircon U–Pb dating suggests that the Chuduoqu rhyolitic crystal tuffs were emplaced at ca.68 Ma.The Chuoduoqu rhyolitic crystal tuffs display high SiO_(2) and K2 O,and low MgO,Cr,and Ni.Combined with their zircon Hf isotopic data,we suggest that they were derived from partial melting of the juvenile lower crust,and the magma underwent fractional crystallization and limited upper continental crustal assimilation during its evolution prior to eruption.They should be formed in a post-collisional environment related to lithospheric mantle delamination.The Chuduoqu rhyolitic crystal tuffs could provide important constraints on the Late Cretaceous crustal thickening of the central Tibetan Plateau caused by the Lhasa–Qiangtang collision.
文摘The volcanic tuffs of Senegal-Oriental in Mako area are produced during a calc-alkaline volcanism which occurs in this region and which is dated from about 2.3 - 1.95 Ga. Despite their altered appearance, the X-Ray diffractions show mineral paragenesis: Quartz-Kaolinite-Illite and an important amorphous phase. On the Ternary Keil-Rankin diagram for the CaO-SiO2-Al2O3 the volcanic tuffs of Mako area are situated between pozzolan and the fly ash. The difference between silica and lime is greater than 34% in these volcanic tuffs. In this study, they have been mixed with Portland cement to obtain pozzolanic cements respectively with 20%, 30%, 35% and 40% of addition of volcanic tuffs. The pozzolanic reactivity is highlighted by the compressive strength increase until 90 days of conservation in water. It supposes that the vitreous phase of the volcanic tuffs reacts with the free CaO (CaOf) of Portland cement to produce new hydrated minerals. This study has a positive economic and environmental impact. Because the time of grinding of pozzolanic cements is reduced. Also, the addition of volcanic tuffs reduces the production of clinker, then the CO2 emission.
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.
基金financially supported by The Scientific and Technological Research Council of Turkey(TUBI-TAK.Project No.105Y114)
文摘In this study, the geological, petrographical properties of rhyolitic tuffs exposed around ?an-Etili in the Biga Peninsula (NW Turkey) which are pyroclastic products of Late Oligocene-Early Miocene aged ?an Volcanism were investigated, also physical and mechanical characteristics of tuffs introduced and tried to determine the impact on engineering properties of petrographical features. In the region, rhyolitic tuffs called locally “?an stone” have been used as covering and building stones for many years. These tuffs generally have light yellowish, beige, brown colored and different patterns with light yellowish, cream, reddish and brown colors caused by iron oxidation of hydrothermal alteration. They are preferred as coatings and decorative stone with these patterns. ?an stone which consisted of rhyolitic composition, lithic and locally crystalline tuffs has compact structure. The mineral assemblage of tuffs is mainly composed of quartz, plagioclase, rarely biotite, amphibole (hornblende) phenocrystals and opaque mineral with particles of volcanic glass and lithic fragments. Not only petrographical and geochemical analyses were carried out but also standard rock mechanic tests (unit weight, specific gravity, porosity, water absorption and uniaxial compressive strength) on rhyolitic tuffs samples collected from four different quarries (Hoppa Hill, Halilaga, Uzunalan, Dereoba). Simple regression analysis of test results obtained from four different regions and correlations were found good correlation between engineering proper- ties and the petrographical and chemical properties of rhyolitic tuffs.
基金supported by the National Natural Science Foundation of China(Nos.41702144,42002194)the Natural Science Basic Research Plan of Shaanxi Province,China(Nos.2019JQ-991,2020JQ-746).
文摘This investigation reports the first discovery of more than 70 tuff intervals in the Upper Triassic,South Qilian Basin.Petrographic and geochemical analyses were carried out on ten tuff samples and zircon U-Pb dating were on three.Thin section and X-ray diffraction(XRD)results indicate that the tuffs were composed of crystal shards and altered glass shards;crystal shards include plagio-clase and quartz.Most of the tuffs had been transformed into illite/smectite mixed-layers(I/S).In addition,calcite,pyrite,dolomite and siderite were also identified in some of the tuff samples.Analysis of major elements suggests that the tuffs are peraluminous high-K calcalkaline series.Trace elements indicate that the tuffs are enriched in high field strength elements(HFSE),including Th,U,Ta,Zr and Hf.Geochemical characteristics suggest that the tuffs originated from comendite pantellerite and rhyolite from within plate setting.Zircon U-Pb dating(236.0±1.7,231.4±1.6,and 223.1±3.9 Ma)indicate that the tuffs were erupted in the Late Triassic.Comparative chronology and geochemical analyses suggest that the West Qinling belt and the East Kunlun belt are the potential source regions of these tuffs,and they originated from the within plate magma during a post-collisional period.
文摘Both the NE Gondwana Platform (Jordan) and the Carpathian/NW Europe Seaway towards the N Atlantic expose comparable sequence analytical patterns as i.e. the Maximum Flooding Surface (MSF), relating to the Arabian Shelf, throughout one of the warmest Phanerozoic Epochs. Supervolcanic Large Igneous Provinces (LIPs), (explosive island arc andesitic volcanism), Mid-Oceanic Rift Basalts (MORB), (S/N Atlantic, Arctic) and kimberlitic volcanism (W Gondwana) provided striking conditions for an immense influence (tuff, degassing, T) on the sedimentary processing throughout the Cretaceous, mainly verified by K-montmorillonite , dozens of tuff beds (predominantly in NW Germany), zeolite, cristobalite, extremely high chert occurrences as well as the reconfirming of the global anoxic event around the Cenomanian/Turonian b. (94 Ma) by a positive ∂13C-maximum (~0.5%). Thus the lithofacies spectrum (carbonate rocks, chalk, chert, porcellanite, shale) was affected by pH, Eh, T, photosynthesis, and greenhouse gases—change during varying positive/negative climate forcing. While acid sturzrain events caused the transformation of arkosic/subarkosic sediments of the hinterlands to quartz arenite cycles deposited on the Jordanian Platform during early Cretaceous, the other patterns mentioned, led to a rapid change of lithofacies through Late Cretaceous. The southward directed Neotethys transgression can be reconstructed during the Early Cretaceous by glauconite-aged tidalites that give hint on transpressional tectonics during the Upper Cenomanian east of the Dead Sea. The Cretaceous/Paleogene (K-Pg) transitional zone evidences a zone of several cumulative events (island arc-volcanism) and the Chicxulub impact, indicated by at least two extinctions phases. The southward obduction of the Palmyrides, Syria and related transtensional/transpressional strike slip tectonics (partially pull-apart structures) left a fast facies change on the Jordanian Platform.
文摘End-Permian Gondwana siliciclastics (50 - 70 m) of the Um Irna F exposed along the NE Dead Sea, exhibit carbonate-free fining upward cycles (FUC) deposited during acid flash flood events under tropical climate. Several ferruginous paleosol intercalations cover periods of drying upward formation (DUP) under semiarid/arid climates. Thin grey pelite beds interbedded between paleosol and overlying FUC, are interpreted as tephra deposits sourced in Siberian LIP- and Neo-Tethys (NT)-Degassing. The Wadi Bassat en Nimra-section exhibits the P-T transitional zone where flash flood deposits meet supra-/intertidal sediments of the southward-directed transgressive NT. Decreasing flash-flooding continued through the Lower Scythian (Ma’in F.) during transgression, reworking, and resedimentation. Two euryhaline foraminifera-bearing limestone beds are discussed as indicators for the end of mass extinction (recovery phase: ca. 250.8 - 250.4 Ma) possibly correlating with the Maximum Flooding Surface MFS Tr 10 (ca. 250.5 Ma) on the Arabian Shelf (Khuff cycles B;A). Comparable data from the Germanic Basin as FUC/DUP-cycles, tephrasuspicious “Grey Beds” with high concentrations of As, Co, Pb, Zn, and Cu as well as the U-Pb Age data of the Siberian LIP meet the PTB-Zone between the MFSs Intervals P 40 (ca. 254 Ma)/Tr 10 (ca 250.5 Ma) on the Arabian Shelf. MFS (Tr 10, 20, 30) and SBs resp. on the Arabian Plate, as well as Scythian Substage boundaries correlate with ∂<sup>13</sup> C-excursions recorded at Musandam, UAE. Thereby, the ratio of greenhouse gases (+climate forcing)/aerosols und tephra (-climate forcing) takes a significant influence on the ∂<sup>13</sup>C-Variation.
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.
文摘This paper explores the potential implications of recent thinking in relation to rock mass strength for future tunnelling projects in Brisbane,Australia,particularly as they are constructed within deep horizons where the in situ stress magnitudes is larger.Rock mass failure mechanisms for the current tunnels in Brisbane are generally discontinuity controlled and the potential for stress-induced failure is relatively rare.For the road tunnels which have been constructed in Brisbane over the last 12 years,the strength of the more massive rock masses for continuum analysis has been estimated by the application of the Hoek-Brown(H-B)failure criterion using the geological strength index(GSI)to determine the H-B parameters mb,s and a.Over the last few years,alternative approaches to estimating rock mass strength for‘massive to moderately jointed hard rock masses’have been proposed by others,which are built on the work completed by E.Hoek and E.T.Brown in this area over their joint careers.This paper explores one of these alternative approaches to estimating rock mass strength for one of the geological units(the Brisbane Tuff),which is often encountered in tunnelling projects in Brisbane.The potential implications of these strength forecasts for future tunnelling projects are discussed along with the additional work which will need to be undertaken to confirm the applicability of such alternative strength criteria for this rock mass.
基金Supported by the National Natural Science Foundation of China (41790453,41972313)。
文摘The conventional lithofacies and facies model of subaerial and marine pyroclastic rocks cannot reflect the characteristics of subaqueous volcanic edifice in lacustrine basins.In order to solve this problem,the lithofacies of subaqueous eruptive pyroclastic rocks is discussed and the facies model is established by taking the tuff cone of Cretaceous Huoshiling Formation in the Chaganhua area of the Changling fault depression,Songliao Basin as the research object.The results indicate that the subaqueous eruptive pyroclastic rocks in the Songliao Basin can be divided into two facies and four subfacies.The two facies are the subaqueous explosive facies and the volcanic sedimentary facies that is formed during the eruption interval.The subaqueous explosive facies can be further divided into three subfacies:gas-supported hot pyroclastic flow subfacies,water-laid density current subfacies and subaqueous fallout subfacies.The volcanic sedimentary facies consists of pyroclastic sedimentary rocks containing terrigenous clast subfacies.A typical facies model of the tuff cone that is formed by subaqueous eruptions in the Songliao Basin was established.The tuff cone is generally composed of multiple subaqueous eruption depositional units and can be divided into two facies associations:near-source facies association and far-source facies association.The complete vertical succession of one depositional unit of the near-source facies association is composed of pyroclastic sedimentary rocks containing terrigenous clast subfacies,gas-supported hot pyroclastic flow subfacies,water-laid density current subfacies and subaqueous fallout subfacies from bottom to top.The depositional unit of the far-source facies association is dominated by the subaqueous fallout subfacies and contains several thin interlayered deposits of the water-laid density current subfacies.The gas-supported hot pyroclastic flow subfacies and the pyroclastic sedimentary rocks containing terrigenous clast subfacies are favorable subaqueous eruptive facies for reservoirs in continental lacustrine basins.
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.
基金The National Natural Science Foundation of China under contract Nos 41106052 91228101 and 41306056the Fundamental Research Funds for National Nonprofit Institute Grant under contract No.JG0910
文摘Three volcanic ash layers were identified in a deep-sea Core IR-GC1 from the north-eastern Indian Ocean, adjacent to western Indonesian arc. They were dominated by glass shards with minor mineral crystals, such as plagioclase, biotite, and hornblende. According to the morphology and major element compositions of the representative glass shards, combined with theδ18O-based age, it is suggested that ash Layer A is cor-related to the youngest Toba tuff (YTT), Layer B is supposed to be associated with a new eruption of Toba caldera in an age of 98 to 100 ka. Ash Layer C is different the geochemistry characteristics than those of Layer A and Layer B, suggesting that Layer C was not originated from Toba but registered another volcanic erup-tion event.
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The reservoir of the Xing'anling Group in the Beier depression of the Hailar basin is loosely cemented with many tuffaceous grains.This causes argillization and collapse of the grain framework of the reservoir sandstones.A detailed study on the characteristics of rocks and minerals was carried out through polarized microscope,X-ray diffraction,X-ray fluorescence,SEM and energy spectrum analysis.The results indicate that the reason for argillization is the abundant pyroclastic,and especially tuffaceous,grains in the reservoir.The alkaline component is relatively high in some strata.These are easily altered to montmorillonite in diagenesis.Na+montmorillonite swells strongly when exposed to water.This is the fundamental reason for the reservoir's argillization and plugging.
文摘This work deals with geopolymers based on local Jordanian resources, namely, kaolin and zeoltitic (phillipsite) tuff. The geopolymers were prepared from these two materials by a reaction with an alkali solution at 80oC. The research group of the present work has demonstrated in previous work that addition of zeolitic tuff to kaolin based-geopolymers increases the adsorption capacity toward Cu(II) metal ion compared to zeolite-free geopolymers, while retaining high mechanical strength. The aim of the present work is to extend our work and to study the effect of changing geopolymers components (zeolitic tuff and kaolin) on their adsorption properties toward Cu(II), Ni(II), Zn(II), Cd(II) and Pb(II) metal ions. Both isothermal and kinetic studies revealed that increasing the zeolitic tuff: kaolin ratio improves the adsorption capacity of geopolymer toward metal ions. The adsorption capacity of the geopolymers of 150: 50 zeolites: kaolin content was found to be higher than that of the raw materials themselves. The rate of adsorption of geopolymers was found to be lower than that of raw materials due to kinetic limitations imposed by the formation of geopolymerization network. The selectivity of geopolymers toward adsorption of? metal ions was found to be distinct from raw zeolite and kaolin where the adsorption onto geopolymers was found to be more preferential for small size metal ions (Cu(II), Ni(II), Zn(II)) than for large size metal ions (Pb(II), Cd(II)). The adsorption of Cu(II) and Pb(II) onto geopolymers did not decrease with competition with other metal ions, which indicates cooperative adsorption. The adsorption process of metal ions onto geopolymers was found to be reversible that indicates that metal ions are bound by physical cation exchange to the exchangeable sites of unreacted phillipsite and new amorphous geopolymer sites. Leaching of metal ions from raw kaolin was much more effective than geopolymers and zeolite because of compact structure of geopolymers.
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.