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1.
Fluid inclusions as captured in homogeneous fluids in rocks and minerals have been extensively studied and successfully applied to exploring the metalloge- netic temperature and pressure of metallic ore deposits and in investigating hydrocarbon generation, migra- tion, etc.[1―6]. In regard to multiple forms of immis- cible inclusions in rocks and minerals, a significant amount of research has already been conducted toward the immiscible inclusions and “boiling” inclusions in CO2-H2O system…  相似文献   

2.
Minerals formed during magma crystallization trap droplets of melt that are preserved as primary or secondary inclusions. Depending on the rate of cooling, the droplets may solidify as glass, or crystallize. Inclusions may contain one or more bubbles, or none. When inclusions are heated the glass or crystalline material are melted and the inclusion expands, the size of bubbles diminishes, and homogenization of the inclusion occurs. It is possible to observe these transformations by means of high-temperature cameras which permit visual observations to 1600°C and above. The possibility of using the homogenization of inclusions to determine the temperature of formation of the host mineral has been demonstrated experimentally, using inclusions in artificial diopside formed at 1300 ± 10°. Melt inclusions in phenocrysts from nepheline basalt, fergusite porphyry, and tephrite were investigated. In the leucite-bearing rocks leucite crystallized at 1600° or above, and clinopyroxene in the range 1380–1250°. The central part of olivines in nepheline basalt formed at 1290–1270° and the peripheral zones at 1160–1120°; nepheline formed at 1290–1250°; the central part of pyroxenes at 1280–1250° and the peripheral zones at 1160–1120°. These temperatures suggest almost dry magma. Gas from the bubbles of individual inclusions has been analyzed. The predominant gaseous component of the early crystallization stage of the nepheline basalt and fergusite porphry was CO2, H2S, SO2, NH., HCl, HF, and H. comprise less than 5 volume percent except in olivine of olivine basalt in which the total content of these gases was on average 6.22 volume percent, and in leucite of fergusite porphyry in which H2 was on average 12.7 volume percent. The main gas component in the crystallization of the leucite tephrite were nitrogen and rare gases. Liquid hydrocarbons in the secondary inclusions in pyroxene from nepheline basalt can be accounted for by their assimilation by the magma from enclosing rocks during its rise.  相似文献   

3.
The northeastern area of Sichuan Basin, southwestern China, is the area with the maximal reserve of natural gas containing higher hydrogen sulphide (H2S) that has been found among the petroliferous basins of China, with the proven and controlled gas reserve of more than 200 billion cubic meters. These gas pools, with higher H2S contents averaging 9%, some 17%, are mainly distributed on structural belts of Dukouhe, Tieshanpo, Luojiazhai, Puguang, etc., while the oolitic-shoal dolomite of the Triassic Feixianguan Fm. (T1f) is the reservoir. Although many scholars regard the plentiful accumulation of H2S within the deep carbonate reservoir as the result of Thermochemical Sulfate Reduction (TSR), however, the process of TSR as well as its residual geological and geochemical evidence is still not quite clear. Based on the carbon isotopic analysis of carbonate strata and secondary calcite, etc., together with the analysis of sulfur isotopes within H2S, sulphur, gypsum, iron pyrites, etc., as well as other aspects including the natural gas composition, carbon isotopes of hydrocarbons reservoir petrology, etc., it has been proved that the above natural gas is a product of TSR. The H2S, sulphur and calcite result from the participation of TSR reactions by hydrocarbon gas. During the process for hydrocarbons being consumed due to TSR, the carbons within the hydrocarbon gas participate in the reactions and finally are transferred into the secondary calcite, and become the carbon source of secondary calcite, consequently causing the carbon isotopes of the secondary calcite to be lower (−18.2‰). As for both the intermediate product of TSR, i.e. sulfur, and its final products, i.e. H2S and iron pyrites, their sulfur elements are all sourced from the sulfate within the Feixianguan Fm. During the fractional processes of sulfur isotopes, the bond energy leads to the 32S being released firstly, and the earlier it is released, the lower δ 34S values for the generated sulphide (H2S) or sulfur will be. However, for the anhydrite that participates in reactions, the higher the reaction degree, the more 32S is released, while the less 32S remains and the more δ 34S is increased. The testing results have proved the process of the dynamic fractionation of sulfur isotopes.  相似文献   

4.
Kusakabe  M.  Mizutani  Y.  Kometani  M. 《Bulletin of Volcanology》1982,45(3):203-209

Sulphur isotopic compositions of pyrite, anhydrite and native sulphur in volcanic ashes discharged by the 1979 eruption of Ontake volcano, Nagano, Japan were determined. The isotopic data indicate that sulphate in anhydrite and a part of native sulphur were produced by the disproportionation reaction of sulphite formed by dissolution of SO2 in volcanic gases into water which filled a mud reservoir probably located just below the crater zone. Some part of H2S in volcanic gases was fixed as pyrite and some was oxidised to form native sulphur. Hydrothermal alteration of country rocks to form pyrite, anhydrite and clay minerals had proceeded in the mud reservoir before eruption at temperatures ranging from 110° to 185°C which were estimated by oxygen isotopic fractionation between anhydrite and water.

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5.
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   

6.
Lastarria volcano (25°10′ S, 68°31′ W; 5,697 m above sea level), located in the Central Andes Volcanic Zone (northern Chile), is characterized by four distinct fumarolic fields with outlet temperatures ranging between 80°C and 408°C as measured between May 2006–March 2008 and April–June 2009. Fumarolic gasses contain significant concentrations of high temperature gas compounds (i.e., SO2, HCl, HF, H2, and CO), and isotopic ratios (3He/4He, δ13C–CO2, δ18O–H2O, and δD–H2O) diagnostic of magmatic gas sources. Gas equilibria systematics, in both the H2O-H2-CO2-CO-CH4 and alkane–alkene C3 system, suggest that Lastarria fumarolic gasses emanate from a superheated vapor that is later cooled and condensed at relatively shallow depths. This two-stage process inhibits the formation of a continuous aquifer (e.g., horizontal liquid layer) at relatively shallow depth. Recent developments in the magmatic gas system may have enhanced the transfer and release of heat causing shallow aquifer vaporization. The consequent pressure increase and aquifer vaporization likely triggered the inflation events beginning in 2003 at the Lastarria volcano.  相似文献   

7.
Methods used previously to remove compositional modifications from volcanic gas analyses for Mount Etna and Erta'Ale lava lake have bean employed to estimate the gas phase composition at Nyiragongo lava lake, based on samples obtained in 1959. H2O data were not reported in 11 of the 13 original analyses. The restoration methods have been used to estimate the H2O contents of the samples and to correct the analyses for atmospheric contamination, loss of sulfur and for pre- and pest-collection oxidation of H2S, S2, and H2. The estimated gas compositions are relatively CO2-rich, low in total sulfur and reduced. They contain approximately 35–50% CO2 45–55% H2O, 1–2% SO2, 1–2% H2., 2–3% CO, 1.5–2.5% H2S, 0.5% S2 and 0.1% COS over,he collection temperature range 102° to 960° C. The oxygen fugacities of the gases are consistently about half an order of magnitude below quartz-magnetite-fayalite. The low total sulfur content and resulting low atomic S/C of the Nyiragongo gases appear to be related to the relatively low fO2 of the crystallizing lava. At temperatures above 800°C and pressures of 1–1.5 k bar, the Nyiragongo gas compositions resemble those observed in primary fluid inclusions believed to have formed at similar temperatures and pressures in nephelines of intrusive alkaline rocks. Cooling to 300°C, with fO2 buffered by the rock, results in gas compositions very rich in CH4 (50–70%) and resembling secondary fluid inclusions formed at 200–500°C in alkaline rocks. Below 600°C the gases become supersaturated in carbon as graphite. These inferences are corroborated by several reports of hydrocarbons in plutonic alkaline rocks, and by the presence of CH4-rich waters in Lake Kivu — a lake on the flanks of Nyiragongo volcano.  相似文献   

8.
2 and approximately 85% SO2 of the total sulfur gas. Relative amounts of He, Ar, and N2 show a distinct hot-spot signature ( ). The δ13C–CO2 is approximately −3.6‰ and δ34ST is approximately +3.3‰. The δD/δ18O of fumarole H2O 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 m3/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.% CO2, and sulfur gas is dominated by H2S. Relative amounts of He, Ar, and N2 show extensive mixing between hot spot and air or air-saturated meteoric water components but the average . The δ13C–CO2 is approximately −3.5‰ and δ34ST is approximately −0.8‰. The δD/δ18O 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   

9.
The mechanics of explosive eruptions influence magma ascent pathways. Vulcanian explosions involve a stop–start mechanism that recurs on various timescales, evacuating the uppermost portions of the conduit. During the repose time between explosions, magma rises from depth and refills the conduit and stalls until the overpressure is sufficient to generate another explosion. We have analyzed major elements, Cl, S, H2O, and CO2 in plagioclase-hosted melt inclusions, sampled from pumice erupted during four vulcanian events at Soufrière Hills volcano, Montserrat, to determine melt compositions prior to eruption. Using Fourier transform infrared spectroscopy, we measured values up to 6.7 wt.% H2O and 80 ppm CO2. Of 42 melt inclusions, 81 % cluster between 2.8 and 5.4 wt.% H2O (57 to 173 MPa or 2–7 km), suggesting lower conduit to upper magma reservoir conditions. We propose two models to explain the magmatic conditions prior to eruption. In Model 1, melt inclusions were trapped during crystal growth in magma that was stalled in the lower conduit to upper magma reservoir, and during trapping, the magma was undergoing closed-system degassing with up to 1 wt.% free vapor. This model can explain the melt inclusions with higher H2O contents since these have sampled the upper parts of the magma reservoir. However, the model cannot explain the melt inclusions with lower H2O because the timescale for plagioclase crystallization and melt inclusion entrapment is longer than the magma residence time in the conduit. In Model 2, melt inclusions were originally trapped at deeper levels of the magma chamber, but then lost hydrogen by diffusion through the plagioclase host during periodic stalling of the magma in the lower conduit system. In this second scenario, which we favor, the melt inclusions record re-equilibration depths within the lower conduit to upper magma reservoir.  相似文献   

10.
Studies of the sulphur hydrolysis reaction, 4S + 4H2O /ag 3H2S + HSO4? + H+, were conducted between 200 and 320°C in sealed silica glass tubes. The isotope exchange reaction: H218O + HS16O4? /ag H216O + HS18O4? is so rapid at the low pH (1.5–3) as to be unquenchable. However, the sulphur isotope exchange reaction: H234S+ H32SO4? /ag H232S + H34SO4? gave t12 values of 0.1, 0.3 and 1.7 days at 320, 260 and 200°C respectively and equilibrium H2S - HSO4? sulphur isotope fractionation values of 20.9, 22.4, 24.8, 26.7 and 29.3‰ at 320, 290, 260, 230 and 200°C respectively. This latter data is represented by: 1000lnα(HSO4??H2S) = 5.07 (106T?2) + 6.33, and has valuable applications in geothermal and ore deposit studies.  相似文献   

11.
Gases trapped in lavas of three main flows of the Ardoukôba eruption (8 to 15 November, 1978) have been analysed by mass spectrometry. These analyses concern both plagioclase phenocrysts and microcrystalline mesostasis. Fluids are released between 500°C and 1200°C, and consist of H2O, CO2, CO, N2, SO2, HCl, H2, CH4 with traces of hydrocarbons and H2S. The total content is less than 0.3–0.4 wt. % of samples with about 0.1–0.15 wt % of H2O. No significant variation among the three flows is observed. Plagioclase phenocrysts are less abundant in fluids than the mesostasis (～2/3). The gases trapped in these phenocrysts are richer in CO and organic compounds, whereas mesostasis contain more H2O, CO2 and SO2. CO is likely produced by reduction of CO2 and H2O with carbon during either analyses or eruption itself, or is of primary origin. In the latter case, gas composition suggests an entrapment temperature of about 1200°C ± 75°C. Kinetic study of the water and carbon dioxide release allows to calculate the diffusion characteristics of these fluids. Water and carbon dioxide behave rather similarly. Plagioclase gives a single activation energy value (8 Kcal/mole), while mesostasis gives two values (8 Kcal/mole, 15 Kcal/mole). Diffusion coefficients at 20°C are estimated to fall in the range 10?13 · 10?12 cm2 · sec?1.  相似文献   

12.
The chemical and isotopic compositions (δDH2O, δ18OH2O, δ18OCO2, δ13CCO2, δ34S, and He/N2 and He/Ar ratios) of fumarolic gases from Nisyros, Greece, indicate that both arc-type magmatic water and local seawater feed the hydrothermal system. Isotopic composition of the deep fluid is estimated to be +4.9±0.5‰ for δ18O and ?11±5‰ for δD corresponding to a magmatic water fraction of 0.7. Interpretation of the stable water isotopes was based on liquid–vapor separation conditions obtained through gas geothermometry. The H2–Ar, H2–N2, and H2–H2O geothermometers suggest reservoir temperatures of 345±15 °C, in agreement with temperatures measured in deep geothermal wells, whereas a vapor/liquid separation temperature of 260±30 °C is indicated by gas equilibria in the H2O–H2–CO2–CO–CH4 system. The largest magmatic inputs seem to occur below the Stephanos–Polybotes Micros crater, whereas the marginal fumarolic areas of Phlegeton–Polybotes Megalos craters receive a smaller contribution of magmatic gases.  相似文献   

13.
Abundant fluid inclusions in olivine of dunite xenoliths (～1–3 cm) in basalt dredged from the young Loihi Seamount, 30 km southeast of Hawaii, are evidence for three coexisting immiscible fluid phases—silicate melt (now glass), sulfide melt (now solid), and dense supercritical CO2 (now liquid + gas)—during growth and later fracturing of some of these olivine crystals. Some olivine xenocrysts, probably from disaggregation of xenoliths, contain similar inclusions.Most of the inclusions (2–10 μm) are on secondary planes, trapped during healing of fractures after the original crystal growth. Some such planes end abruptly within single crystals and are termed pseudosecondary, because they formed during the growth of the host olivine crystals. The “vapor” bubble in a few large (20–60 μm), isolated, and hence primary, silicate melt inclusions is too large to be the result of simple differential shrinkage. Under correct viewing conditions, these bubbles are seen to consist of CO2 liquid and gas, with an aggregate ? = ～ 0.5–0.75 g cm?3, and represent trapped globules of dense supercritical CO2 (i.e., incipient “vesiculation” at depth). Some spinel crystals enclosed within olivine have attached CO2 blebs. Spherical sulfide blebs having widely variable volume ratios to CO2 and silicate glass are found in both primary and pseudosecondary inclusions, demonstrating that an immiscible sulfide melt was also present.Assuming olivine growth at ～ 1200°C and hydrostatic pressure from a liquid lava column, extrapolation of CO2P-V-T data indicates that the primary inclusions were trapped at ～ 220–470 MPa (2200–4700 bars), or ～ 8–17 km depth in basalt magma of ? = 2.7 g cm?3. Because the temperature cannot change much during the rise to eruption, the range of CO2 densities reveals the change in pressure from that during original olivine growth to later deformation and rise to eruption on the sea floor. The presence of numerous decrepitated inclusions indicates that the inclusion sample studied is biased by the loss of higher-density inclusions and suggests that some part of these olivine xenoliths formed at greater depths.  相似文献   

14.
Equilibria calculations of high-temperature volcanic gases from lava lakes are carried out on the basis of best volcanic gas samples. The equilibrium gas composition at temperatures from 800° to 1400°K and pressures up to 25 kilobars (in ideal gas system) was calculated using the free energy minimization model as well as the Newton-Raphson methods. It is shown that the juvenile «magmatic gas » of basaltic magma consists of three components: H2O, SO2, CO2; the water vapor being about 60%. The increase of temperature under constant pressure results in the increase of the SO2 concentration and in the simultaneous decrease of H2S. Under the same conditions the ratios CO/CO2 and H2/H2O are found to increase. Methane cannot be a component of «magmatic gas» corresponding to the elemental composition of basaltic lava gases. The calculated values of \(P_{O_2 } \) are in good agreement with the experimental data obtained from direct measurements of \(P_{O_2 } \) in lava lakes and experiments with basaltic melts.  相似文献   

15.
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 C27, C28 and C29 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 (nC14−nC20) of the saturated hydrocarbon fraction in the carbonaceous bitumen is extremely higher than the content of heavy hydrocarbons. The light/heavy hydrocarbon ratios (ΣnC21 −/ΣnC22 + 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   

16.
Phreatic eruptions occurred at the Meakandake volcano in 1988, 1996, 1998, 2006, and 2008. We conducted geochemical surveillance that included measurements of temperature, SO2 emission rates, and volcanic gas composition from 2003 to 2008 at the Nakamachineshiri (NM), Northwest (NW), and Akanuma (AK) fumarolic areas, and the 96–1 vent, where historical eruptions had occurred. The elemental compositions of the gases discharged from the different areas are similar compared with the large variations observed in volcanic gases discharged from subduction zones. All the gases showed high apparent equilibrium temperatures, suggesting that all these gases originated from a common magmatic gas. The gases discharged from each area also exhibited different characteristics, which are probably the results of differences in the conditions of meteoric water mixing, quenching of chemical reactions, and vapor-liquid separation. The highest apparent equilibrium temperatures (about 500°C) were observed in the case of NW fumarolic gases, despite the low outlet temperature of about 100°C at these fumaroles. Since the NW fumaroles were formed as a result of the 2006 phreatic eruption, the high-temperature gas supply to the NW fumarole suggests that the phreatic eruption was caused by the ascent of high-temperature magmatic gases. The temperatures, compositions, and emission rates of the NM and 96–1 gases did not show any appreciable change after the 2006 eruption, indicating that each fumarolic system had a separate magmatic-hydrothermal system. The temperatures, compositions, and emission rates of the NM fumarolic gases were apparently constant, and these fumaroles are inferred to be formed by the evaporation of a hydrothermal system with a constant temperature of about 300°C. The 96–1 gas compositions showed large changes during continuous temperature decrease from 390° to 190°C occurred from 2003 to 2008, but the sulfur gas emission rates were almost constant at about four tons/day. At the 96–1 vent, the SO2/H2S ratio decreased, while the H2/H2O ratio remained almost constant; this was probably caused by the rock-buffer controlled chemical reaction during the temperature decrease.  相似文献   

17.
The kinetic parameters of generation have been obtained for different hydrocarbon classes, including methane, C2-C5 gas hydrocarbons, C6-C13 light hydrocarbons and C13+ heavy hydrocarbons, and vitrinite reflectance (R°) by the kinetic simulating experiment of kerogen cracking. Then, combined with the detailed geology of Sichuan Basin, the effective gas-generating intensity of the Lower Cambrian source rock is approximately estimated by applying these parameters.  相似文献   

18.
To investigate the relationship between volatile abundances and eruption style, we have analyzed major element and volatile (H2O, CO2, S) concentrations in olivine-hosted melt inclusions in tephra from the 2000 yr BP eruption of Xitle volcano in the central Trans-Mexican Volcanic Belt. The Xitle eruption was dominantly effusive, with fluid lava flows accounting for 95% of the total dense rock erupted material (1.1 km3). However, in addition to the initial, Strombolian, cinder cone-building phase, there was a later explosive phase that interrupted effusive activity and deposited three widespread ash fall layers. Major element compositions of olivine-hosted melt inclusions from these ash layers range from 52 to 58 wt.% SiO2, and olivine host compositions are Fo84–86. Water concentrations in the melt inclusions are variable (0.2–1.3 wt.% H2O), with an average of 0.45±0.3 (1σ) wt.% H2O. Sulfur concentrations vary from below detection (50 ppm) to 1000 ppm but are mostly ≤200 ppm and show little correlation with H2O. Only the two inclusions with the highest H2O have detectable CO2 (310–340 ppm), indicating inclusion entrapment at higher pressures (700–900 bars) than for the other inclusions (≤80 bars). The low and variable H2O and S contents of melt inclusions combined with the absence of less soluble CO2 indicates shallow-level degassing before olivine crystallization and melt inclusion formation. Olivine morphologies are consistent with the interpretation that most crystallization occurred rapidly during near-surface H2O loss. During cinder cone eruptions, the switch from initial explosive activity to effusive eruption probably occurs when the ascent velocity of magma becomes slow enough to allow near-complete degassing of magma at shallow depths within the cone as a result of buoyantly rising gas bubbles. This allows degassed lavas to flow laterally and exit near the base of the cone while gas escapes through bubbly magma in the uppermost part of the conduit just below the crater. The major element compositions of melt inclusions at Xitle show that the short-lived phase of renewed explosive activity was triggered by a magma recharge event, which could have increased overpressure in the storage reservoir beneath Xitle, leading to increased ascent velocities and decreased time available for degassing during ascent.  相似文献   

19.
Two kinds of inclusions, fluid-melting inclusion and gas-liquid inclusion, are present in the Huanggangliang deposit in eastern Inner Mongolia. Temperature ranges from 1050°C of fluid-melting inclusion to 150°C of liquid inclusion. Away from intrusion, the inclusions of orebodies intend to be characterized by simpler type, lower temperature and lower salinity, as well as weakened relation to intrusion. The metallization of the Huanggangliang deposit is characterized by multiple activities of ore-forming fluid, multi-source, multi-stage accumulation of ore-forming material, F-rich environment, enrichment of F, organic gas, CO2 and N2, and involving of residual magma.  相似文献   

20.
A field gas chromatograph, built in 1978, was used in the field to directly analyse volcanic gases before water vapor condensation. Tested in Vulcano (Italy), Kilauea (Hawaii) and Merapi (Indonesia), this field measurement technique provides the actual composition of the volcanic gas mixture. The technique avoids the depletion of sulfur gases and the dissolution of the acid gases in the condensed water during the cooling. Thus the mixture of H2S and SO2 in fumarolic and high temperature gases (up to 819°C) in equilibrium at the emission temperature was examined.  相似文献   

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