Abstract During the ongoing uplift and expansion of the southeastern margin of the Tibetan Plateau, the front edge of the Sichuan‐Yunnan rhombic block (SYB) has experienced intense tectonic activity and frequent seismicity. In this study, the fluid geochemistry in the primary active faults at the front edge of the SYB was investigated, with the aim of understanding the tectonic activity and intersection relationship between the Xiaojiang fault (XJF) and the Red River fault (RRF). Thermal spring water and gases exhibit a coupled spatial distribution relationship; relatively high ion concentrations and 3He/4He ratios (Rc/Ra ratios of 0.21 to 0.62Ra) are observed along the RRF, Qujiang fault (QJF), and Shiping‐Jianshui fault (SJF). Multidisciplinary research results have indicated that mantle‐derived intrusion has been detected in the crust beneath the QJF and SJF. The current tectonic activity in the front edge of the SYB remains intense, with compressive stresses shifting toward the western side of the XJF and accumulating on the QJF and SJF. This has led to the development of fractures, enhancing the water–rock interaction and deep‐derived gas degassing along the faults. The unmixing characteristics of fluids at the intersection area of these two faults suggest the absence of conduits for fluid migration between the faults. Owing to the lower gas 3He/4He ratios, lower shear strain rates, stable reservoir temperature field, and extremely low historical seismicity in the Indo‐Chinese block, it is speculated that the current movement of the XJF may not cut through the RRF and continue southward.

The Three Rivers Lateral Collision Zone (TRLCZ), situated at the southeastern margin of the Tibetan Plateau, is a crucial frontier where materials from the plateau flow southeastward. This study extensively investigated the hydrochemical characteristics and origin of helium and carbon isotopes in 73 thermal springs within the TRLCZ. The analysis revealed dominant processes, including carbonate and silicate interactions, resulting in elevated concentrations of HCO3− and Na+. The impact of Ca/Mg-rich minerals, particularly dolomite, influenced the cation composition. Additionally, gypsum dissolution, notably in the Lancangjiang Fault and Weixi–Qiaohou Fault, was highlighted through Ca/SO4 ratios. The positive correlation between SO42− and Cl− indicated dilution by shallow cold water, explaining the lower SO42− content in the Jingshajiang–Zhongdian Fault and Nujiang Fault compared to the Weixi–Qiaohou Fault and Lancangjiang Fault. The circulation depth of thermal spring water varied, with the northern Weixi–Qiaohou Fault exhibiting the shallowest circulation depth (~3 km), while the Jingshajiang–Zhongdian Fault and southern segments of the Nujiang Fault displayed deeper depths—ranging from 4 to 7 km. A positive correlation between the circulation depth and fault activity was also observed. The Rc/Ra ratios of free gas samples, predominantly indicating crustal origin, varied from 0.01 Ra to 0.53 Ra. Elevated Rc/Ra ratios in the research area suggested potential minor additions of mantle helium through faults and fractures. Crustal limestone was identified as the primary source of CO2-rich samples, with δ13CCO2 values ranging from −1.6‰ to −7.2‰, while trace amounts of mantle CO2 were found. The spatial distribution of the H2 concentration, CO2 concentration, He concentration, and mantle He proportions in gases indicated that higher values of He concentration and mantle He% always occur near sampling points with deeper circulation depths. However, no similar correlation was observed for H2 and CO2. Most earthquakes of magnitude 5 or greater occurred near the regions with high values of mantle source He release, highlighting the critical role of mantle fluids in the occurrence of earthquakes in the region. In this study, a fluid circulation model was developed to describe the process of fluid (water and gas) circulation migration and earthquake generation in the TRLCZ.

Based on the high-resolution remote sensing interpretation and a detailed field geological and geomorphological survey, we excavate a trench in the linear fault trough beside the Gongka Lake to reveal the direct evidence of the Holocene activity and paleo-earthquake.The trench, which is perpendicular to the fault trace, obviously manifests positive dip-slip faults and shows that the Deqin-Zhongdian Fault has dislocated the Holocene stratum.Through paleoseismic analysis of the relationship between the fault and stratigraphic ages, cracks and colluvial, and the age of sedimentation determined by means of AMS- 14 C dating, two palaeo-seismic events are identified.They are respectively between（1 140±30）-（ 1 010±30）a BP and（570±30）-（410±30）a BP.The segment in the northwest of the Deqin-Zhongdian Fault was an active fault in Holocene and was characterized as positive dip-slip.

根据2022年云南宁蒗MS 5.5地震现场调查情况,详细描述本次地震的烈度分布情况和房屋震害特征,计算各烈度区内各类房屋结构的平均震害指数和破坏比,与2012年宁蒗—盐源MS 5.7地震和历史地震震害统计规律进行对比,结果表明:①本次地震最大烈度为Ⅶ度,长轴呈NW向,与地震构造背景、震源机制解、余震序列分布和震例统计规律等科技支撑成果吻合较好;②本次地震中房屋震害较轻,主要得益于脱贫攻坚、农村危房改造和抗震改造等项目的实施,震区房屋结构的整体抗震性能加强.

The Simao Basin is characterized by strong tectonic activity and frequent seismicity. This study investigated the hydrochemical characteristics of 21 thermal springs in the Simao Basin from 2018 to 2020. In this study period, the 2018 Mojiang M5.9 earthquake caused several hydrochemical changes. The results indicate that the Simao Basin contained saline spring waters, HCO3−-rich spring waters, and SO42−-rich spring waters. In the study area, the water chemistry types were controlled by stratum lithology. Saline springs flowed through red beds and dissolved large amounts of halite, which is a rich source of Cl−and Na+ ions. In the hot spring waters, Ca2+ (Mg2+) and HCO3− were mainly derived from the dissolution of carbonate minerals, gypsum, and anhydrite of Triassic rocks. The higher SO42- content in the hot spring waters was caused by the pyrite present in Ailaoshan metamorphic rocks. The reservoir temperatures (121–289 °C) in the Simao Basin were estimated by the silica-enthalpy mixing model equation and the silica-enthalpy diagram. The hot springs had higher reservoir temperatures (>250 °C) and were mainly located at the edges of the basin. Metamorphic rocks exposed in the region had low permeabilities and these springs was close to nearby deep faults that provided deep heat. In most springs, the concentrations of Ca2+ and HCO3− ions increased obviously before the 2018 Mojiang M5.9 earthquake; however, the concentrations of these ions decreased after the earthquake. The hydrogeochemical variations might be attributed to the vigorous water-rock interactions and the mixing of secondary fluids. The entry of cold shallow groundwater caused changes in the reservoir temperatures of some spring samples.

The Weixi-Qiaohou fault zone (WQFZ) is located on the western edge of the Sichuan-Yunnan rhombic block. It connects the Red River fault zone (RRFZ) in the south with the Jinshajiang-Zhongdian fault zone (JZFZ) in the north. This study investigated the chemical components and isotopic compositions (He and C) of spring gas samples from the WQFZ. The 3He/4He ratios in hot and cold spring gases along the WQFZ ranged from 0.01 to 0.28 Ra. The majority of He isotopes indicate a crustal source. The δ13C values of CO2 ranged from −2.3 to −11.8‰. The CO2/3He vs δ13C relationship indicates that crustal limestone is the major contributor to the carbon inventory. The 3He/4He ratios of spring gases from the JZFZ, WQFZ, and RRFZ were compared. The WQFZ is an important part of the western boundary of the Sichuan-Yunnan rhombic block and had similar 3He/4He signatures as the JZFZ and RRFZ. The 3He/4He ratios (<1 Ra) of the three faults are mostly of crustal origin. The low 3He/4He ratios observed in the research area are associated with long-term radiogenic 4He dilution. The higher crustal thicknesses in the JZFZ and WQFZ compared with the RRFZ enhance the production of 4He and lower the 3He/4He ratios in surface gas emissions. However, some higher 3He/4He values found in the research area might be considered as the result of possible minor additions of mantle helium due to the existence of ductile shear zones in the lower crust. The WQFZ had lower 3He/4He values than the JZFZ and RRFZ, which might be attributable to lower fault permeability as a consequence of faulting activity. Furthermore, the 3He/4He ratios in the JZFZ are significantly higher than that of the WQFZ and closely related to strong earthquakes.

对漾濞6.4级地震灾区开展土木结构房屋加固情况与破坏形式调查。从云南相近震级地震破坏情况的对比、加固与未加固房屋的对比、强震动记录、与烈度衰减关系对比等方面进一步分析,认为抗震加固能减轻土木结构建筑的破坏。甚至可降低其宏观烈度1～2度,对抗震加固的防震减灾效果进行评估;就抗震加固工作及烈度评估工作提出建议。

Abstract Due to strong tectonic activity, the Simao Basin frequently experiences earthquakes with a magnitude of 6 or greater. This study investigated the hydrochemical characteristics of 21 thermal springs in the Simao Basin from 2018 to 2020 to determine how the 2018 Mojiang M5.9 earthquake caused hydrochemical changes. The results showed that the Simao Basin contained saline spring waters, HCO3−-rich spring waters, and SO42−-rich spring waters. Stratum lithology characteristics in the area exerted obvious control over the water chemistry characteristics. Saline springs flowed through red beds and dissolved large amounts of halite, which is rich with Cl−and Na+. Ca2+ (Mg2+) and HCO3− in the hot spring waters were mainly derived from the dissolution of carbonate minerals, gypsum, and anhydrite in Triassic rocks. The higher SO42− content in the hot spring waters was influenced by pyrite contained in Ailaoshan metamorphic rocks. The reservoir temperatures (121–289° C) in the Simao Basin were estimated by the silica-enthalpy mixing model equation and silica-enthalpy diagram. The hot springs with higher reservoir temperatures (> 250° C) were mainly located at the edges of the basin, which may correlate with nearby deep faults that provided deep heat and metamorphic rocks with low permeabilities. The concentrations of Ca2+ and HCO3− in most springs increased obviously before the Mojiang M5.9 earthquake but decreased after the earthquake. Changes also occurred in the reservoir temperatures of some spring samples. These hydrogeochemical variations might be attributable to accelerated water-rock interactions and/or the mixing of second fluids due to the earthquake.

Late Palaeozoic and Cenozoic magmatism, including Pingbian Quaternary basaltic volcanoes, occurs in southeast Yunnan, China, where seismic tomography evidence indicates magma activity in the uppermost mantle. However, the characteristics of mantle fluid release remain poorly understood. Here, we report the chemical compositions of hot spring gases in SE Yunnan and measure the He-3/He-4 ratios, He-4/Ne-20 ratios, and delta C-13-values (CO2, CH4) to determine their origins and the factors influencing their migration. Except for five samples contaminated by the atmosphere (He-4/Ne-20 ratios, 0.39-2.39), the Rc/Ra ratios (Rc is the air-corrected He-3/He-4 ratio, Ra is the air ratio with 1.4 x 10(-6)) range from 0.042 Ra to 0.470 Ra, indicating that the helium is mostly of crustal origin with minor addition of mantle-derived helium. The calculated maximum proportion of mantle helium was similar to 5% of total helium, indicating that mantle 3He leakage correlates with the ductile lower crust. The hot spring gases are fractionated by the partial dissolution of CO2 in groundwater, and the initial delta(CCO2)-C-13 values are modelled by Rayleigh fractionation within a range of -26.5%degrees to -6.14%degrees. The modelled CO2 in samples estimated by the He-C isotope coupling model originates from the mixing of limestone and organic sediment end-members. The isotopic signature of CH4 (-69.2%degrees to 35.9%degrees) suggests a thermogenic source and microbial oxidation in some samples. Furthermore, the apparent isotopic temperatures are estimated using fractionation factors for CH4 and CO2, suggesting a lack of magmatism in the crust beneath the Red River fault zone (188-318 degrees C), but partial melting under the Bozhushan granitoid plutons (572-688 degrees C). The low emission of mantle-derived helium is attributed to the low fault permeability and minor active crustal deformation in present-day SE Yunnan, which restrain the upward migration of mantle fluids. (C) 2020 Published by Elsevier B.V.

为探讨云南省香格里拉市下给和天生桥温泉水化学和逸出气CO2的变化特征与其周边断裂及2013年香格里拉Ms5.9地震之间的关系,对比研究了1981,2004,2013,2016和2017年这2处温泉水化学分析测试数据,利用2004和2017年2处温泉的逸出气体组成和He,C同位素数据分析逸出气CO2释放情况和来源.结果 表明:下给和天生桥温泉在香格里拉Ms5.9地震前后Ca2+,Mg2+和游离态CO2含量有由低变高、再变低的变化.2处温泉逸出气体皆显示高含量的CO2释放,但2017年释放含量有所减少,且He,C同位素皆存在幔源入侵的特征.

大量的地球物理资料表明,大陆内部孕震层底界普遍存在流变层(中下地壳).除解耦作用外,底界流变层的活动可能对上覆地壳的地震孕育有驱动作用,因此,底界流变层的物理化学状态变化可能对了解地震孕育过程有重要的监测价值.

为了解决以断层为中心的思想在分析中国地震在空间上的变迁、地震前兆的时空分布以及地震前后应力场的演化上遇到不少困难的问题,以块体为中心研究地震的想法被提了出来.我国大陆几乎所有8级和80％—90％的7级以上强震发生在活动地块边界带上,表明地块间的差异运动是大陆强震孕育和发生的直接控制因素.

大量研究表明,强震活动与地温梯度、居里等温面、大地热流、水热活动、地震波速度结构等岩石圈物理状态的高值异常区并不重合,而是分布在异常梯度带上或两高值异常区中间过渡带上.岩石圈的物理特征变化均与深部地热活动有着密切关系,地热活动或热状态的改变对孕震区介质的物理和化学性质都有着重要的影响,是触发大地震的重要因素.

介绍了地壳流体CO2的3个主要成因:有机成因、变质成因及幔源成因,并着重讨论了CO2气体的稳定同位素13C的示踪性能;总结了由地壳释放CO2的主要方式、上升通道及其存在形态.在回顾地壳流体CO2等释放在目前地震监测、预报及相关研究中的主要研究进展的同时,指出地壳深部流体(CO2、He、CH4等)在同位素地球化学、深源流体运移与地震活动、深源流体对震源介质的影响等.此外,提出对深源流体监测不能仅限单一组分(CO2)的监测,需多种深源成分(He、Ne、Ar、H2、CH4)同时监测.

小江断裂带属现今仍在活动的断裂,同时也是一条破坏性地震多发带.为探究特定地区的地球化学场与地震的耦合关系,寻找特定的前兆观测组分,笔者选取并计算了小江断裂带及邻近地区的95处温泉的热储温度.利用温泉的水化学数据(K+、Na+、Ca2、Mg2、SO42-、Cl-、HCO3-),结合该区域的构造特征及地震活动规律,对温泉的水化学、水温、热储温度、稳定同位素(δ13C,3He/4He)等地球化学特征进行了研究.结果表明温泉中主要离子含量、TDS含量、水温及热储温度的高值区域在空间上主要沿小江断裂带展布,且呈北高南低的分布特征.水温和热储温度高值区内中强地震(M≥4.7)分布少;相反,低值区内中强震活动频繁,且强度相对较大.碳、氦同位素特征显示,CO2气体的碳同位素(δ13C)组成具有明显的生物成因特征;幔源氦(百分含量)同素所占比例相对较低,表明小江断裂带中南段壳幔连通程度低,脱气作用几乎都发生在地壳范围.

On the basis of the regional seismotectonic background,the neotectonic movement and the regional tectonic stress field of Yingjiang and its adjacent area,we preliminarily analyzed the tectonic activity characteristics of Yingjiang MS5.8 earthquake with the aspects of the intensity isoseismal line,the earthquake sequence,the surface deformation belt and the focal mechanism solution.The results show that the sinistral strike-slip activities of Dayingjiang Fault in NE trend triggered the Yingjiang MS5.8 main shock,and the main shock and foreshock sequences reflected the characteristic of the conjugate rupture activity of the Dayingjiang Fault in NE trend and Sudian-Yingjiang Fault in NS trend.Combined with the regional historical earthquake situation and seismic activity before and after Yingjiang MS5.8 main shock,we preliminarily discussed the seismic activity characteristics in Yingjiang region and got the conclusion that the earthquake swarm was the main feature of the seismic activity in Yingjiang region,and the occurrence of Yingjiang MS5.8 is the result of continued-enhanced activity of MS4.0earthquakes swarm in early 2011.

Appling the Shakemap site correction methods of U.S. for the rapid prediction of ground motion intensity and seismic intensity in Yunnan,we analyzed Shakemap site correction method and its main points,and applied it to the comparison and analysis of typical regions in Yunnan and the actual site conditions,and discussed the relevant parameters problems of it. We should improve the relevant parameters of Shakemap site correction method in Yunnan. Firstly,we supplied the classification of site conditions only based on topographic slope single indicator,which should be considered the correlation between V30S and multi-index factors (such as the near-surface geological conditions,elevation,the distance from the river etc.).At the same time,we must consider the impact of local site conditions on ground motion in the actual site conditions and modified the amplification of local site conditions on ground motion from the soft soil of basin,the geological structure and the local sand liquefaction sites etc. Basing on the theoretical calculation results,combining with modifying actual site conditions,we could improve the precision of predicted results by double correction of theoretical and practical,which could provide useful information and help for emergency decision after the earthquake.

Both deep seismic sounding (DSS) and magnetotelluric sounding (MT) data suggest that there exist still magma chambers within crust in Tengchong volcanic field (TVF) present-day, but there are differences on their number and spatial distribution and their complete picture still lack good understanding. MT data suggests that TVF is an asthenosphere-upwelling and lithosphere-thinning area, but the spatial extent of the thinning area still lack adequate constraints. By sampling, istopic analyzing of free gases from thermal springs in TVF and its periphery area, and utilizing some previous investigation data, we obtain He/He ratio data of 75 thermal springs. By atmosphere contamination correcting, mantle-derived proportion calculating and spatial interpolation, we obtain spatial distribution map and time diagram of release intensity of mantle-derived volatiles in TVF. After investigating the characterization of spatial and temporal distribution of mantle-derived helium release according helium isotope tracing principle, we found that there are 1 band and 3 blocks of high He/He ratio in spatial distribution pattern in TVF. With He/He ≥ 1 Ra (Ra denotes the atmospheric He/He ratio value, 1. 39 X 10), mantle-derived helium proportion ≥ 15% as boundary conditions, the abnormal release area of mantle-derived volatiles in TVF shows an entire zonal area, which is a north-south strike strip, north to south 100km long, east to west 50km wide. In the whole piece of abnormal area inside, the intensity of mantle-derived volatile release can be divided into 3 different areas. (J) The Tengchong County-Rehai and periphery in central TVF, where the He/He ratio reaches more than 5. 5Ra, the mantle-derived helium proportion above 70%, are the most strong release area. (2) The Qushi and periphery in north TVF, where the He/He more than 4. 5Ra, the mantle-derived helium proportion more than 50%, are second strong release area; (3) The Wuhe-Puchuan-Xinhua in southern TVF, where the He/He more than 2Ra, the mantle-derived helium proportion more than 25%, are the weakest release area. In temporal distribution pattern, mantle-derived volatiles release intensity in TVF has been incresing, and the rate of He/He ratio (Ra) increasing in the 3 rd releases area is significantly larger than the other two. Our results suggest that, the spatial distribution pattern of intensity of mantle-derived volatiles release in TVF is the most direct reflection of the spatial scale and intensity of asthenosphere upwelling (lithospheric thinning) in the region, the size of thinning zone is roughly north to south 100km long, east to west 50km wide. There are 3 magma chambers within crust in TVF. The 1 st one locates beneath Tengchong County-Rehai area, the 2 nd one locates beneath Mazhan-Qushi area, and the 3 rd one locates beneath Wuhe-Longjiang-Tuantian-Puchuan-Xinhua area. These 3 magma chambers constantly being fed with mantle melt materials, among which, it is the most obvious for the 1 st one to be fed continuously with mantle melt materials. The 1 st magma chamber, which concentrates mantle-derived volatiles release, relative geothermal gradient, deformation and seismicity and so on abnormal in one, being accepting feeding from mamtle-derived magma, being of strongest activity, most likely to erupt, needs the key surveillance. The 2 nd magma chamber, which release intensity of mantle-derived volatiles is also noticeable, also being possibly accepting feeding from mamtle-derived magma, should be strengthened in monitoring. The 3 rd magma chamber, which has the biggest size, and is shallowest, where the current feeding of mantle-derived magma increased quickly, is must be paid some attention.

Both deep seismic sounding(DSS) and magnetotelluric sounding(MT) data suggest that there exist still magma chambers within crust in Tengchong volcanic field(TVF) present-day,but there are differences on their number and spatial distribution and their complete picture still lack good understanding,MT data suggests that TVF is an asthenosphere-upwelling and lithosphere-thinning area,but the spatial extent of the thinning area still lack adequate constraints,By sampling,istopic analyzing of free gases from thermal springs in TVF and its periphery area,and utilizing some previous investigation data,we obtain 3He/4He ratio data of 75 thermal springs,By atmosphere contamination correcting,mantle-derived proportion calculating and spatial interpolation,we obtain spatial distribution map and time diagram of release intensity of mantle-derived volatiles in TVF,After investigating the characterization of spatial and temporal distribution of mantle-derived helium release according helium isotope tracing principle,we found that there are 1 band and 3 blocks of high 3He/4He ratio in spatial distribution pattern in TVF,With 3He/4He≥1Ra(Ra denotes the atmospheric 3He/4He ratio value,1.39×10-6),mantle-derived helium proportion≥15% as boundary conditions,the abnormal release area of mantle-derived volatiles in TVF shows an entire zonal area,which is a north-south strike strip,north to south 100km long,east to west 50km wide,In the whole piece of abnormal area inside,the intensity of mantle-derived volatile release can be divided into 3 different areas,① The Tengchong County-Rehai and periphery in central TVF,where the 3He/4He ratio reaches more than 5.5Ra,the mantle-derived helium proportion above 70%,are the most strong release area,② The Qushi and periphery in north TVF,where the 3He/4He more than 4.5Ra,the mantle-derived helium proportion more than 50%,are second strong release area;③ The Wuhe-Puchuan-Xinhua in southern TVF,where the 3He/4He more than 2Ra,the mantle-derived helium proportion more than 25%,are the weakest release area,In temporal distribution pattern,mantle-derived volatiles release intensity in TVF has been incresing,and the rate of 3He/4He ratio(Ra) increasing in the 3rd releases area is significantly larger than the other two,Our results suggest that,the spatial distribution pattern of intensity of mantle-derived volatiles release in TVF is the most direct reflection of the spatial scale and intensity of asthenosphere upwelling(lithospheric thinning) in the region,the size of thinning zone is roughly north to south 100km long,east to west 50km wide,There are 3 magma chambers within crust in TVF,The 1st one locates beneath Tengchong County-Rehai area,the 2nd one locates beneath Mazhan-Qushi area,and the 3rd one locates beneath Wuhe-Longjiang-Tuantian-Puchuan-Xinhua area,These 3 magma chambers constantly being fed with mantle melt materials,among which,it is the most obvious for the 1st one to be fed continuously with mantle melt materials,The 1st magma chamber,which concentrates mantle-derived volatiles release,relative geothermal gradient,deformation and seismicity and so on abnormal in one,being accepting feeding from mamtle-derived magma,being of strongest activity,most likely to erupt,needs the key surveillance,The 2nd magma chamber,which release intensity of mantle-derived volatiles is also noticeable,also being possibly accepting feeding from mamtle-derived magma,should be strengthened in monitoring,The 3rd magma chamber,which has the biggest size,and is shallowest,where the current feeding of mantle-derived magma increased quickly,is must be paid some attention.

Temperature is an important physical parameter of magma. It has important theoretical and practical significance to acquire and monitor temperature parameter of magma chambers for better understanding changes in the physical and chemical properties and behavior of a volcano, and for better assessing its activity and eruption risk. Here we report the carbon isotope composition data of CO 2 and CH 4 that collect from thermal springs in the Tengchong volcanic field ( TVF) and the temperatures of the existing three magma chambers within crust beneath the TVF, which, are calculated with carbon isotope equilibrium fractionation equation T(K) =3880. 3 ( 1000Inα(CO 2-CH 4, ) -0.5984 between CO 2 and CH 4 that fit from Horita' s experimental correction of Richet's s theoretical fractionation factor data between them. Our results show that, the lowest carbon isotope equilibrium fractionation temperature between CO 2 and CH 4 of gas source area, is 397°C, the highest one, up to 1163°C, the average value, 615°C in the TVF and that, among the 3 crustal magma chambers in the TVF, the southern Wuhe-Longjiang-Puchuan one has highest present-day temperature, which ranges from 464°C to 1163°C , with an average of 773°C ; the central Tengchong-Heshun-Rehai one has higher temperature, which ranges from 438°C to 773°C, with an average of 5661 ; the northern Mazhan-Qushi-Yongan one has the lowest temperature, which ranges from 397°C to 651°C , with an average of 524°C. We believe that the current temperature of the gas-rich region at the top of those 3 magma chambers in TVF varies from 400°C to 1200°C, the actual average temperature of those 3 magma chambers should be higher than 615°C , the temperature of the core of those 3 magma chambers may be 700 ∼ 1200°C , that of marginal region of those 3 magma chambers may be 400 ∼ 600°C. The current temperature of the center of those 3 magma chambers has reached which rhyolitic magma ( 600∼ 900 °C ) , andesitic magma (800 ∼ 1100°C) and basaltic magma (1000 ∼ 1250°C) form in, suggesting further, in turn, that there exist objectively those 3 magma chambers in TVF. In addition, we find that, in the process of determining whether the carbon isotope fractionation equilibrium between CO 2and CH 4 achieve or not with the δ-Δ diagram method, under the conditions that the slope sign of two fitting straight lines maintain always the opposite, no matter how exclud data points, one can not make the difference b Δ of the intercept b CO2 of δ 13 Cco 2,-δ co2 -CH4 fitting straight line in the δ -axis and the intercept b CH 4 of δ 13 CCH 4,-δ co2 -CH4 fitting straight line in the δaxis less than 0. 1245, indicating that the intersection point of the two fitting straight lines can not fall in the δ-axis. And this value is near the constant item of Horita' s equation, sugestting that there exists really a constant item in the equation of carbon isotope fractionation equilibrium between CO 2 and CH 4, and that the carbon isotope fractionation between CO 2 and CH 4 exists allways at no matter how high temperature. The δ-Δ diagram guidelines of determining the carbon isotope fractionation equilibrium between CO 2 and CH 4 should be amended as follows : under the conditions that the sign of the slope of the two fitting lines keep allways opposite, the δ 13 CO 2-Δ CO2-CH 4 fitting straight line and the δ 13 C CH4,- δ co2 -CH4 fitting straight line should intersect near the δ-axis with intercept difference 0. 1245.