Modeling of Stress Changes at Mayon Volcano,Philippines

In this paper, we analyze the stress change associated with the inverted volcanic source models at Mayon volcano, Philippines, where there are gravity changes without significant deformation after the 1993 eruption. We detail the applicable data and the associated inversion techniques and models prior to calculating the appropriate stress changes. It is determined that the stress change associated with the central magmatic source produces compressional stress changes at a secondary source to the northwest, prompting a change in the local water storage in the underlying fractured rock.     

Continuous,Direct Gas-Geochemical Monitoring in Hydrothermal Vents: Installation and Long-Term Operation on Nisyros Island (Greece)

In this paper the installation and long-term operation of a system for continuous monitoring of fumarolic gases is described. Several physicochemical and gas-geochemical parameters such as the concentration of CO₂, H₂S and CO in the fumarolic emissions, as well as the temperatures of the hydrothermal steam and soil in close vicinity of the fumarole and steam pressure are measured in short-time intervals (typically 15 seconds). Data are logged on-site and in parallel transferred to a remote station by digital telemetry. Specially developed software enables the real-time observation of the local conditions in the crater and full bidirectional control of the monitoring system. Fluctuations in the monitored parameters are also reported. From the data presented it can be concluded that environmental conditions (direction and strength of wind, precipitation) will interact with some of the parameters monitored. These influences can only be revealed by continuously operated monitoring systems.     

河北沽源—多伦地区中生代含铀火山岩地球化学

沽源和多伦地区是燕辽多金属成矿带的重要组成部分，中生界主要发育上侏罗统白旗组、张家口组，下白垩统大北沟组和花吉营组。张家口组火山岩分布广、厚度大，是铀（钼）矿床的主要含矿主岩。中生代火山岩属于钙碱性系列，化学成分富硅、偏碱，δ值1.17-7.60。稀土元素特征反映火山岩有壳幔混合和壳源改造两种成因。火山岩形成于弱造山环境，其年龄与库拉—太平洋板块向亚洲板块俯冲的时间吻合。张家口组酸性火山岩具有我国相山产铀火山杂岩富硅、富钾，铕极亏损的地球化学特征。     

吉东火山岩型金矿地质特征及流体包裹体研究

通过对主要金矿床的流体包裹体 ,S、C、H和O同位素特征研究分析 ,认为金成矿的物化环境 :温度为 15 6～ 2 84℃、压力小于 6 6 0× 10 5Pa (深度不超过 2km) ;成矿流体具有富含H2 O、SO2 - 4、Cl- 和高K+的特点 ,是岩浆热液和大气降水的混合流体 ;成矿物质主要来源于火山 次火山岩     

上黑龙江断陷火山岩特征及岩金找矿方向

研究区处于上黑龙江断陷盆地中段，中生代火山岩出露面积广泛，区内12处岩金矿床（点）均与中生代火山活动有关，塔木兰沟期和上库力期火山岩是成矿的岩体标志，3期火山岩均属碱性系列，以富Zr,Ti,Cr,P及轻稀土富集型为特征。硅化，绢云母化，绿泥石化，黄铁矿化，黄铜矿化。方铅矿化和褐铁矿化是找矿的蚀变标志，断陷盆地边缘和推覆构造边缘，火山带交汇部位，NE或NNE向断裂与其他方向断裂交汇部位以及火山机构周围的环状，放射状断裂是成矿的有利部位。     

试论斑岩铀矿成矿系列

本为作多年来在火山岩型铀矿领域的工作总结。章详细论述了斑岩铀矿成矿系列的特征，认为大部分火山岩型铀矿床的形成与火山活动晚期、最晚阶段的岩有着密切的关系。这些斑岩主要是花岗斑岩、霏细斑岩、石英斑岩。     

北祁连山东段新元古代火山岩的年代学证据

在1∶5万石门川幅、老龙湾幅区域地质调查时发现,北祁连山东段上吊吊坡地区存在一套不同于下奥陶统阴沟群的火山岩,经全岩样品Sm-Nd同位素测定,获得Sm-Nd等时线年龄为(723±25.0)Ma,表明其形成时代为新元古代。地球化学特征表明该套火山岩形成于岛弧环境,说明当时北祁连东段仍处于洋壳俯冲挤压环境。     

藏南喜马拉雅北坡色龙地区二叠系基性火山岩的发现及其构造意义

藏南喜马拉雅北坡二叠系基性火山岩位于聂拉木县色龙东山。岩石地球化学特征表明,无论是基龙组火山岩还是色龙群火山岩,都具有大陆拉伸-大陆裂谷环境火山岩系的主、微量元素地球化学特征。据此,判断两套基性火山岩的性质和喷发构造环境相同。该区二叠纪大陆拉伸-裂谷火山活动标志着冈瓦纳超级古大陆开始裂离、解体。     

鲁东胶莱盆地青山组火山岩的^40Ar—^39Ar定年——以五莲分岭山火山机构为例

以五莲分岭山火山机构为例，运用高精度的^40Ar－^39Ar定年技术，对胶莱盆地青山组火山岩的形成年龄进行了精确测定。结果表明。青山组第一旋回中偏碱性富钾火山岩的形成年龄为109．9±0．6Ma，第二旋回酸性流纹质火山岩形成年龄为108．2±0．6Ma，据此确定胶莱盆地青山组火山岩应为早白垩世岩浆活动的产物。根据该组火山岩在空间上具有自西向东年龄渐新的演变趋势，表明中生代伊泽奈崎板块向欧亚板块碰撞俯冲应是制约区内火山活动的主要动力因素。