Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea, the characteristics of volcanic activi- ty of the South China Sea after spreading were studied. The potassium - argon ages...Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea, the characteristics of volcanic activi- ty of the South China Sea after spreading were studied. The potassium - argon ages of eight alkali basalt samples from the South China Sea, and the argon - argon ages of two samples among them are reported. Apparent ages of the whole rock are 3.80 to 7. 91 Ma with an average value of 5.43 Ma （potassium- argon, whole rock）, and there is little difference among samples at the same location, e. g. , 4. 76 - 5.78 Ma for location S（M-12. The argon - argon ages for the two samples are 6.06 and 4. 71 Ma, which lie within the age scope of potassium - argon method. The dating results indicate that rock-forming age is from late Miocene to Pliocene, which is consistent with erupting event for alkali basalts from adjacent regions of the South China Sea. Volcanic activities occur after the cessation of spreading of the South China Sea, which are controlled by lithospheric fault and the spreading center formed during the spreading period of the South China Sea. These dating results, combined with geochemical characteristics of these basalts, the published chronological data for the South China Sea and its adjacent regions, and the updated geophysical data near Hainan Island, suggest that after the cessation of spreading of the South China Sea, there occur widely distributing magmatic activities which primarily is alkali basalt, and the volcanic activity continues to Quaternary. The activity may be relative to Hainan mantle plume originated from core/mantle boundary.展开更多
The Taohekou Formation is a volcanic-sedimentary terrane formed in the early Silurian in the northern Daba Mountains, China. The volcanic rocks, with dominant alkali basalts and minor mantle xenoliths, are enriched in...The Taohekou Formation is a volcanic-sedimentary terrane formed in the early Silurian in the northern Daba Mountains, China. The volcanic rocks, with dominant alkali basalts and minor mantle xenoliths, are enriched in clinopyroxene phenocrysts. Geochemical analysis shows that the composition of clinopyroxenes from different lithofacies has a close affinity. There is a liner correlation present in composition of clinopyroxenes （including phenocryst, microcrystal and xenocryst） from coarse porphyritic basalts, pillow or fine porphyritic basalts to amygdaloidal basalts. All the cllnopyroxenes, except the clinopyroxenes in mantle xenoliths, show a similar pattern of trace elements and REE, which indicates that they are likely products of successive fractional crystallization from cognate magma. Clinopyroxenes in mantle xenoliths, however, are mantle xenocrysts. The crystallization pressure of clinopyroxenes gradually decreases from mantle xenolith, deep-seated xenocryst, coarse porphritic basalts, pillow or fine porphritic basalts, to amygdaloidal basalts, which are 1.92-4.41 GPa, 1.18-2.36 GPa, 1.13-2.05 GPa, 0.44-0.62 GPa and 0.14-0.28 GPa respectively. Calculation results suggest that the primary magma originated from a mantle region deeper than 68 km and stagnates in intervals of 37-68 kin, 15-20 km and 5-9 km during its ascent. The alkali basalts are characterized by increasing concentrations of Si and alkaline with the magmatic evolution. Meanwhile, they are markedly enriched in LREE, and the patterns of trace elements and REE are similar to those of oceanic island basalts.展开更多
Garnet megacryst with a multiphase inclusion from intraplate alkali basalts of the Shavaryn Tsaram(Tariat,Mongolia)was the object of the study.This unusual aggregate consists of porous glass,Ti-rich biotite,orthopyrox...Garnet megacryst with a multiphase inclusion from intraplate alkali basalts of the Shavaryn Tsaram(Tariat,Mongolia)was the object of the study.This unusual aggregate consists of porous glass,Ti-rich biotite,orthopyroxene,spinel,clinopyroxene,olivine,and ilmenite.Win TWQ 2.32 thermodynamic simulation of this system revealed a few intervals of equilibrium.Pressure and temperature adjustment reflected in the paragenetic minerals of the melt pocket.The capture of already crystallised garnet megacryst was at P=0.8-1 GPa and T=1120-1160℃.Mineral crystallisation inside the melt pocket,accompanied by external inputs,occurred at P=0.75-0.95 GPa;T=790-1120℃.Symplectite assemblage formed in the garnet megacryst due to decomposition at(P=0.55-0.7 GPa;T=850-930℃).The study of the oxygen isotope content in primary garnet and biotite of the melt pocket showed that the δ^(18)O_(VSMOW) values are the same and correspond to that of typical mantle xenoliths.However,the chemical and microcomponent composition of the melt pocket minerals reveals a material that differs from basalts and peridotites.Thus,it has been revealed that the multiphase inclusion in the garnet megacryst formed not only on account of the garnet’s substance,but also due to the entrapped material of the Earth’s interior.展开更多
The noble gas isotopic composition and content data of 2 alkali basalts, 3 lherzolite xenoliths and one clinopyroxene megacryst from the Kuandian region have confirmed the occurrence of a fractionation of noble gases ...The noble gas isotopic composition and content data of 2 alkali basalts, 3 lherzolite xenoliths and one clinopyroxene megacryst from the Kuandian region have confirmed the occurrence of a fractionation of noble gases during magmatism. Light noble gases such as He and Ne are high in mobility and appear to be incompatible as compared with heavy ones (such as Kr and Xe). Therefore, light noble gases are abundant in volcanics, especially in the volcanics with bubbles; lherzolite xenoliths have relatively high heavy noble gases. The clinopyroxene megacryst has the lowest abundance of noble gases, probably due to its high P-T origin. Noble gas isotopic composition of the clinopyroxene megacryst reveals that the mantle source beneath the Kuandian area has an MORB-like reservoir with 3He/4He ratio of ～10 Ra (Ra: atmospheric 3He/4He ratio) and 40Ar/36Ar ratio of 345.6. The lherzolite xenoliths possess moderate 3He/4He ratios of 2.59-4.53 Ra, reflecting the loss of primary helium during rock deformation or metasomatism caused by enriched mantle fluids during the up-lifting. The alkali volcanics have very low 3He/4He ratios (0.47-0.61 Ra), indicating a contribution of radiogenic 4He, probably having resulted from crust contamination. Most of the samples have excess 21Ne and 22Ne as compared with atmospheric neon, but Kr and Xe isotopic compositions are indistinguishable from atmospheric values within uncertainties with only individual samples having excess 129Xe, 134Xe and 136Xe.展开更多
The fluid compositions of Cenozoic alkali basalts in eastern China have been determined by the pyrolysis MS method, meanwhile the carbon and oxygen isotopic compositions of CO 2 released from these samples at differen...The fluid compositions of Cenozoic alkali basalts in eastern China have been determined by the pyrolysis MS method, meanwhile the carbon and oxygen isotopic compositions of CO 2 released from these samples at different heating temperatures have been analyzed by the vacuum step heating method. The data show the volatile heterogeneity in upper mantle sources and different evolution trends of alkali basaltic magmas in eastern China, and these alkali basaltic magmas may be generated in the oxidizing milieu, as compared with mantle derived xenoliths in these alkali basalts, and exotic volatile components were mixed into these magmas in the process of their formation and development.展开更多
The Zarqa-Ma’in basalt (MB) occurs near a plateau basalt (wadi fills) covering about 15 km2 of Makawir, Ataruz, and Hammat um Hasana cone areas in central Jordan. The tectonic evolution occurred through intraplate vo...The Zarqa-Ma’in basalt (MB) occurs near a plateau basalt (wadi fills) covering about 15 km2 of Makawir, Ataruz, and Hammat um Hasana cone areas in central Jordan. The tectonic evolution occurred through intraplate volcanism and erupted through fissure systems along the Dead Sea, transforming the fault during Miocene to Pleistocene period. Three stages of eruption of MB have been recorded during Pleistocene from 6 to 0.6 Ma. The petrographic analyses data show that the MB rocks are composed of plagioclase, olivine, pyroxene, and magnetite, including secondary minerals calcite, iddingsite, serpentine, and zeolite. Furthermore, the MB rocks have narrow ranges of major and trace element concentrations, and are of under saturated silica type and belong to sodic alkaline magma series. The geochemical characteristics of MB indicate that MB was derived from a slightly fractionated magma as reflected by its high MgO (6.3 - 11.7 ppm) concentration with Mg number from 0.41 to 0.61, low silica content (40.83 - 47.55 wt%), and high Cr and Ni concentrations (115 - 475 and 105 - 553 ppm, respectively). This basalt exhibited low degree of partial melting (10%) for garnet peridotite mantle source. The model mineral fractionation showed that the MB could be fractionated to clinopyroxene, orthopyroxene, olivine, and plagioclase.展开更多
The main objective of this study is to examine the possibility of using fresh basalt powder in the preparation of geopolymer pastes. Four NaOH concentrations of 2.5, 5, 7.5 and 10 M were used to alkali activation of b...The main objective of this study is to examine the possibility of using fresh basalt powder in the preparation of geopolymer pastes. Four NaOH concentrations of 2.5, 5, 7.5 and 10 M were used to alkali activation of basalt. In addition, effect of curing temperature at ambient, 45°C and 65°C were studied. The geopolymer pastes were investigated using FTIR, XRD and SEM-EDS techniques as well as compressive strength up to 90 days. The results were shown the compressive strength of prepared geopolymer increased with concentration of alkali activator up to 90 days. On the other hand, the compressive strength of prepared geopolymer pastes were improved with increased curing temperature. The results showed that there was a change in the chemical and mineral structure, due to the reaction of the sodium hydroxide with the different minerals of the basalt. In addition, the Na/Al and Si/Al ratios were completely different from that of the raw basalt. The geopolymerization reactions occurred at the surface basalt and the unreacted basalt particles actually play a supporting role in the geopolymer properties.展开更多
The basalt terrain of the Neogene Huangguoshan and. Guiwu Formations of eastern Anhui on the east side of the Tancheng-Lujiang fault belt is one of a few Cenozoic basalt terrains in eastern China for which detailed ge...The basalt terrain of the Neogene Huangguoshan and. Guiwu Formations of eastern Anhui on the east side of the Tancheng-Lujiang fault belt is one of a few Cenozoic basalt terrains in eastern China for which detailed geochemical study has not been conducted. This paper reports the abundances of major elements and more than 20 trace elements (including REE) of 22 samples and the Nd, Sr and Pb isotopic compositions of 11 samples from the eastern Anhui basalt terrain, thus more or less systematically revealing the geochemical characteristics of this continental basalt suite. The paper discusses the origin of the basalt suite and the character and process of its mantle source. The basalt suite was derived from a heterogeneous continental lithospheric mantle with end members characteristic of the EMI-type oceanic basalt mantle, which was affected by mantle metasomatism (or enrichment of trace elements) and was characterized by a multi-stage evolution under open conditions.展开更多
Al Azraq Al Shamali (AZS) basaltic rocks were investigated aiming to understand their mineralogy, petrography and geochemistry features, and to achieve that a total of sixteen representative rock samples were selected...Al Azraq Al Shamali (AZS) basaltic rocks were investigated aiming to understand their mineralogy, petrography and geochemistry features, and to achieve that a total of sixteen representative rock samples were selected for both geochemical and petrographic analysis from several sites in the study area. Petrographic characteristics were analyzed by optical microscopy after preparation thin sections for representative rock samples, which show that all basalt samples have minerals comprising: olivine, plagioclase (labradorite), clinopyroxene (augite), opaque’s and some secondary minerals such as Iddingsite, however, the proportions of each mineral vary between samples. Normative mineralogy by using CIPW Norm showed that AZS basalt samples dominated by olivine, Diopside, and nepheline, and AZS basalt can be normatively classified as alkali olivine basalt. Some textures that may be evident on microscopic examination such as porphyritic, glomeroporphyritic, vesicular, intergranular, and ophitic to sub-ophitic texture. X-Ray Fluorescence was used for whole rock major elements analysis (SiO<sub>2</sub>, TiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub>, MnO, MgO, CaO, Na<sub>2</sub>O, K<sub>2</sub>O and P<sub>2</sub>O<sub>5</sub> in wt%) and trace element (V, Cr, Co, Ni, Rb, Sr, Y, Zr, Nb, Ce, Nd and Ba in ppm). Geochemical analysis reveal that the basalt is alkaline and includes into Sodic series. AZS basalt are produced under-saturated within intraplate continental environment. The normalized trace element diagrams suggest that the AZS product of the asthenosphere part of the mantle at >100 km depth. Furthermore, the data of studied samples suggest that these rocks evolved from a melt formed by low degrees of partial melting. Also the geochemical variation trends of (AZS) basaltic samples supposing that the composition of these basalt have been influenced by fractional crystallization, without clear evidences for crustal contamination.展开更多
Two kinds of basalts with different chemical compositions were obtained in the Sanshui Basin,they share the same eruption period. Although they have significant differences in major and trace element concentrations,th...Two kinds of basalts with different chemical compositions were obtained in the Sanshui Basin,they share the same eruption period. Although they have significant differences in major and trace element concentrations,their isotopic ratios suggest a similar magma source. Based on mineral geochemical analysis,orthopyroxene with reaction rim and zoned clinopyroxene are observed in Zidong(ZD)basalts,but not found in Wangjiegang(WJG) basalts. Linear scanning of these minerals suggests compositional variation between within-plate tholeiite and within-plate alkali-basalt. Presence of a doublelayer magma chamber under the Sanshui Basin,and occurrence of magma mixing between upper and lower chambers is proposed. This magma mixing leads to different chemical composition and mineral constitution of two kinds of basalts,as well as reaction rim and compositional variation of minerals in ZD basalts.展开更多
This research was conducted to investigate the mineralogy, petrography, geochemistry and petrogensis of the basaltic flows in Jurf Ed Darawish (JDB) area of central Jordan. Sexton representative basalt rock samples we...This research was conducted to investigate the mineralogy, petrography, geochemistry and petrogensis of the basaltic flows in Jurf Ed Darawish (JDB) area of central Jordan. Sexton representative basalt rock samples were selected from the studied JDB outcrops. Modally, JDB consists of plagioclase, olivine, pyroxene (diopside), opaque’s, calcite and iddingsite minerals. Petrographically, basalt is holocrystalline, hypidiomorphic fine to medium grained and exhibited aphanitic to porphyritic texture. The common textures of the JDB rock samples were aphanitic, porphyritic, trachytic, glomeroporphyritic, sub ophitic, vesicular, and amygdaloidal. Geochemically, all of the inspected samples of JDB are located within Trachy basalt and plate alkaline basalt. The tectonic setting of JDB was plotted within the calcalkaline basalt and continental basaltic field. The rare-earth elements showed enrichment of the Ba and K, depletion of Ce relative to K, and enrichment of Nb and Pb with depletion of Y and positive Nb, Zr and Ti anomalies. Negative anomalies of Ba, Sr, Ti and P may be attributed to the fractionation of feldspar for Ba and Sr depletion apatite for P depletion. The positive Nb peak conforms to the tertiary as well as to recent continental alkali basalt provinces and acts as an indicator to the JDB product for the lithosphere from upwelling of the asthenosphere mantle.展开更多
The study is carried out to list mineralogy and texture of the basalt in Hail region. The basalt flows belong to the Arabian Harrat volcanism. Cenozoic volcanism has produced 13, vast, basaltic fields in western Saudi...The study is carried out to list mineralogy and texture of the basalt in Hail region. The basalt flows belong to the Arabian Harrat volcanism. Cenozoic volcanism has produced 13, vast, basaltic fields in western Saudi Arabia, covering a total area of about 100,000 sq. km. The volcanism starts in the late Cretaceous time and continues periodically into the Holocene. The basaltic field presently investigated is known as Harrat Al-Hamad (or Harrat As-Shamah) which lies in northwestern Saudi Arabia, and continues northwards into Jordan. Mineralogical analysis of 20 rock samples indicates that the rocks are products of continental intra-plate magmatism;mostly as coarse-grained silica—under saturated olivine-rich alkali basalt. Mineralogical study shows that rocks are olivine, plagioclase, pyroxene, Nepheline and Opaque minerals. They correspond to alkali olivine basalts. Moreover, the main well-defined texture is intergranular, vesicular and amygdaloidal texture.展开更多
基金The Special Basic Research Fund for Central Public Research Institutes (First Institute of Oceanograpgy,State Oceanic Administration)under contract No.GY02 -2008G38the Special Plan of Science and Technology Generalship in Qingdao under contract No.05-2 -JC-79the Special Project of Technical Foundational Work and Social Public Welfare Research under contract No.2003DIB3J114
文摘Based on the isotopic chronologic results of Cenozoic alkali basalts from the South China Sea, the characteristics of volcanic activi- ty of the South China Sea after spreading were studied. The potassium - argon ages of eight alkali basalt samples from the South China Sea, and the argon - argon ages of two samples among them are reported. Apparent ages of the whole rock are 3.80 to 7. 91 Ma with an average value of 5.43 Ma （potassium- argon, whole rock）, and there is little difference among samples at the same location, e. g. , 4. 76 - 5.78 Ma for location S（M-12. The argon - argon ages for the two samples are 6.06 and 4. 71 Ma, which lie within the age scope of potassium - argon method. The dating results indicate that rock-forming age is from late Miocene to Pliocene, which is consistent with erupting event for alkali basalts from adjacent regions of the South China Sea. Volcanic activities occur after the cessation of spreading of the South China Sea, which are controlled by lithospheric fault and the spreading center formed during the spreading period of the South China Sea. These dating results, combined with geochemical characteristics of these basalts, the published chronological data for the South China Sea and its adjacent regions, and the updated geophysical data near Hainan Island, suggest that after the cessation of spreading of the South China Sea, there occur widely distributing magmatic activities which primarily is alkali basalt, and the volcanic activity continues to Quaternary. The activity may be relative to Hainan mantle plume originated from core/mantle boundary.
基金supported by the National Science Foundation of China (project 40872147/40472119)the basic outlay of scientific research work from the Ministry of Science and Technology of China(project 2006BAB01A11)the Geological Survey Project of China(project 12120100782003-13)
文摘The Taohekou Formation is a volcanic-sedimentary terrane formed in the early Silurian in the northern Daba Mountains, China. The volcanic rocks, with dominant alkali basalts and minor mantle xenoliths, are enriched in clinopyroxene phenocrysts. Geochemical analysis shows that the composition of clinopyroxenes from different lithofacies has a close affinity. There is a liner correlation present in composition of clinopyroxenes （including phenocryst, microcrystal and xenocryst） from coarse porphyritic basalts, pillow or fine porphyritic basalts to amygdaloidal basalts. All the cllnopyroxenes, except the clinopyroxenes in mantle xenoliths, show a similar pattern of trace elements and REE, which indicates that they are likely products of successive fractional crystallization from cognate magma. Clinopyroxenes in mantle xenoliths, however, are mantle xenocrysts. The crystallization pressure of clinopyroxenes gradually decreases from mantle xenolith, deep-seated xenocryst, coarse porphritic basalts, pillow or fine porphritic basalts, to amygdaloidal basalts, which are 1.92-4.41 GPa, 1.18-2.36 GPa, 1.13-2.05 GPa, 0.44-0.62 GPa and 0.14-0.28 GPa respectively. Calculation results suggest that the primary magma originated from a mantle region deeper than 68 km and stagnates in intervals of 37-68 kin, 15-20 km and 5-9 km during its ascent. The alkali basalts are characterized by increasing concentrations of Si and alkaline with the magmatic evolution. Meanwhile, they are markedly enriched in LREE, and the patterns of trace elements and REE are similar to those of oceanic island basalts.
文摘Garnet megacryst with a multiphase inclusion from intraplate alkali basalts of the Shavaryn Tsaram(Tariat,Mongolia)was the object of the study.This unusual aggregate consists of porous glass,Ti-rich biotite,orthopyroxene,spinel,clinopyroxene,olivine,and ilmenite.Win TWQ 2.32 thermodynamic simulation of this system revealed a few intervals of equilibrium.Pressure and temperature adjustment reflected in the paragenetic minerals of the melt pocket.The capture of already crystallised garnet megacryst was at P=0.8-1 GPa and T=1120-1160℃.Mineral crystallisation inside the melt pocket,accompanied by external inputs,occurred at P=0.75-0.95 GPa;T=790-1120℃.Symplectite assemblage formed in the garnet megacryst due to decomposition at(P=0.55-0.7 GPa;T=850-930℃).The study of the oxygen isotope content in primary garnet and biotite of the melt pocket showed that the δ^(18)O_(VSMOW) values are the same and correspond to that of typical mantle xenoliths.However,the chemical and microcomponent composition of the melt pocket minerals reveals a material that differs from basalts and peridotites.Thus,it has been revealed that the multiphase inclusion in the garnet megacryst formed not only on account of the garnet’s substance,but also due to the entrapped material of the Earth’s interior.
文摘The noble gas isotopic composition and content data of 2 alkali basalts, 3 lherzolite xenoliths and one clinopyroxene megacryst from the Kuandian region have confirmed the occurrence of a fractionation of noble gases during magmatism. Light noble gases such as He and Ne are high in mobility and appear to be incompatible as compared with heavy ones (such as Kr and Xe). Therefore, light noble gases are abundant in volcanics, especially in the volcanics with bubbles; lherzolite xenoliths have relatively high heavy noble gases. The clinopyroxene megacryst has the lowest abundance of noble gases, probably due to its high P-T origin. Noble gas isotopic composition of the clinopyroxene megacryst reveals that the mantle source beneath the Kuandian area has an MORB-like reservoir with 3He/4He ratio of ～10 Ra (Ra: atmospheric 3He/4He ratio) and 40Ar/36Ar ratio of 345.6. The lherzolite xenoliths possess moderate 3He/4He ratios of 2.59-4.53 Ra, reflecting the loss of primary helium during rock deformation or metasomatism caused by enriched mantle fluids during the up-lifting. The alkali volcanics have very low 3He/4He ratios (0.47-0.61 Ra), indicating a contribution of radiogenic 4He, probably having resulted from crust contamination. Most of the samples have excess 21Ne and 22Ne as compared with atmospheric neon, but Kr and Xe isotopic compositions are indistinguishable from atmospheric values within uncertainties with only individual samples having excess 129Xe, 134Xe and 136Xe.
文摘The fluid compositions of Cenozoic alkali basalts in eastern China have been determined by the pyrolysis MS method, meanwhile the carbon and oxygen isotopic compositions of CO 2 released from these samples at different heating temperatures have been analyzed by the vacuum step heating method. The data show the volatile heterogeneity in upper mantle sources and different evolution trends of alkali basaltic magmas in eastern China, and these alkali basaltic magmas may be generated in the oxidizing milieu, as compared with mantle derived xenoliths in these alkali basalts, and exotic volatile components were mixed into these magmas in the process of their formation and development.
文摘The Zarqa-Ma’in basalt (MB) occurs near a plateau basalt (wadi fills) covering about 15 km2 of Makawir, Ataruz, and Hammat um Hasana cone areas in central Jordan. The tectonic evolution occurred through intraplate volcanism and erupted through fissure systems along the Dead Sea, transforming the fault during Miocene to Pleistocene period. Three stages of eruption of MB have been recorded during Pleistocene from 6 to 0.6 Ma. The petrographic analyses data show that the MB rocks are composed of plagioclase, olivine, pyroxene, and magnetite, including secondary minerals calcite, iddingsite, serpentine, and zeolite. Furthermore, the MB rocks have narrow ranges of major and trace element concentrations, and are of under saturated silica type and belong to sodic alkaline magma series. The geochemical characteristics of MB indicate that MB was derived from a slightly fractionated magma as reflected by its high MgO (6.3 - 11.7 ppm) concentration with Mg number from 0.41 to 0.61, low silica content (40.83 - 47.55 wt%), and high Cr and Ni concentrations (115 - 475 and 105 - 553 ppm, respectively). This basalt exhibited low degree of partial melting (10%) for garnet peridotite mantle source. The model mineral fractionation showed that the MB could be fractionated to clinopyroxene, orthopyroxene, olivine, and plagioclase.
文摘The main objective of this study is to examine the possibility of using fresh basalt powder in the preparation of geopolymer pastes. Four NaOH concentrations of 2.5, 5, 7.5 and 10 M were used to alkali activation of basalt. In addition, effect of curing temperature at ambient, 45°C and 65°C were studied. The geopolymer pastes were investigated using FTIR, XRD and SEM-EDS techniques as well as compressive strength up to 90 days. The results were shown the compressive strength of prepared geopolymer increased with concentration of alkali activator up to 90 days. On the other hand, the compressive strength of prepared geopolymer pastes were improved with increased curing temperature. The results showed that there was a change in the chemical and mineral structure, due to the reaction of the sodium hydroxide with the different minerals of the basalt. In addition, the Na/Al and Si/Al ratios were completely different from that of the raw basalt. The geopolymerization reactions occurred at the surface basalt and the unreacted basalt particles actually play a supporting role in the geopolymer properties.
基金This paper represents an outcome of a project supported by the National Natural Science Fundation of China (No. 49173167)
文摘The basalt terrain of the Neogene Huangguoshan and. Guiwu Formations of eastern Anhui on the east side of the Tancheng-Lujiang fault belt is one of a few Cenozoic basalt terrains in eastern China for which detailed geochemical study has not been conducted. This paper reports the abundances of major elements and more than 20 trace elements (including REE) of 22 samples and the Nd, Sr and Pb isotopic compositions of 11 samples from the eastern Anhui basalt terrain, thus more or less systematically revealing the geochemical characteristics of this continental basalt suite. The paper discusses the origin of the basalt suite and the character and process of its mantle source. The basalt suite was derived from a heterogeneous continental lithospheric mantle with end members characteristic of the EMI-type oceanic basalt mantle, which was affected by mantle metasomatism (or enrichment of trace elements) and was characterized by a multi-stage evolution under open conditions.
文摘Al Azraq Al Shamali (AZS) basaltic rocks were investigated aiming to understand their mineralogy, petrography and geochemistry features, and to achieve that a total of sixteen representative rock samples were selected for both geochemical and petrographic analysis from several sites in the study area. Petrographic characteristics were analyzed by optical microscopy after preparation thin sections for representative rock samples, which show that all basalt samples have minerals comprising: olivine, plagioclase (labradorite), clinopyroxene (augite), opaque’s and some secondary minerals such as Iddingsite, however, the proportions of each mineral vary between samples. Normative mineralogy by using CIPW Norm showed that AZS basalt samples dominated by olivine, Diopside, and nepheline, and AZS basalt can be normatively classified as alkali olivine basalt. Some textures that may be evident on microscopic examination such as porphyritic, glomeroporphyritic, vesicular, intergranular, and ophitic to sub-ophitic texture. X-Ray Fluorescence was used for whole rock major elements analysis (SiO<sub>2</sub>, TiO<sub>2</sub>, Al<sub>2</sub>O<sub>3</sub>, Fe<sub>2</sub>O<sub>3</sub>, MnO, MgO, CaO, Na<sub>2</sub>O, K<sub>2</sub>O and P<sub>2</sub>O<sub>5</sub> in wt%) and trace element (V, Cr, Co, Ni, Rb, Sr, Y, Zr, Nb, Ce, Nd and Ba in ppm). Geochemical analysis reveal that the basalt is alkaline and includes into Sodic series. AZS basalt are produced under-saturated within intraplate continental environment. The normalized trace element diagrams suggest that the AZS product of the asthenosphere part of the mantle at >100 km depth. Furthermore, the data of studied samples suggest that these rocks evolved from a melt formed by low degrees of partial melting. Also the geochemical variation trends of (AZS) basaltic samples supposing that the composition of these basalt have been influenced by fractional crystallization, without clear evidences for crustal contamination.
基金financial supported by the National Natural Science Foundation of China (Nos. 41276047, 41030853, 41572207, 41440041)the Special and Frontier Foundation for the Twelve Five Plan of the China Ocean Mineral Resources Research and Development Association (No. DY125-22-QY-21)
文摘Two kinds of basalts with different chemical compositions were obtained in the Sanshui Basin,they share the same eruption period. Although they have significant differences in major and trace element concentrations,their isotopic ratios suggest a similar magma source. Based on mineral geochemical analysis,orthopyroxene with reaction rim and zoned clinopyroxene are observed in Zidong(ZD)basalts,but not found in Wangjiegang(WJG) basalts. Linear scanning of these minerals suggests compositional variation between within-plate tholeiite and within-plate alkali-basalt. Presence of a doublelayer magma chamber under the Sanshui Basin,and occurrence of magma mixing between upper and lower chambers is proposed. This magma mixing leads to different chemical composition and mineral constitution of two kinds of basalts,as well as reaction rim and compositional variation of minerals in ZD basalts.
文摘This research was conducted to investigate the mineralogy, petrography, geochemistry and petrogensis of the basaltic flows in Jurf Ed Darawish (JDB) area of central Jordan. Sexton representative basalt rock samples were selected from the studied JDB outcrops. Modally, JDB consists of plagioclase, olivine, pyroxene (diopside), opaque’s, calcite and iddingsite minerals. Petrographically, basalt is holocrystalline, hypidiomorphic fine to medium grained and exhibited aphanitic to porphyritic texture. The common textures of the JDB rock samples were aphanitic, porphyritic, trachytic, glomeroporphyritic, sub ophitic, vesicular, and amygdaloidal. Geochemically, all of the inspected samples of JDB are located within Trachy basalt and plate alkaline basalt. The tectonic setting of JDB was plotted within the calcalkaline basalt and continental basaltic field. The rare-earth elements showed enrichment of the Ba and K, depletion of Ce relative to K, and enrichment of Nb and Pb with depletion of Y and positive Nb, Zr and Ti anomalies. Negative anomalies of Ba, Sr, Ti and P may be attributed to the fractionation of feldspar for Ba and Sr depletion apatite for P depletion. The positive Nb peak conforms to the tertiary as well as to recent continental alkali basalt provinces and acts as an indicator to the JDB product for the lithosphere from upwelling of the asthenosphere mantle.
文摘The study is carried out to list mineralogy and texture of the basalt in Hail region. The basalt flows belong to the Arabian Harrat volcanism. Cenozoic volcanism has produced 13, vast, basaltic fields in western Saudi Arabia, covering a total area of about 100,000 sq. km. The volcanism starts in the late Cretaceous time and continues periodically into the Holocene. The basaltic field presently investigated is known as Harrat Al-Hamad (or Harrat As-Shamah) which lies in northwestern Saudi Arabia, and continues northwards into Jordan. Mineralogical analysis of 20 rock samples indicates that the rocks are products of continental intra-plate magmatism;mostly as coarse-grained silica—under saturated olivine-rich alkali basalt. Mineralogical study shows that rocks are olivine, plagioclase, pyroxene, Nepheline and Opaque minerals. They correspond to alkali olivine basalts. Moreover, the main well-defined texture is intergranular, vesicular and amygdaloidal texture.
