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1.
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
2.
Significant changes in the helium and carbon isotopic composition of shallow thermal waters vs. gas and a crater fumarolic gas have been recorded at Stromboli prior and during the 2002–2003 eruption. The 3He/ 4He ratios corrected for air contamination (Rc/Ra), and δ 13C of fumarolic gases gradually increased from May to November 2002 before the eruption onset. These variations imply early degassing of a gas-rich magma at depth that likely fed both the intense Strombolian activity and small lava overflows recorded during that period. The lava effusion of late December 2002 was shortly preceded by a marked Rc/Ra decrease both in water and fumarolic gases. Comparison of He/CO 2 and CH 4/CO 2 ratios in dissolved gas and with values rules out the Rc/Ra decrease due to an increasing input of radiogenic 4He. The Rc/Ra decrease is attributed to the He isotope fractionation during rapid magma ascent and degassing. A new uprising of 3He-rich magma probably occurred in January to February 2003, when Rc/Ra ratios displayed the highest values in dissolved gases ever measured before (4.56 Rc/Ra). The increase in He/CO 2 and CH 4/CO 2 ratios and decrease in δ 13C of dissolved CO 2 was recorded after the 5 April 2003 explosive paroxysm, likely caused by enhanced gas-water interaction inducing CO 2 dissolution. No anomalous Rc/Ra values were recorded in the same period, when usual Strombolian activity gradually resumed.Editorial responsibility: H Shinohara 相似文献
3.
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
4.
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
6.
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
7.
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
8.
A semiempirical mathematical model of iron and manganese migration from bottom sediments into the water mass of water bodies has been proposed based on some basic regularities in the geochemistry of those elements. The entry of dissolved forms of iron and manganese under aeration conditions is assumed negligible. When dissolved-oxygen concentration is <0.5 mg/L, the elements start releasing from bottom sediments, their release rate reaching its maximum under anoxic conditions. The fluxes of dissolved iron and manganese (Me) from bottom sediments into the water mass ( J Me) are governed by the gradients of their concentrations in diffusion water sublayer adjacent to sediment surface and having an average thickness of h = 0.025 cm: \({J_{Me}} = - {D_{Me}}\frac{{{C_{Me\left( {ss} \right)}} - {C_{Me\left( w \right)}}}}{h}\) ( D Me ≈ 1 × 10 –9 m 2/s is molecular diffusion coefficient of component Me in solution; C Me(ss) and C Me(w) ≈ 0 are Me concentrations on sediment surface, i.e., on the bottom boundary of the diffusion water sublayer, and in the water mass, i.e., on the upper boundary of the diffusion water sublayer). The value of depends on water saturation with dissolved oxygen ( \({\eta _{{O_2}}}\)) in accordance with the empiric relationship \({C_{Me\left( {ss} \right)}} = \frac{{C_{_{Me\left( {ss} \right)}}^{\max }}}{{1 + k{\eta _{{O_2}}}}}\) ( k is a constant factor equal to 300 for iron and 100 for manganese; C Me(ss) max is the maximal concentration of Me on the bottom boundary of the diffusion water sublayer with C Fe(ss) max ≈ 200 μM (11 mg/L), and C Mn(ss) max ≈ 100 μM (5.5 mg/L). 相似文献
9.
Natural gases discovered up to now in Lishui Sag, the East China Sea Basin, differ greatly in gaseous compositions, of which hydrocarbon gases amount to 2%–94% while non-hydrocarbon gases are dominated by CO 2. Their hydrocarbon gases, without exception, contain less than 90% of methane and over 10% of C 2 + heavier hydrocarbons, indicating a wet gas. Carbon isotopic analyses on these hydrocarbon gases showed that δ 13C 1, δ 13C 2 and δ 13C 3 are basically lighter than ?44‰, ?29‰ and ?26‰, respectively. The difference in carbon isotopic values between methane and ethane is great, suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation. δ 13 \(C_{CO_2 } \) values of nonhydrocarbon gases are all heavier than ?10‰, indicating a typical abiogenic gas. The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit, consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter. Moreover, δ 13C 1 values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰ heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit while δ 13C 2 and δ 13C 3 values of the former are over 9‰ heavier than those of the latter. Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag, where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter, therefore, natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks. 相似文献
10.
The Tieluping silver deposit, located in the NE-trending faults within the metamorphic basement of the Xiong'er Mountain, is a typical altered fracture type deposit. Its ore-forming process includes three stages with temperatures concentrated at 373°C, 223°C and 165°C respectively. With δD=90‰, \(\delta ^{13} C_{CO_2 } \)=2.0‰ and δ{si18}O=8094‰, the early stage fluid was generated from reworking and metamorphism of the carbonate rich formation; the late one, with δD=?70‰, \(\delta ^{13} C_{CO_2 } \)=-1.2‰, δ 18O=1.89‰, was meteoric hydrothermal solution; and the middle. δD=?109‰, \(\delta ^{13} C_{CO_2 } \)=0.1‰, δ 18O=1.79‰, might be a hybrid mixed by reworking-metamorphic fluid and meteoric hydrothermal solution. Crystallized rapidly in the condition of fluid-boiling and fluid-mixing, the middle stage minerals have far more fluid inclusions with higher content of ions, higher ratios of H 2O/CO 2 and KN/MC. Consequently, they have much more ore elements such as gold compared with those of the early and late stages. It was the northward intracontinental subduction along the Machaoying fault during the Mesozoic collision between the South China and North China paleocontinents that intrigued large-scale fluidization and magmatism and led to the appearance of more than 10 large and medium hydrothermal deposits, including the Tieluping silver deposit. The study on ore-forming fluidization of the Tieluping silver deposit proves the CPMF model. 相似文献
11.
The Tieluping silver deposit, located in the NE-trending faults within the metamorphic basement of the Xiong'er Mountain, is a typical altered fracture type deposit. Its ore-forming process includes three stages with temperatures concentrated at 373°C, 223°C and 165°C respectively. With δD=90‰,\(\delta ^{13} C_{CO_2 } \)=2.0‰ and δ{si18}O=8094‰, the early stage fluid was generated from reworking and metamorphism of the carbonate rich formation; the late one, with δD=−70‰,\(\delta ^{13} C_{CO_2 } \)=-1.2‰, δ18O=1.89‰, was meteoric hydrothermal solution; and the middle. δD=−109‰,\(\delta ^{13} C_{CO_2 } \)=0.1‰, δ18O=1.79‰, might be a hybrid mixed by reworking-metamorphic fluid and meteoric hydrothermal solution. Crystallized rapidly in the condition of fluid-boiling and fluid-mixing, the middle stage minerals have far more fluid inclusions with higher content of ions, higher ratios of H2O/CO2 and KN/MC. Consequently, they have much more ore elements such as gold compared with those of the early and late stages. It was the northward intracontinental subduction along the Machaoying fault during the Mesozoic collision between the South China and North China paleocontinents that intrigued large-scale fluidization and magmatism and led to the appearance of more than 10 large and medium hydrothermal deposits, including the Tieluping silver deposit. The study on ore-forming fluidization of the Tieluping silver deposit proves the CPMF model. 相似文献
12.
Natural gases discovered up to now in Lishui Sag, the East China Sea Basin, differ greatly in gaseous compositions, of which hydrocarbon gases amount to 2%–94% while non-hydrocarbon gases are dominated by CO2. Their hydrocarbon gases, without exception, contain less than 90% of methane and over 10% of C2
+ heavier hydrocarbons, indicating a wet gas. Carbon isotopic analyses on these hydrocarbon gases showed that δ
13C1, δ
13C2 and δ
13C3 are basically lighter than −44‰, −29‰ and −26‰, respectively. The difference in carbon isotopic values between methane and ethane is great, suggesting a biogenic oil-type gas produced by the mixed organic matter at peak generation. δ
13
\( C_{CO_2 } \)
values of nonhydrocarbon gases are all heavier than −10‰, indicating a typical abiogenic gas. The simulation experiment on hydrocarbon generation of organic matter in a closed gold-tube system showed that the proportion of methane in natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit is obviously higher than that in natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit, consequently the proportion of heavier hydrocarbons of the former is remarkably lower than that of the latter. Moreover, δ
13C1 values of natural gases produced by terrigenous organic matter in the Lingfeng Formation marine deposit are about 5‰ heavier than those of natural gases derived from the aquatic and terrigenous mixed organic matter in the Yueguifeng Formation lacustrine deposit while δ
13C2 and δ
13C3 values of the former are over 9‰ heavier than those of the latter. Currently the LS36-1 oil-gas pool is the only commercial oil-gas reservoir in Lishui Sag, where carbon isotopic compositions of various hydrocarbon components differ greatly from those of natural gases produced by the Lingfeng Formation organic matter but are very similar to those of natural gases derived from the Yueguifeng Formation organic matter, therefore, natural gases in the LS36-1 oil-gas pool are mainly derived from the Yueguifeng Formation lacustrine source rock rather than the Lingfeng Formation marine or Mingyuefeng Formation coal-measures source rocks. 相似文献
13.
Let { Y, Y
i
, −∞ < i < ∞} be a doubly infinite sequence of identically distributed and asymptotically linear negative quadrant dependence random
variables, { a
i
, −∞ < i < ∞} an absolutely summable sequence of real numbers. We are inspired by Wang et al. (Econometric Theory 18:119–139, 2002) and Salvadori (Stoch Environ Res Risk Assess 17:116–140, 2003). And Salvadori (Stoch Environ Res Risk Assess 17:116–140, 2003) have obtained Linear combinations of order statistics to estimate the quantiles of generalized pareto and extreme values
distributions. In this paper, we prove the complete convergence of under some suitable conditions. The results obtained improve and generalize the results of Li et al. ( 1992) and Zhang ( 1996). The results obtained extend those for negative associated sequences and ρ *-mixing sequences.
CIC Number O211, AMS (2000) Subject Classification 60F15, 60G50
Research supported by National Natural Science Foundation of China 相似文献
14.
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
15.
Summary If the condition R( A)=k(n), where A is the design matrix of the type n × k and k the number of parameters to be determined, is not satisfied, or if the covariance matrix H is singular, it is possible to determine the adjusted value of the unbiased estimable function of the parameters f(), its dispersion D(
(x)) and
2
as the unbiased estimate of the value of
2
by means of an arbitrary g-inversion of the matrix
. The matrix
, because of its remarkable properties, is called the Pandora Box matrix. The paper gives the proofs of these properties and the manner in which they can be employed in the calculus of observations. 相似文献
16.
Dajing Cu-Sn-Ag-Pb-Zn ore deposit, in the Inner Mongolia Autonomous Region of China, is a fissure-filling hydrothermal ore
deposit. The δ D values of quartz-hosted inclusion water are centered at −100%.– −130%.. The δ 34S values of sulfide ore minerals and δ 13
C values of carbonate gangue minerals vary from −0.3%. to 2.6%. and from −2.9%. to −7.0%., respectively. Integrated isotopic
data point to two major contributions to the mineralizing fluid that include a dominant meteoric-derived groundwater, and
sulfur and carbon species from hypogene magma. Linear trends are exhibited on the gaseous H 2O versus CO 2 plot, and plots of CO, N 2, CH 4, and C 2H 6. It is shown by quantitative simulation that magma degassing cannot explain the linear trends. Hence, these linear trends
are interpreted in terms of mixing of CO 2-rich magmatic fluid with meteoric-derived groundwater. The groundwater circulated in Paleozoic sedimentary rocks and absorbed
CO, N 2, CH 4, C 2H 6 and radiogenic Ar from organic matter. Cooling effects resulting from mixing have caused the precipitation of ore minerals. 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.
Palaeodietary analysis is one of important topics in bioarchaeology field and has been paid great at- tention to by Chinese archaeometrists recently. Ancient human bones in Jiahu Site were analyzed by means of stable isotopes of C, N and O. 13 human bones were excluded from 28 bones for dietary re- construction due to their unusual collagen contents, C and N contents, and C/N atomic ratios espe- cially. δ 13C (-20.37±0.53‰) in collagen of remaining samples showed that C3 food were consumed mainly, which is consistent of the archaeological findings that rice was the staple in Jiahu. According to the difference of δ 15N and δ 13C values in bone collagen, the samples can be classified into four clusters. The changes of δ 15N values in bone collagen and δ 13C values in hydroxylapatite through whole cultural phases indicated the transition from hunting to gathering and fishing to rice agriculture and animal domestication ultimately. Meanwhile, the δ 18O change in hydroxylapatite showed that pa- laeoclimate was relatively constant during Jiahu culture. 相似文献
20.
A simple law of wear rate is examined for the process of gouge generation during the frictional sliding of simulated faults in rocks, by use of the Pi theorem method (dimensional analysis) and existing experimental data. The relationship between wear rate ( t/d) and the applied stress can be expressed by the power-law relations $$\frac{t}{d} = C_\sigma \sigma ^{m\sigma } ,\frac{t}{d} = C_\tau \tau ^{m\tau }$$ where t is the thickness of the gouge generated on the frictional surfaces, d is the fault displacement, σ and τ are normal stress and shear stress, respectively, and C σ, C τ, m σ and m τ are constants. These results indicate that the exponent coefficients m σ and m τ and the coefficients C σ and C τ depend on the material hardness of the frictional surfaces. By using the wear rates of natural faults, these power-law relationships may prove to be an acceptable palaeopiezometer of natural faults and the lithosphere. 相似文献
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