The oxygen and carbon isotopic ratios in human and animal tooth enamel were measured to reconstruct the subsistence patterns on Zhongba Site between 2400 and 4200 aBP.The results indicate that human consumed chiefly C...The oxygen and carbon isotopic ratios in human and animal tooth enamel were measured to reconstruct the subsistence patterns on Zhongba Site between 2400 and 4200 aBP.The results indicate that human consumed chiefly C4 resources,such as millet,and the C3 plants,such as rice and wheat,constituted only a small fraction of the human diets,normally no more than 15%.There are significant differences in food sources between human and pig,and the percentages of C3 plants in pig diets were higher than those in human diets.But theδ13C values of pig partially overlap those of human,demonstrating some similarities in their food sources.The differences in water sources between human and pig are significant.There are significant differences in food and water sources between cattle and deer. This indicates that the two kinds of mammals subsisted in different niches.But theirδ13C values also partially overlap each other,suggesting some similarities in their food sources.There are both signifi- cant differences in meanδ13C andδ18O values between the omnivores,human and pig and the herbi- vores,cattle and deer,implying significant differences in food and water sources between the two categories.During the period the dietary habits of human had not changed,but the pig breeding strategies had changed,from breeding in house to breeding in confinement,and the proportion of C3 plants in pig food increased with time.The scope of human migration had been considerably large by the Warring States because of the development of productive forces.展开更多
Based on the δ13C and δ18O fluctuation of lacustrine carbonate, CaCO3 content and sporopollen data, a palaeoclimatic history of Bosten Lake during the Holocene has been outlined, several stages of climatic changes a...Based on the δ13C and δ18O fluctuation of lacustrine carbonate, CaCO3 content and sporopollen data, a palaeoclimatic history of Bosten Lake during the Holocene has been outlined, several stages of climatic changes are divided, and the following result es are obtained: (1) Palaeoclimatic changes revealed by carbonate isotope around Bosten Lake are basically identical with that revealed by other geological records in Xinjiang. Environmental changes presented apparent Westlies Style model: during cold period, relative humidity increased, δ18O, δ13C and CaCO3 appeared low; but in warm periods, the dry regime aggravated. (2) The temperature reflected by δ18O exist evident features being increase in the late period during the Holocene. Together with the δ13C, pollen and CaCO3 analyses, several cold and warm phases which are of broad regional significance can be identified. The warm peaks occurred at about 11.0 ka B.P., 9.4 ka B.P., 7.5 ka B.P., 5.0 ka B.P., 3.0 ka B.P. and 2.0 ka B.P.; the cold peaks at 11.5 ka B.P., 10.5 ka B.P., 8.8 ka B.P., 5.5 ka B.P., 3.3 ka B.P., 2.2 ka B.P. and 1.5 ka B.P.. (3) Several climatic events with the nature of “abrupt climatic changes” are revealed in the periods of 11.0 ka B.P.-10.5 ka B.P., 9.4 ka B.P.-8.8 ka B.P., 5.5 ka B.P.-5.0 ka B.P. and 2.0 ka B.P.-1.5 ka B.P.. (4) The results show that carbonate isotopic record of lacustrine sediment in arid area is very sensitive to climatic changes, and may be play a very important role in understanding the features and mechanism of palaeoclimatic changes.展开更多
CO2-rich cold springs occur near the active volcanoes at Wudalianchi （五大连池）, Northeast China. The springs are rich in CO2, with HCO3-as the predominant anion and have elevated contents of total dissolved solid ...CO2-rich cold springs occur near the active volcanoes at Wudalianchi （五大连池）, Northeast China. The springs are rich in CO2, with HCO3-as the predominant anion and have elevated contents of total dissolved solid （TDS） （〉1 000 mg/L）, Fe^2＋ （〉20 mg/L）, Sr （〉1 mg/L）, and dissolved Si （〉20 mg/L）. The compositions of escaped and dissolved gases of the springs are similar. The δ^13C values of escaped gases and dissolved gases in mineral springs at Wudalianchi vary from -8.77‰ to -4.53‰ and -8.24‰ to -5.26‰, while δ^18O values vary from -10.68‰ to -7.65‰ and -10.30‰ to -8.84‰, respectively, indicating the same upper mantle origin of CO2 of escaped gases and dissolved gases in the springs. Carbon and oxygen isotope fractionations and water-CO2 exchange were weak in the process of groundwater flow. The 4He content exceeds 5 000×10-6 cm^3·STP/mL in escaped gases of the mineral springs, and the 3He/4He ratios of the escaped and dissolved gases vary from 2.64Ra to 3.87Ra and 1.18Ra to 3.30Ra, respectively. It can be postulated that the CO2 of mineral springs deriving from the magma chamber of the upper mantle moves upward to the surface, to increase the content of 4He in the mineral springs and decrease the ratio of 3He/4He. The helium origin of escaped gases in springs can be calculated with the MORB-crust mixing model, but that in the north spring can be better explained with the MORB-crust-air mixing model due to the effect of mixing with surface water. However, dissolved helium in springs, except the north spring, is better explained with the MORB-crust-ASW mixing model.展开更多
In the last ten years, with important discoveries from oil and gas exploration in the Dabashan foreland depression belt in the borderland between Shanxi and Sichuan provinces, the relationship between the formation an...In the last ten years, with important discoveries from oil and gas exploration in the Dabashan foreland depression belt in the borderland between Shanxi and Sichuan provinces, the relationship between the formation and evolution of, and hydrocarbon accumulation in, this foreland thrust belt from the viewpoint of basin and oil and gas exploration has been studied. At the same time, there has been little research on the origin of fluids within the belt. Based on geochemical system analysis including Z values denoting salinity and research on δ13C, δ18O and S7Sr/S6Sr isotopes in the host rocks and veins, the origin of paleofluids in the foreland thrust belt is considered. There are four principal kinds of paleofluid, including deep mantle-derived, sedimentary, mixed and meteoric. For the deep mantle-derived fluid, the δ13C is generally less than -5.0‰PDB, δ18O less than -10.0‰PDB, Z value less than 110 and 87Sr/86Sr less than 0.70600; the sedimentary fluid is mainly marine carbonate- derived, with the δ13C generally more than -2.0‰PDB, 18δO less than -10.0‰PDB, Z value more than 120 and STSr/S6Sr ranging from 0.70800 to 0.71000; the mixed fluid consists mainly of marine carbonate fluid （including possibly a little mantle-derived fluid or meteoric water）, with the j13C generally ranging from -2.0‰ to -8.0‰PDB, δ18O from -10.0‰ to -18.0‰ PDB, Z value from 105 to 120 and 87Sr/86Sr from 0.70800 to 0.71000; the atmospheric fluid consists mainly of meteoric water, with the δ13C generally ranging from 0.0‰ to -10.0‰PDB, δ18O less than -8.0%rPDB, Z value less than 110 and 87Sr/86Sr more than 0.71000. The Chengkou fault belt encompasses the most complex origins, including all four types of paleofluid; the Zhenba and Pingba fault belts and stable areas contain a simple paleofluid mainly of sedimentary type; the Jimingsi fault belt contains mainly sedimentary and mixed fluids, both consisting of sedimentary fluid and meteoric water. Jurassic rocks of the foreland depression belt contain mainly 展开更多
The origin of grain dolomite in M55 Member of Ordovician Majiagou Formation in northwestern Ordos Basin was studied by geochemical and petrological tests on core samples.Observation of cores,thin sections and casting ...The origin of grain dolomite in M55 Member of Ordovician Majiagou Formation in northwestern Ordos Basin was studied by geochemical and petrological tests on core samples.Observation of cores,thin sections and casting thin sections,analysis of cathodoluminescence,X-ray diffraction,microscopic sampling of trace elements,laser samplingδ18O andδ13C,and fluid inclusion homogenization temperature were conducted.The results show that the dolomite is the product of recrystallization of micritic to crystal powder dolomite rather than the product of dolomitization of grain limestone.In the spherical grains are residual gypsum and halite pseudo crystals identical with those in the host micritic dolomite.The spherical particles of dolomite has similar trace elements andδ18O andδ13C characteristics to micritic dolomite.Furthermore,Mn/Sr ratio of the fine-medium dolomite between the dolomite grains is about 5-8,while Mn/Sr ratios of calcite in limestone,micritic dolostone in micritic dolomite,and micritic and powdery dolomite are about 0-2,indicating that the dolomite experienced strong diagenesis.Homogenization temperature of inclusions of fine-medium dolomite is about 148.19°C,higher than that of inclusions in micritic to crystal powder dolomite(about 122.60°C),which also supports the conclusion that the grain dolomite experienced burial diagenesis and negative shift ofδ18O andδ13C.Theδ18O,δ13C values of micritic to crystal powder dolomite match with the negative migration,but those of calcite in limestone don’t.It is of great significance to elucidate the genesis of"dolomite recrystallization"for the prediction of such dolomite reservoirs.展开更多
The influence of metal cations on 13C-18O bonds in carbonates is still under debate. This paper used ab initio method to investigate this kind of influence of Mg2+, Fe2+ and Zn2+ cations on 13C-18O bonds in precipitat...The influence of metal cations on 13C-18O bonds in carbonates is still under debate. This paper used ab initio method to investigate this kind of influence of Mg2+, Fe2+ and Zn2+ cations on 13C-18O bonds in precipitated aragonite, calcite and dolomite. The polynomials of Δ47 and reduced partition function ratios (RPFRs) for 13/12C, 14/12C and 18/16O of these minerals were given within temperatures ranging from 260 to 1500 K. We found that these cations significantly decreased the Δ47 values at the level of 10-3 - 10-2 per mil, comparing with pure crystals;and that if the Δ47 values were used to reconstruct the temperatures Ts, the deviation of T was about 7.2°C for, for instance, zinc-enriched aragonite, as discussed in our paper. It was suggested that due to such influence, researchers would better use a proper thermometer according to the main impurity metal cations in carbonates. We also found that according to the probability theory, the theoretical value of the influence of phosphoric acid on Δ47 of CO2 degassed from different carbonates was zero.展开更多
基金Supported by the Key Project of the National Natural Science Foundation of China(Grant No.90411015)the University Doctoral Foundation(Grant No.20050284011)+2 种基金the Foundation of Important Basic Research at Nanjing University(Grant No.0209005206)the Open Foundation of the State Key Laboratory of Loess and Quaternary Geology from the Institute of Earth Environment,CAS(Grant No.SKLLQG0503)the Physical Geography of"985"Items and the Test Foundation of Modern Analyses Center of Nanjing University(Grant No.0209001309)
文摘The oxygen and carbon isotopic ratios in human and animal tooth enamel were measured to reconstruct the subsistence patterns on Zhongba Site between 2400 and 4200 aBP.The results indicate that human consumed chiefly C4 resources,such as millet,and the C3 plants,such as rice and wheat,constituted only a small fraction of the human diets,normally no more than 15%.There are significant differences in food sources between human and pig,and the percentages of C3 plants in pig diets were higher than those in human diets.But theδ13C values of pig partially overlap those of human,demonstrating some similarities in their food sources.The differences in water sources between human and pig are significant.There are significant differences in food and water sources between cattle and deer. This indicates that the two kinds of mammals subsisted in different niches.But theirδ13C values also partially overlap each other,suggesting some similarities in their food sources.There are both signifi- cant differences in meanδ13C andδ18O values between the omnivores,human and pig and the herbi- vores,cattle and deer,implying significant differences in food and water sources between the two categories.During the period the dietary habits of human had not changed,but the pig breeding strategies had changed,from breeding in house to breeding in confinement,and the proportion of C3 plants in pig food increased with time.The scope of human migration had been considerably large by the Warring States because of the development of productive forces.
文摘Based on the δ13C and δ18O fluctuation of lacustrine carbonate, CaCO3 content and sporopollen data, a palaeoclimatic history of Bosten Lake during the Holocene has been outlined, several stages of climatic changes are divided, and the following result es are obtained: (1) Palaeoclimatic changes revealed by carbonate isotope around Bosten Lake are basically identical with that revealed by other geological records in Xinjiang. Environmental changes presented apparent Westlies Style model: during cold period, relative humidity increased, δ18O, δ13C and CaCO3 appeared low; but in warm periods, the dry regime aggravated. (2) The temperature reflected by δ18O exist evident features being increase in the late period during the Holocene. Together with the δ13C, pollen and CaCO3 analyses, several cold and warm phases which are of broad regional significance can be identified. The warm peaks occurred at about 11.0 ka B.P., 9.4 ka B.P., 7.5 ka B.P., 5.0 ka B.P., 3.0 ka B.P. and 2.0 ka B.P.; the cold peaks at 11.5 ka B.P., 10.5 ka B.P., 8.8 ka B.P., 5.5 ka B.P., 3.3 ka B.P., 2.2 ka B.P. and 1.5 ka B.P.. (3) Several climatic events with the nature of “abrupt climatic changes” are revealed in the periods of 11.0 ka B.P.-10.5 ka B.P., 9.4 ka B.P.-8.8 ka B.P., 5.5 ka B.P.-5.0 ka B.P. and 2.0 ka B.P.-1.5 ka B.P.. (4) The results show that carbonate isotopic record of lacustrine sediment in arid area is very sensitive to climatic changes, and may be play a very important role in understanding the features and mechanism of palaeoclimatic changes.
基金supported by the National Natural Science Foundation of China(Nos.40425001,40602031,40830748),and Russian Fund for Basic Research
文摘CO2-rich cold springs occur near the active volcanoes at Wudalianchi （五大连池）, Northeast China. The springs are rich in CO2, with HCO3-as the predominant anion and have elevated contents of total dissolved solid （TDS） （〉1 000 mg/L）, Fe^2＋ （〉20 mg/L）, Sr （〉1 mg/L）, and dissolved Si （〉20 mg/L）. The compositions of escaped and dissolved gases of the springs are similar. The δ^13C values of escaped gases and dissolved gases in mineral springs at Wudalianchi vary from -8.77‰ to -4.53‰ and -8.24‰ to -5.26‰, while δ^18O values vary from -10.68‰ to -7.65‰ and -10.30‰ to -8.84‰, respectively, indicating the same upper mantle origin of CO2 of escaped gases and dissolved gases in the springs. Carbon and oxygen isotope fractionations and water-CO2 exchange were weak in the process of groundwater flow. The 4He content exceeds 5 000×10-6 cm^3·STP/mL in escaped gases of the mineral springs, and the 3He/4He ratios of the escaped and dissolved gases vary from 2.64Ra to 3.87Ra and 1.18Ra to 3.30Ra, respectively. It can be postulated that the CO2 of mineral springs deriving from the magma chamber of the upper mantle moves upward to the surface, to increase the content of 4He in the mineral springs and decrease the ratio of 3He/4He. The helium origin of escaped gases in springs can be calculated with the MORB-crust mixing model, but that in the north spring can be better explained with the MORB-crust-air mixing model due to the effect of mixing with surface water. However, dissolved helium in springs, except the north spring, is better explained with the MORB-crust-ASW mixing model.
基金supported by the National Basic Research Project("973" Project,Grant No. 2006CB202305) and SINOPEC
文摘In the last ten years, with important discoveries from oil and gas exploration in the Dabashan foreland depression belt in the borderland between Shanxi and Sichuan provinces, the relationship between the formation and evolution of, and hydrocarbon accumulation in, this foreland thrust belt from the viewpoint of basin and oil and gas exploration has been studied. At the same time, there has been little research on the origin of fluids within the belt. Based on geochemical system analysis including Z values denoting salinity and research on δ13C, δ18O and S7Sr/S6Sr isotopes in the host rocks and veins, the origin of paleofluids in the foreland thrust belt is considered. There are four principal kinds of paleofluid, including deep mantle-derived, sedimentary, mixed and meteoric. For the deep mantle-derived fluid, the δ13C is generally less than -5.0‰PDB, δ18O less than -10.0‰PDB, Z value less than 110 and 87Sr/86Sr less than 0.70600; the sedimentary fluid is mainly marine carbonate- derived, with the δ13C generally more than -2.0‰PDB, 18δO less than -10.0‰PDB, Z value more than 120 and STSr/S6Sr ranging from 0.70800 to 0.71000; the mixed fluid consists mainly of marine carbonate fluid （including possibly a little mantle-derived fluid or meteoric water）, with the j13C generally ranging from -2.0‰ to -8.0‰PDB, δ18O from -10.0‰ to -18.0‰ PDB, Z value from 105 to 120 and 87Sr/86Sr from 0.70800 to 0.71000; the atmospheric fluid consists mainly of meteoric water, with the δ13C generally ranging from 0.0‰ to -10.0‰PDB, δ18O less than -8.0%rPDB, Z value less than 110 and 87Sr/86Sr more than 0.71000. The Chengkou fault belt encompasses the most complex origins, including all four types of paleofluid; the Zhenba and Pingba fault belts and stable areas contain a simple paleofluid mainly of sedimentary type; the Jimingsi fault belt contains mainly sedimentary and mixed fluids, both consisting of sedimentary fluid and meteoric water. Jurassic rocks of the foreland depression belt contain mainly
基金Supported by the China National Science and Technology Major Project(2016ZX05050).
文摘The origin of grain dolomite in M55 Member of Ordovician Majiagou Formation in northwestern Ordos Basin was studied by geochemical and petrological tests on core samples.Observation of cores,thin sections and casting thin sections,analysis of cathodoluminescence,X-ray diffraction,microscopic sampling of trace elements,laser samplingδ18O andδ13C,and fluid inclusion homogenization temperature were conducted.The results show that the dolomite is the product of recrystallization of micritic to crystal powder dolomite rather than the product of dolomitization of grain limestone.In the spherical grains are residual gypsum and halite pseudo crystals identical with those in the host micritic dolomite.The spherical particles of dolomite has similar trace elements andδ18O andδ13C characteristics to micritic dolomite.Furthermore,Mn/Sr ratio of the fine-medium dolomite between the dolomite grains is about 5-8,while Mn/Sr ratios of calcite in limestone,micritic dolostone in micritic dolomite,and micritic and powdery dolomite are about 0-2,indicating that the dolomite experienced strong diagenesis.Homogenization temperature of inclusions of fine-medium dolomite is about 148.19°C,higher than that of inclusions in micritic to crystal powder dolomite(about 122.60°C),which also supports the conclusion that the grain dolomite experienced burial diagenesis and negative shift ofδ18O andδ13C.Theδ18O,δ13C values of micritic to crystal powder dolomite match with the negative migration,but those of calcite in limestone don’t.It is of great significance to elucidate the genesis of"dolomite recrystallization"for the prediction of such dolomite reservoirs.
文摘The influence of metal cations on 13C-18O bonds in carbonates is still under debate. This paper used ab initio method to investigate this kind of influence of Mg2+, Fe2+ and Zn2+ cations on 13C-18O bonds in precipitated aragonite, calcite and dolomite. The polynomials of Δ47 and reduced partition function ratios (RPFRs) for 13/12C, 14/12C and 18/16O of these minerals were given within temperatures ranging from 260 to 1500 K. We found that these cations significantly decreased the Δ47 values at the level of 10-3 - 10-2 per mil, comparing with pure crystals;and that if the Δ47 values were used to reconstruct the temperatures Ts, the deviation of T was about 7.2°C for, for instance, zinc-enriched aragonite, as discussed in our paper. It was suggested that due to such influence, researchers would better use a proper thermometer according to the main impurity metal cations in carbonates. We also found that according to the probability theory, the theoretical value of the influence of phosphoric acid on Δ47 of CO2 degassed from different carbonates was zero.
