共查询到20条相似文献,搜索用时 31 毫秒
1.
The Luliang and Baoshan basins are two small ba- sins in Yunnan Province. In the recent ten years or so, there have been found a number of natural gas pools of commercial importance in the two basins. Although the gas pools are small in size, the natural … 相似文献
2.
This paper presents gas compositions and H-, O-isotope compositions of sulfide- and quartz-hosted fluid inclusions, and S-, Pb-isotope compositions of sulfide separates collected from the principal Stage 2 ores in Veins 3 and 210 of the Jinwozi lode gold deposit, eastern Tianshan Mountains of China. Fluid inclusions trapped in quartz and sphalerite are dominantly primary. H-and O-isotopic compositions of pyrite-hosted fluid inclusions indicate two major contributions to the ore-forming fluid that include the degassed magma and the meteoric-derived but rock 18O-buffered groundwater. However, H- and O-isotopic compositions of quartz-hosted fluid inclusions essentially suggest the presence of groundwater. Sulfide-hosted fluid inclusions show considerably higher abundances of gaseous species CO2, N2, H2S, etc. than quartz-hosted ones. The linear trends among inclusion gaseous species reflect the mixing tendency between the gas-rich magmatic fluid and the groundwater. The relative enrichment of gaseous species in sulfide-hosted fluid inclusions, coupled with the banded ore structure indicating alternate precipitation of quartz with sulfide minerals, suggests that the magmatic fluid has been inputted to the ore-forming fluid in pulsation. Sulfur and lead isotope compositions of pyrite and galena separates indicate an essential magma derivation for sulfur but the multiple sources for metallic materials from the mantle to the bulk crust. 相似文献
3.
This paper presents gas compositions and H-, O-isotope compositions of sulfide- and quartz-hosted fluid inclusions, and S-, Pb-isotope compositions of sulfide separates collected from the principal Stage 2 ores in Veins 3 and 210 of the Jinwozi lode gold deposit, eastern Tianshan Mountains of China. Fluid inclusions trapped in quartz and sphalerite are dominantly primary. H-and O-isotopic compositions of pyrite-hosted fluid inclusions indicate two major contributions to the ore-forming fluid that include the degassed magma and the meteoric-derived but rock 18O-buffered groundwater. However, H- and O-isotopic compositions of quartz-hosted fluid inclusions essentially suggest the presence of groundwater. Sulfide-hosted fluid inclusions show considerably higher abundances of gaseous species CO 2, N 2, H 2S, etc. than quartz-hosted ones. The linear trends among inclusion gaseous species reflect the mixing tendency between the gas-rich magmatic fluid and the groundwater. The relative enrichment of gaseous species in sulfide-hosted fluid inclusions, coupled with the banded ore structure indicating alternate precipitation of quartz with sulfide minerals, suggests that the magmatic fluid has been inputted to the ore-forming fluid in pulsation. Sulfur and lead isotope compositions of pyrite and galena separates indicate an essential magma derivation for sulfur but the multiple sources for metallic materials from the mantle to the bulk crust. 相似文献
4.
We have combined the analytical data of the carbon isotope distribution pattern, R/Ra and CH4/3He values of abiogenic and biogenic (referring to the thermogenic and bacterial or microbial) alkane gases in China with those of alkane gases from USA, Russia, Germany, Australia and other countries. Four discrimination criteria are derived from this comparative study: 1) Carbon isotopic composition is generally greater than -30‰ for abiogenic methane and less than -30‰ for biogenic methane; 2) Abiogenic alkane gases have a carbon isotopic reversal trend (δ 13C1> δ 13C2> δ 13C3> δ 13C4) with δ 13C1>-30‰ in general; 3) Gases with R/Ra >0.5 and δ 13C11 δ 13C2>0 are of abiogenic origin; 4) Gases (meth- ane) with CH4/3He≤106 are of abiogenic origin, whereas gases with CH4/3He≥1011 are of biogenic origin. 相似文献
5.
Carbon isotope ratios ( δ
13C) of 89 C 4 plant samples were determined from the loess area in North China. δ
13C values vary between −10.5‰ and −14.6‰ with a mean of −12.6‰. Along a precipitation gradient from the semi-moist area to
the semiarid area, then to the arid area, the δ
13C values of C 4 plants show a slight decreasing trend. The δ
13C values of C 4 plants in the dry season are found lower than those in the wet season. These trends are opposite to those observed for C 3 species. 相似文献
6.
This paper discusses the kinetic fractionation, composition and distribution characteristics of carbon and hydrogen isotopes for various alkane gases formed in different environments, by different mecha- nisms and from different sources in nature. It is demonstrated that the biodegradation or thermode- gradation of complex high-molecule sedimentary organic material can form microbial gas or thermogenic gas. The δ 13C1 value ranges from -110‰ to -50‰ for microbial gases but from -50‰ to -35‰ (even heavier) f... 相似文献
7.
Since the 1990s, interest in the magmatic fluids and their relation to mineralization has been re-aroused[1—6]. Studies on stable isotopes of low-sulfidation deposits commonly show the predominance of meteoric water[7]. Paradoxically, the evidence for me… 相似文献
8.
13C of 367 C 3 herbaceous plants was measured in loess area in northern China. Their δ 13C values vary between −21.7%. and −30.0%., with a mean of −26.7%.. In the center of Loess Plateau (semimoist area) with annual
precipitation of 400–600 mm, the δ 13
C values of C 3 herbaceous plants range from −24.4%. to −28.5%., with a mean of −27.5%.. In the west of Loess Plateau (semiarid and arid
area) with annual precipitation less than 400 mm, they range between −21.7%. and −30.0%., with a mean of −26.2%.. Annual precipitation
is the main factor that makes δ 13C values of C 3 herbaceous plants in the west greater than those in the central Loess Plateau. The composition of δ 13C in C 3 plants increases with deceasing annual precipitation, and the mean change is −49%./100 mm. 相似文献
9.
China’s widespread marine carbonate rock series are mostly characterized by intensive thermal evolu- tion and low abundance of organic matter, especially the Lower Paleozoic carbonate rocks have experienced multi-episodes of tectonics and prolonged history of thermal evolution, thus making it more complicatedethe development and distribution of hydrocar- bon-source rocks reflected in the sedimentary, bio- logical and geochemical facies. Consequently, it seems much less powerful to assess the … 相似文献
10.
The distribution of two formation pathways of biogenic methane, acetate fermentation and reduction of CO2, has been extensively studied. In general, CO2 reduction is the dominate pathway in marine envi- ronment where acetate is relatively depleted because of SRB consuming. While in terrestrial freshwater or brackish environment, acetate fermentation is initially significant, but decreases with increasing buried depth. In this paper, character of biogenic gases is profiled in the XS3-4 well of the Sebei 1 gas field in the Sanhu depression, Qaidam Basin. It indicates that those two pathways do not change strictly with increasing buried depth. CO2 reduction is important near the surface (between 50 m and 160 m), and at the mesozone (between 400 and 1650 m). While acetate fermentation is the primary pathway at two zones, from 160 to 400 m and from 1650 to 1700 m. δ 13C of methane generated in those two acetate fermentation zones varies greatly, owing to different sediment circumstances. At the sec- ond zone (160-400 m), δ 13C1 ranges from ?65‰ to ?30‰ (PDB), because the main deposit is mudstone and makes the circumstance confined. At the fourth zone of the well bottom (1650-1700 m), δ 13C1 is lighter than ?65‰ (PDB). Because the deposit is mainly composed of siltstone, it well connects with outer fertile groundwater and abundant nutrition has supplied into this open system. The high con- centration of acetate is a forceful proof. δ 13C of methane would not turn heavier during fermentation, owing to enough nutrition supply. In spite of multi-occurrence of acetate fermentation, the commercial gas accumulation is dominated by methane of CO2-reduction pathway. A certain content of alkene gases in the biogenic gases suggests that methanogensis is still active at present. 相似文献
11.
We describe analytical details and uncertainty evaluation of a simple technique for the measurement of the carbon isotopic
composition of CO 2 in volcanic plumes. Data collected at Solfatara and Vulcano, where plumes are fed by fumaroles which are accessible for direct
sampling, were first used to validate the technique. For both volcanoes, the plume-derived carbon isotopic compositions are
in good agreement with the fumarolic compositions, thus providing confidence on the method, and allowing its application at
volcanoes where the volcanic component is inaccessible to direct sampling. As a notable example, we applied the same method
to Mount Etna where we derived a δ 13C of volcanic CO 2 between −0.9 ± 0.27‰ and −1.41 ± 0.27‰ (Bocca Nuova and Voragine craters). The comparison of our measurements to data reported
in previous work highlights a temporal trend of systematic increase of δ 13C values of Etna CO 2 from ~ −4‰, in the 1970’s and the 1980’s, to ~ −1‰ at the present time (2009). This shift toward more positive δ 13C values matches a concurrent change in magma composition and an increase in the eruption frequency and energy. We discuss
such variations in terms of two possible processes: magma carbonate assimilation and carbon isotopic fractionation due to
magma degassing along the Etna plumbing system. Finally, our results highlight potential of systematic measurements of the
carbon isotopic composition of the CO 2 emitted by volcanic plumes for a better understanding of volcanic processes and for improved surveillance of volcanic activity. 相似文献
12.
The Raman spectrograms of hydrocarbon standard samples show that: (1) the Raman spectrogram of normal paraffin has very strong peaks of methyl and methylene (from 2700 cm-1 to 2970 cm-1); (2) branch methyl has the particular peak of 748 cm-1±; (3) six cyclic has the particular peak of 804 cm-1±; (4) phenyl has two particular peaks of 988 cm-1± and 3058 cm-1± and the 988 cm-1± peak is stronger than the 3058 cm-1± peak; and (5) hexene has three alkenyl spectrum peaks of 1294 cm-1±, 1635 cm-1± and 2996 cm-1±, with the 1635 cm-1± peak being the strongest, showing that the number of carbon in hy-drocarbon does not affect its Raman spectrogram, and the hydrocarbon molecular structure and base groups affect its Raman spectrogram, the same hydrocarbons (such as normal paraffin) have the same Raman spectrogram; the types (such as CH4, C2H6, C3H8) and the content of hydrocarbon in oil inclu-sions are not estimated by their characteristic Raman peaks. According to the Raman spectrograms of hydrocarbon compositions, the Raman spectrogram of hydrocarbon inclusion can be divided into five types: saturated hydrocarbon Raman spectrogram, fluoresce Raman spectrogram, saturated hydro-carbon bitumen Raman spectrogram, bitumen Raman spectrogram, and ethane Raman spectrogram. And according to the characteristics of Raman spectrogram, hydrocarbon inclusions can be divided into five types: saturated hydrocarbon inclusion, less saturated hydrocarbon (oil or gas) inclusion, saturated hydrocarbon bitumen inclusion, bitumen inclusion, and methane water inclusion. 相似文献
13.
An igneous intrusion of 94m thick was discovered intruding into the Silurian sandstone from Tazhong 18 Well. The petroleum
previously preserved in the Silurian sandstone reservoir was altered into black carbonaceous bitumen by abnormally high heat
stress induced by the igneous intrusion. The reflectance of the carbonaceous bitumen reaches as high as 3.54%, indicating
that the bitumen had evolved into a high thermal evolution level. Similar to the Silurian samples from the neighboring Tazhong
11, Tazhong 12, Tazhong 45 and Tazhong 47 wells, the distribution of C 27, C 28 and C 29 steranes of the carbonaceous bitumen is still “V”-shaped and can still be employed as an efficient parameter in oil source
correlation. The “V”-shaped distribution indicates that the hydrocarbons from the Tazhong 18 and the neighboring wells were
all generated from the Middle-Upper Ordovician hydrocarbon source rocks. However, the oil source correlation parameters associated
with and terpanes had been changed greatly by the high heat stress and can no longer be used in oil source correlation. The
δ
13C values of the petroleum from the neighboring wells are between −32.53%. and −33.37%., coincident with those of the Paleozoic
marine petroleum in the Tarim Basin. However, the δ
13C values of the carbonaceous bitumen from the Tazhong 18 Well are between −27.18%. and −29.26%., isotopically much heavier
than the petroleum from the neighboring wells. The content of light hydrocarbons ( nC 14− nC 20) of the saturated hydrocarbon fraction in the carbonaceous bitumen is extremely higher than the content of heavy hydrocarbons.
The light/heavy hydrocarbon ratios (Σ nC 21
−/Σ nC 22
+ are between 4.56 and 39.17. In the saturated fraction, the even numbered hydrocarbons are predominant to the odd numbered,
and the OEP (Odd to Even Predominance) values are between 0.22 and 0.49. However, the content of light hydrocarbons in the
petroleum from the neighboring wells is relatively low and the content of the even numbered hydrocarbons is almost equal to
that of the odd numbered. Compared with the samples from the neighboring wells, the abundance of non-alkylated aromatic hydrocarbons,
such as phenanthrenes, and polycyclic aromatic hydrocarbons (PAHs), such as fluoranthane, pyrene, benzo[a]anthracene and benzofluoranthene,
are relatively high.
Supported by the National Key Basic Research and Development Project (Grant No. 2005CB422103) 相似文献
14.
The sorption of AuCl 4
−,AuCl 2
− and Au(S 2O 3) 3- on δ-MnO 2 was investigated at pH2–11.6, 0.01 mol/L and 0.1 mol/L NaNO 3 solutions. At pH 4 in two electrolyte strength solutions, Au sorption densities on δ-MnO 2 are 0.18–0.21 and 0.28 μmoL/m 2 for AuCl 4
− and Au(S 2O 3) 2
3-, respectively, and the Au surface coverage is approximate to or lower than 1%. This adsorption of the two Au complexes decreases
as the solution pH increases, which conforms to the sorption regularity of the anion on δ-MnO 2. The Au sorption decreases in the sequence of Au(S 2O 3) 2
3- >AuCl 4
− >AuC1 2
−. The intrinsic equilibrium constants (log K
int) of the three Au complexes are 1.17–2.7, much higher than those of Cu and Cd. The hydrolysis products of AuCl 4
- are preferentially adsorbed by δ-MnO 2 and the inner-sphere Au-surface complexes are formed on the surface.
Project supported by the National Studying-abroad Foundation, the National Natural Science Foundation of China (Grant No.
49573200) and the Australian Mining Industry. 相似文献
15.
2 and approximately 85% SO 2 of the total sulfur gas. Relative amounts of He, Ar, and N 2 show a distinct hot-spot signature ( ). The δ 13C–CO 2 is approximately −3.6‰ and δ 34S T is approximately +3.3‰. The δD/δ 18O of fumarole H 2O indicates steam separation from local meteoric waters whose estimated minimum mean residence time from 3H analyses is ≤40 years. Fumarolic activity at Alcedo is controlled by a caldera-margin fault containing at least seven hydrothermal
explosion craters, and by an intracaldera rhyolite vent. Two explosion craters which formed in 1993–1994 produce approximately
15 m 3/s of steam, yet discharge temperatures are ≤97°C. Water content of the total gas is 95–97 mol.%, noncondensible gas is 92–98 mol.%
CO 2, and sulfur gas is dominated by H 2S. Relative amounts of He, Ar, and N 2 show extensive mixing between hot spot and air or air-saturated meteoric water components but the average . The δ 13C–CO 2 is approximately −3.5‰ and δ 34S T is approximately −0.8‰. The δD/δ 18O of fumarole steam indicates separation from a homogeneous reservoir that is enriched 3–5‰ in 18O compared with local meteoric water. 3H indicates that this reservoir water has a maximum mean residence time of approximately 400 years and empirical gas geothermometry
indicates a reservoir temperature of 260–320°C. The intracaldera hydrothermal reservoir in Alcedo is probably capable of producing
up to 150 MW; however, environmental concerns as well as lack of infrastructure and power users will limit the development
of this resource.
Received: 19 April 1999 / Accepted: 23 October 1999 相似文献
16.
Despite great achievements in the origins of domestic pigs made by the methods of zooarchaeology and molecular biology, how
to scientifically distinguish the domesticated pigs from wild boars during the early stage of pig domestication is still poorly
understood. Compared to wild boar’s diets which come from the natural environment, the diets of domestic pigs are more easily
influenced by human feeding activities. Therefore, in principle, exploration of the dietary differences among pigs and under-standing
the impact on pig diets fed by humans can have great potential to differentiate between wild boars and domesticated pigs.
To reveal dietary differences among pigs and distinguish the domesticated pigs from wild boars based on comparison with the
diets of humans and other animals, we analyzed the carbon and nitrogen stable isotopes of human bones from Xiaojingshan Site
and animal bones from Yuezhuang Site, both of which belong to Houli Culture in Shandong Province and date to about 8500-7500
years ago. The mean δ 13C value ((−17.8 ± 0.3)‰) and δ 15N value ((9.0±0.6)‰) in human collagen indicate that although millet agriculture began it was not the main subsistence strategy
as millets are typical of C 4 plants and that humans made a living mainly by gathering, hunting or raising some domesticated animals. The δ 13C value (−16.1‰) and δ 15N value (6.9‰) in the bovine suggest that C 3 plants were dominant in its diet with some C 4 plants complemented. The fish has lower δ 13C value (−24.9‰) and higher δ 15N value (8.8‰) than the bovine, which is the characteristic of the isotopic values from Eurasian freshwater fish. Based on
the differences in carbon and nitrogen isotope values, the pigs can be divided into three groups. A group, composed of two
pigs, has low δ 13C values (−18.1‰, −20.0‰) and low δ 15N values (4.7‰, 6.0‰). B group, only one pig, has the highest δ 13C value (−10.6‰) and mediate δ 15N value (6.4‰). As for the C group, also only one pig, low δ 13C value (−19.0‰) and the highest δ 15N value (9.1‰) are observed. Previous studies on the stable isotopes from modern or ancient wild boars’ bones have suggested
that C 3 plants are predominated in their diets and that their δ 15N values are close to those in herbivores and far from those in carnivores. Based on the comparison with the isotope values
from humans, the wild boars and the domestic pigs from Xipo Site in Henan 6000-5500 years ago and Kangjia Site in Shaanxi
4500-4000 years ago, we conclude that A pig group belongs to wild boars while B and C groups can be attributed to domesticated
pigs.
Supported by Max-Planck Society and Chinese Academy of Sciences, Knowledge Innovation Program of the Chinese Academy of Sciences
(Grant No. KJCX3.SYW.N12), National Natural Science Foundation of China (Grant No. 40702003) and President Funding of Graduate
University of Chinese Academy of Sciences 相似文献
17.
Materials of long-term studies of the concentration and distribution of N forms (NH 4+, NO 3−, NO 2−, N org) in precipitation, surface water and groundwater are generalized. Precipitation was found to be the main source of N compounds
input into these waters. The effect of anthropogenic factors is local and does not influence the concentration and distribution
of N forms in most water bodies that serve as wastewater recipients. The N forms dominating in precipitation are NO 3− and N H 4+; N org dominates in most surface water bodies, and NO 3− dominates in groundwater. The median concentrations of N tot in clear surface and subsurface waters are similar. The obtained characteristics of the concentrations and distribution of
N forms in natural waters of Karelia can be used for other water bodies in the humid zone. 相似文献
18.
This study presents baseline data for future geochemical monitoring of the active Tacaná volcano–hydrothermal system (Mexico–Guatemala).
Seven groups of thermal springs, related to a NW/SE-oriented fault scarp cutting the summit area (4,100m a.s.l.), discharge
at the northwest foot of the volcano (1,500–2,000m a.s.l.); another one on the southern ends of Tacaná (La Calera). The near-neutral
(pH from 5.8 to 6.9) thermal ( T from 25.7°C to 63.0°C) HCO 3–SO 4 waters are thought to have formed by the absorption of a H 2S/SO 2–CO 2-enriched steam into a Cl-rich geothermal aquifer, afterwards mixed by Na/HCO 3-enriched meteoric waters originating from the higher elevations of the volcano as stated by the isotopic composition (δD
and δ 18O) of meteoric and spring waters. Boiling temperature fumaroles (89°C at ~3,600m a.s.l. NW of the summit), formed after the
May 1986 phreatic explosion, emit isotopically light vapour (δD and δ 18O as low as −128 and −19.9‰, respectively) resulting from steam separation from the summit aquifer. Fumarolic as well as bubbling
gases at five springs are CO 2-dominated. The δ 13C CO2 for all gases show typical magmatic values of −3.6 ± 1.3‰ vs V-PDB. The large range in 3He/ 4He ratios for bubbling, dissolved and fumarolic gases [from 1.3 to 6.9 atmospheric 3He/ 4He ratio ( R
A)] is ascribed to a different degree of near-surface boiling processes inside a heterogeneous aquifer at the contact between
the volcanic edifice and the crystalline basement ( 4He source). Tacaná volcano offers a unique opportunity to give insight into shallow hydrothermal and deep magmatic processes
affecting the CO 2/ 3He ratio of gases: bubbling springs with lower gas/water ratios show higher 3He/ 4He ratios and consequently lower CO 2/ 3He ratios (e.g. Zarco spring). Typical Central American CO 2/ 3He and 3He/ 4He ratios are found for the fumarolic Agua Caliente and Zarco gases (3.1 ± 1.6 × 10 10 and 6.0 ± 0.9 R
A, respectively). The L/ S (5.9 ± 0.5) and ( L + S)/ M ratios (9.2 ± 0.7) for the same gases are almost identical to the ones calculated for gases in El Salvador, suggesting an
enhanced slab contribution as far as the northern extreme of the Central American Volcanic Arc, Tacaná. 相似文献
19.
Stable carbon and oxygen isotopes have been observed in dinosaur eggshell samples,identified as Macroolithus yaotunensis,collected in two sections of the Nanxiong Basin,Guangdong Province,South China.Multiple positiveδ18O perturbations that occurred during the K/T transition of about 150 ka suggest that there may have been at least three periods of the extreme dry climate with a mean annual air temperature over 27℃.δ13C ranges from -8.37‰ to -11.60‰ of the dinosaur eggshells,added to the metabolic enrichment of 16‰,may indicate that the dinosaurs represented by this type of eggshells probably consumed the plant species of C3 type with the δ13C values of -24.3‰- -27.6‰.Moreover,the trend toward more negative δ13C values of the eggshells during the K/T transition could be an indirect consequence of a lasting increase in atmospheric CO2 concentration. 相似文献
20.
Variations in carbon isotopic ratios ( δ
13C) of C 3 plants and distribution of C 4 plants were investigated along an altitudinal transect on the eastern slope of Mount Gongga, and the environmental effects
on them were discussed. It is shown that plants with C 4 photosynthetic pathway mainly occur at altitudes below 2100 m a.s.l., suggesting that the low summer temperature is responsible
for the distributional pattern. In addition, δ
13C of C 3 plants increases with elevation at the region above 2000 m a.s.l. with the characteristics of humid climate, and the increase
rate in δ
13C for C 3 plants is about 1.3% per kilometer. Temperature determines the altitudinal trend of δ
13C. 相似文献
|