The first identification of hydrogeochemical indicators of mud volcanic activity

Hydrogeochemical monitoring has been implemented at a mud volcano for the first time in the world. Measurements were carried out during the field season of 2015 at five gryphons of the South Sakhalin mud volcano with various degrees of activity. Statistically significant differences in the chemical compositions of mud-volcano waters from different gryphons are established. These differences are determined by the activity of the gryphons.     

Isotopic-geochemical characteristics of free gases of the South Sakhalin mud volcano and their relationship to regional seismicity

This paper discusses the results of long-term monitoring observations on the chemical and isotopic composition of free gases in gryphons of the South Sakhalin mud volcano on Sakhalin Island. It was shown that during seismic activation in the region, the chemical composition of free gases changes, whereas the isotopic composition of carbon in methane and carbon dioxide remains constant. A possible interpretation of the obtained data was suggested. The depth of the gas reservoir that supplies the South Sakhalin mud volcano was estimated as well.     

On the problem of variability in the chemical composition of mud–volcanic waters: Evidence from the Yuzhno-Sakhalinsk mud volcano

The results of hydrogeochemical observations on the Yuzhno-Sakhalinsk mud volcano in 2010–2014 are considered. The chemical analysis of samples of mud–volcanic waters was carried out at various analytical centers, which is similar to the common situation where hydrochemical data for a volcano are obtained by different researchers. It is shown that the chemical composition of the mud–volcanic waters is relatively stable in time and space (for different gryphons of the volcano). This allows us to determine the characteristic range of hydrogeochemical indicators. For each year of observations, the coefficients of variation for the concentrations of Na, Mg, Ca, K, and HCO₃ mostly range from 10 to 30%. However, the concentrations analyzed in individual samples may differ significantly from each other. These natural variations are a likely source of errors in the interpretation of hydrochemical data. In addition, it is necessary to account for the specifics of mud–volcanic waters as an object of analytical chemical investigations.     

Dynamics of the gryphon activity of gas-water lithoclastic (Mud) volcanoes and their relation to the natural seismicity as exemplified by Yuzhno-Sakhalinsk volcano (Sakhalin Island)

This paper reports detailed evidence on the dynamics of the gryphon activity of the Yuzhno-Sakhalinsk gas-water lithoclastic (mud) volcano. It was obtained by visual observations during periods between the short-term eruptions of 1959, 1979, and 2001 and, especially, during continuous monitoring between June 18 and September 3, 2005. In addition to the direct observations, the monitoring included measurements (three times per day) of the air temperature and pressure, the temperature of the liquid lithoclastic mass filling the crater hollows of several gryphons of various types, and the amounts of gases released by the two largest and most active gryphons. Liquid lithoclastic mass was collected daily in the crater of the largest (main or central) gryphon for the subsequent ICP AES analysis for five elements (Al, Fe, Ca, Mn, and Ba). The results of the monitoring were compared with the measurements of natural seismicity using the system of Dat and Datamark digital seismic stations. The acquired information was used to unequivocally demonstrate the existence of a direct causal relation between the activity of the Yuzhno-Sakhalinsk mud volcano, the dynamics of the chemical composition of the liquid lithoclastic mass ejected from its main gryphon, and the regional and local natural seismicity, which was previously conjectured. The dynamics of one of the measured elements (Al) is potentially useful for the prediction of eruptions.     

CONTRIBUTION TO THE GEOCHEMISTRY OF CRUDE OILS AND GASES FROM THE MUD VOLCANO ZONE OF THE KEYMIR-CHIKISHLYAR AREA OF WESTERN TURKMENIA

The paper describes crude oils and gases from mud volcanoes and oils and gases from producing horizons at depth in the same area. It is shown that the mud volcano gases and oils (the oils particularly) can be correlated with those in strata from 500 m. to more than 2,600 m deep. The mud volcano gases are somewhat modified by hypergene processes. Analytical data in tabular form is given.--B. W. Nelson.     

地震的超临界水流体退相爆发成因——以汶川大地震震中“爆裂式泥火山”场景为例

汶川地震震中＂爆烈式泥火山＂引发Ms8.0大地震,造成巨大破坏和惨重损失,但此多点的泥火山群场景,较2009年提名为＂世界最有价值自然遗产——爱沙尼亚泥火山＂,更具人类解密地内超临界水流（熔）体奥秘的典型意义。5.12地震中泥火山（群）的地下深处,临震前聚集能量的超临界流体（SCW）,与常态水比较,它在壳幔地体中,表明张力和粘度极低,扩散迁移能力极强;密度、热导率、电性能、比热容及对地内物质的溶解力均有成百至数千倍的差异;巨大的内能;在临瞬间爆发退相,造成体积流率达N×109m3的气流动能等,SCW的这一切自燃特征决定了他是地震的成因,也是地内壳幔中一切内生地质作用的原动力。SCW引发的地震分为三类：主震有喷发活动的汶川型泥火山-地震（包括：2009—3—18汤加浅海边气火山伴Ms7.9地震）、主震无喷发活动的唐山型（包括中源深源地震）及主要在深海喷发海啸-地震（印尼2004-12-26海啸伴8.7级地震）。SCW为高温高压热流体,它的大量运移,集聚地及临震减压排气进而退相爆发等特点,采用当代地球物理探测技术,至少对浅源的SCW＂看得见、摸得着＂,成功短临预报现实用地-空红外探测技术即可实现。     

Regional and local geothermal conditions in the northern Black Sea

More than 100 new heat flow measurements have been collected in recent years (2002–2004) in different tectonic environments of the northern Black Sea. The northern periphery of the Black Sea is characterized by strong geodynamic and seismic activity, high sedimentation rates, diapiric structures, mud volcanism, and fluid and gas escape at the sea floor. We present new thermal data from the shelf, continental slope and deep-water basin, measured off-shore using a marine thermo-probe and on-shore in drill holes. Heat flow density ranges from 20 to more than 2,000 mW/m². For two local areas (the Dnieper gas seeps and the Dvurechenski mud volcano area), we discuss the relation between heat flow variability and the geological and physical processes in the near-bottom sediment layer. The Dnieper gas seeps area is characterized by strong small-scale heat flow variability and is controlled by fluid and gas migration. In the Dvurechenski active mud volcano, the near-bottom temperature in sediments is anomalously elevated because additional heat is carried out by mass flows of fluids and clay minerals. Away from the mud volcano heat flow quickly decreases to background values.     

Geochemical and geo-electrical study of mud pools at the Mutnovsky volcano (South Kamchatka,Russia): Behavior of elements,structures of feeding channels and a model of origin

This study presents data on the geochemical composition of boiling mud pools at the Mutnovsky volcano. The physicochemical characteristics of the pools and the concentrations of major, minor and trace elements in pool solutions vary widely. A comparison of the geochemical compositions of host rocks and solutions indicates that leaching from rocks is not the only source of chemicals in thermal solutions. Geophysical studies reveal the inner structure of thermal fields, which reflect the shapes of the underground reservoirs and feed channels. Using geophysical methods (electrical resistivity tomography and frequency domain investigations), it was shown that the vertical structure and complex geochemical zonation of the feed channels leads to a high contrast in the compositions of the mud solutions. These findings answer questions about the origin and composition of surface manifestations. To elucidate the mechanisms of solution formation, an attempt was made to describe the magmatic fluid evolution and the resulting mixing of waters by physical and mathematical models. The model illustrates fluid migration from a magma chamber to the surface. It is shown that the formation of brines corresponding to the mud pool composition is possible during secondary boiling.     

台湾西南部乌山顶泥火山的成因机制初探

乌山顶泥火山位于台湾西南部旗山断层沿线.由于台湾西南部具有独特的地质构造背景,沿着古亭坑背斜和旗山断层沿线分布了许多泥火山.本文以乌山顶泥火山为例,研究泥火山的成因.在了解泥火山地质背景、活动现状的基础上,分析了喷出物的矿物组成、古生物组合、流体地球化学特征.喷出的主要矿物有石英、伊利石、高岭石-蒙脱石混层矿物、伊利石-蒙脱石混层矿物,古生物有Reticulofenestra minuta、 Sphenolithus abies等,流体中的离子主要是Cl-、Na+等.由此探讨了泥浆来源和成因机制,认为泥火山的活动与深部古亭坑组地层存在异常高压有关,构造活动是泥火山活动的主要诱发因素.     

泥火山——天然气水合物存在的活证据

海底天然气水合物大多与通过切穿沉积盖层的断裂的上升烃类流体相关，这些高渗透带包括泥火山和底辟等侵入构造，所以泥火山、底辟和海底断裂等构造周围可能赋存水合物；实际钻探结果也证实，泥火山和水合物的形成与聚集有较为密切的关系。泥火山，它是地层内部圈闭气体由于压力释放上冲的结果，也是气体向上运移的通道。文章初步总结了泥火山与水合物的成矿关系，认为泥火山是水合物赋存的标志之一，是水合物存在的活证据。本文对我国泥火山与水合物的发育和赋存进行了分析预测，并对泥火山构造中水合物的成矿模式进行了初步探讨。     

Deep structure of the Yuzhno-Sakhalinsk mud volcano: Results of multidisciplinary seismic surveys

The paper presents the results of multidisciplinary seismic surveys carried out by refraction and reflection methods for compressional and shear waves on Yuzhno-Sakhalinsk mud volcano. A large extinct (approximately 60–70 years ago) volcano was identified near the active volcano, and its structure was studied. It was found that the recognized intermediate fluid-bearing chambers correlate with the distinguished tectonic dislocations. A supposition was made that the mud volcanism is sequentially developed in the northeastern direction and related to the modern tectonics of the Central Sakhalin Fault.     

羌塘盆地现代泥火山的发现及其油气地质意义

在羌塘盆地唢呐湖地区发现现代泥火山,通过采集泥浆样、水样等样品,开展水化学离子、水溶烃类气体、碳氢氧稳定同位素等测试分析,对现代泥火山的油气地质意义进行了探讨。水化学类型和氢氧同位素表明,该地区地下可能存在油气藏;水溶烃类气体测试结果表明,气体成分为C1~C5,以甲烷为主,与常规气藏的气体成分一致;碳同位素判别结果表明,其为热解成因的油成气。结合泥火山的地质背景,表明泥火山为油气藏破坏渗漏的产物,在保存良好的未泄露地区,油气勘探具有良好前景。     

Gases of mud volcanoes in the Copper River Basin,Alaska

The gases emitted from mud volcanoes in the Copper River Basin of Alaska fall into two distinct types which are not mixed during vertical migration. The gases in the eastern volcanoes are nearly pure carbon dioxide, whereas the western ones contain methane and nitrogen and almost no carbon dioxide. Chemical and carbon isotopic compositions suggest the carbon dioxide rich gases originated by solution of limestones and that methane rich gases probably formed by thermal decomposition of coals.Permafrost may be a strong factor in separating the Copper River Basin gases. Extending downward for several hundred feet, the permafrost would prevent shallow lateral migration and focus the energy of the gas into occasional mud volcano vents. Soil gas analyses show rapidly decreasing amounts of the methane to about 150 m and of carbon dioxide to about 20–40 m away from the mud volcano pools. Isotopic variations of these natural methane and carbon dioxide gases, which are not intermixed, indicate that calculations of formation temperatures based on δ¹³C ratios cannot be used generally.     

泥底辟输导流体机制及其与天然气水合物成藏的关系

摘要：详细阐述不同成因的泥底辟流体输导模式,探讨了泥底辟输导体系的演化与天然气水合物成藏之间的关系,并分析神狐海域泥底辟输导体系对天然气水合物成藏的影响。底辟核外部伴生断裂、底辟核内部流体压裂裂缝和边缘裂缝带均可作为输导流体的通道。根据运移通道和动力等差异性,提出泥底辟输导流体的2种端元模式：超压-流体压裂输导型和边缘构造裂缝输导型。在此基础上,讨论了泥底辟(泥火山)的不同演化阶段对水合物的形成、富集和分解的影响。早期阶段,泥底辟形成的运移通道可能未延伸到水合物稳定带,导致气源供给不够充分;中期阶段,水合物成藏条件匹配良好,利于天然气水合物生成;晚期阶段,泥火山喷发引起水合物稳定带的热异常,可能导致水合物分解,直至泥火山活动平静期,水合物再次成藏。神狐海域内泥底辟分为花冠状和穹顶状两类,花冠状泥底辟以超压-流体压裂输导型为主;穹顶状泥底辟以底辟边缘裂缝输导型为主。泥底辟输导体系的差异性可能是神狐海域天然气水合物非均质分布的影响因素之一。 关键词：泥底辟;输导体系;天然气水合物;成藏机制;神狐海域     

基于因子分析法和最小数据集的五大连池火山矿泥质量评价

火山矿泥是一种于严苛条件下历经数百年形成的珍稀矿产资源,目前尚无判定及评价其质量的方法.本研究采用因子分析法及最小数据集理论构建火山矿泥质量评价方法,并对五大连池风景区内火山矿泥质量进行综合评价.研究结果表明：火山矿泥质量评价最小数据集包括V、Al、含水量、黏粒,将五大连池火山矿泥分为4个质量等级,其中I级火山矿泥的储量最大,约占总储量的一半.新期火山周边火山矿泥质量最好,西部火山周边的火山矿泥质量整体优于东部.     

Geochemical characteristics of mud volcano fluids in the southern margin of the Junggar basin,NW China: implications for fluid origin and mud volcano formation mechanisms

Mud volcanoes can provide important information about the underlying strata, hydrocarbon accumulation, and recent neotectonic movements in an area. The fluids erupting from mud volcanoes provide important information about their formation and evolution. The ion concentration and the hydrogen and oxygen isotopes of the fluids that were erupted from the three mud volcano groups, Baiyanggou, Aiqigou, and Dushanzi, and nearby rivers in the southern margin of the Junggar basin, northwestern China, are studied. The concentrations of Na and Cl in mud volcano fluids are clearly elevated, displayed as the Na-Cl type. The δD and δ18O values of the fluids are similar between the Baiyanggou and Dushanzi mud volcanoes, which are mainly from ancient sedimentary pore water. However, the Aiqigou mud volcano is depleted in dissolved Cl and shows lower δ18O values with mixed sources, including deep pore and local meteoric water. Two types of mud volcanoes are proposed in this study. One type is low-energy mud volcanoes with a low volume of fluid of deep origin on the hillcrest, which display as mud pool/pie/hole. The other type is high-energy mud volcanoes having mixed fluid origin in the valley and formed in the shape of a mud cone (dome).     

Active mud volcanoes on- and offshore eastern Makran, Pakistan

To study the activity, source and driving force of the venting of fluidized mud in the coastal Makran, we carried out reconnaissance surveys of two active onshore mud volcano fields (Chandragup and Jebel-u-Ghurab) and of a newly born (March 1999) offshore mud volcano (Malan Island). All studied on- and offshore mud volcanoes line up along one southwest/northeast-trending structural lineament, the axis of the Dhak Anticline. Isotopic data point to a bacterial origin of the gas (mainly methane). Mixed benthic foraminiferal faunas and calcareous nannofloras suggest that the source level of the extruded mud is at a sub-surface depth of 2-3 km. Observed mud discharge varied between 0 and 1.4 m³ h^-1 and gas discharge rates between negligible amounts to 1 m³ s^-1. Mud temperatures in the crater lake of Chandragup I are near-ambient temperatures. They rise slightly (Б.5°C) during episodes of modest mud outflow. An area of 160,000 m³ of soft mud was vigorously extruded from the sea floor at a water depth of 10 m within days after 15 March 1999, forming Malan Island. The island was destroyed within a few months after its birth by deep-reaching wave action during the SW monsoon. This was possibly aided by local subsidence of the mud volcano structure due to the volume loss following rapid degassing and mud extrusion.     

Methane and sulfide fluxes in permanent anoxia: In situ studies at the Dvurechenskii mud volcano (Sorokin Trough, Black Sea)

The Dvurechenskii mud volcano (DMV) is located in permanently anoxic waters at 2060 m depth (Sorokin Trough, Black Sea). The DMV was studied during the RV Meteor expedition M72/2 as an example of an active mud volcano system, to investigate the significance of submarine mud volcanism for the methane and sulfide budget of the anoxic Black Sea hydrosphere. Our studies included benthic fluxes of methane and sulfide, as well as the factors controlling transport, consumption and production of both compounds within the sediment. The pie-shaped mud volcano showed temperature anomalies as well as solute and gas fluxes indicating high fluid flow at its summit north of the geographical center. The anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SR) was repressed in this zone due to the upward flow of sulfate-depleted fluids through recently deposited subsurface muds, apparently limiting microbial methanotrophic activity. Consequently, the emission of dissolved methane into the water column was high, with an estimated rate of 0.46 mol m⁻² d⁻¹. On the wide plateau and edge of the mud volcano surrounding the summit, fluid flow and total methane flux were lower, allowing higher SR and AOM rates correlated with an increase in sulfate penetration into the sediment. Here, between 50% and 70% of the methane flux (0.07-0.1 mol m⁻² d⁻¹) was consumed within the upper 10 cm of the sediment. The overall amount of dissolved methane released from the entire mud volcano structure into the water column was significant with a discharge of 1.3 × 10⁷ mol yr⁻¹. The DMV maintains also high areal rates of methane-fueled sulfide production and emission of on average 0.05 mol m⁻² d⁻¹. This is a difference to mud volcanoes in oxic waters, which emit similar amounts of methane, but not sulfide. However, based on a comparison of this and other mud volcanoes of the Black Sea, we conclude that sulfide and methane emission into the hydrosphere from deep-water mud volcanoes does not significantly contribute to the sulfide and methane inventory of the Black Sea.     

Mud Volcanoes: Distribution Regularities and Genesis (Communication 2. Geological–Geochemical Peculiarities and Formation Model)

The work discusses relationships between mud volcanoes, tectonic faults, folds, and oil-and-gas deposits. The location of roots and centers of mud volcanic activity is analyzed. It proposes a new model of mud volcano formation, according to which these structures result from the development of elision systems of sedimentary basins.     

Fluid migration and origin of a mud volcano in the Northern Apennines (Italy): the role of deeply rooted normal faults

ABSTRACT In the foothills of the Northern Apennines mud volcanoes are locally aligned along active normal faults, which allow surface leakage of fluids derived from deep sources (>3–6 km). The chemical and isotopic analysis of the fluids of a mud volcano, coupled with the reconstruction of its geological setting, allowed an investigation of the processes of migration and fluid flow. The fault system associated with the Regnano mud volcano drains a deep Miocene reservoir (foredeep marine deposits), which supplies formation water and thermogenic methane that has migrated from underlying Mesozoic carbonates. The muds from the volcano contain late Eocene microfossils and are extruded only during paroxysmal events. They have a shallower origin (about 1 km) from the base of Tertiary marine deposits deposited upon the upper tectonic nappe of the chain (Ligurian unit). This case study suggests that normal faults are very effective in controlling surface emissions.