鱼卡煤田大煤沟组高分辨率层序地层特征及聚煤规律

利用高分辨率层序地层学理论和技术方法,综合地震、测井、岩芯和煤质资料对柴达木盆地北缘鱼卡煤田中下侏罗统大煤沟组地层河湖三角洲沉积体系进行高分辨率层序地层学分析,从中识别出短期、中期、长期3个级别的基准面旋回层序,划分出向上"变深"非对称型、向上"变浅"非对称型及对称型3种短期基准面旋回基本结构类型。依据等时地层对比法则进行不同级次基准面旋回层序的联井对比,建立了大煤沟组的等时地层格架,在等时地层格架内进行了煤层对比,并在等时地层格架内分析了聚煤规律。     

西藏驱龙超大型斑岩铜矿床:地质、蚀变与成矿

驱龙超大型矿床是一个产于后碰撞伸展环境下、与大洋俯冲无关的新型斑岩铜矿。文章通过对驱龙铜矿床地质、蚀变与矿化的详细研究,建立了驱龙中新世岩浆演化序列,初步查明了岩浆浅成侵位的构造控制要素,厘定了主要的围岩蚀变类型及空间展布规律,查明了引起各期蚀变事件的地质记录及矿化的空间分布规律,并探讨了成矿物质沉淀的机制,初步建立了该矿床的成矿模型。研究表明,驱龙铜矿中新世斑岩是闪长质深部岩浆房不断演化的产物,花岗闪长岩中新发现的、结晶时间为22.2Ma左右的闪长质包体可近似代表深部岩浆房组分,依次产出的花岗闪长岩、呈岩株或岩枝产出的P斑岩、X斑岩及最晚期的闪长玢岩(15.7±0.2)Ma,均为深部岩浆房连续演化的产物,岩浆持续6Ma左右。岩浆演化过程中角闪石、斜长石不断的结晶分异,导致了岩石常量元素、稀土元素及微量元素组成的规律性变化,斑岩埃达克质的特征也因岩浆演化过程中角闪石等矿物的不断结晶分异而引起。X斑岩中锆石的Hf同位素特征表明,岩石可能形成于新生下地壳的部分熔融。大面积产出的花岗闪长岩为驱龙铜矿最主要的含矿围岩,容纳了驱龙矿床70%以上的矿体,主要由斜长石、钾长石和石英组成,具花岗结构-似斑状结构,近EW向产出,其浅成就位可能受背斜控制,其后的各期斑岩均沿该侵位中心上侵,而冈底斯地壳中新世的快速抬升与剥蚀是导致含矿斑岩浅成侵位的根本原因;矿区内的SN向裂隙带既不控岩,也不控矿。浅成侵位的斑岩及深部岩浆房均发生了流体出溶。发生了大量流体出溶的深部岩浆房,是矿区早期蚀变流体的主要来源,显微晶洞构造及单向固结结构(UST)是流体出溶的地质记录。蚀变主要有3种类型,分别为早期的钾硅酸盐化、青磐岩化以及晚期的长石分解。钾硅酸盐化可分为2个阶段,即蚀变矿物以次生钾长石为主的早期钾硅酸盐化和以次生黑云母为主的晚期钾硅酸盐化。青磐岩化因产出的岩石类型不同,蚀变矿物组合具有明显差异性:产于叶巴组地层中的青磐岩化相对较强,蚀变矿物以绿帘石为主;产于花岗闪长岩中的青磐岩化相对较弱,蚀变矿物以绿泥石为主。晚期长石分解蚀变以破坏长石类矿物为特征,蚀变矿物主要为绢云母-绿泥石-粘土等。石英和硬石膏贯穿于上述各种蚀变中。空间上,钾硅酸盐化位于斑岩体及其周围地区,青磐岩化位于钾硅酸岩化外侧。后期形成的长石分解蚀变强烈叠加了早期钾硅酸盐化,介于钾硅酸盐化带与青磐岩化带之间。与早期钾长石化有关的脉体主要为不规则石英-钾长石脉,与晚期黑云母化有关的脉体主要为不规则至板状的石英-硬石膏脉、黑云母脉,与青磐岩化有关的脉体主要为板状的绿帘石-石英脉,与晚期长石分解蚀变有关的脉体主要为板状黄铜矿-黄铁矿脉及黄铁矿脉;在早期钾硅酸盐蚀变与晚期长石分解蚀变转换阶段,发育一组板状的石英-硫化物脉。早期不规则的脉体形成于斑岩结晶早期、矿区裂隙小规模发育阶段;晚期的板状脉体形成于斑岩弱固结或固结之后、矿区大规模连通裂隙发育阶段。驱龙矿区的铜矿化分布较为均一,主体产于花岗闪长岩中,其中,铜矿化主体形成于黑云母化蚀变阶段,转变阶段及长石分解阶段也有大量铜的形成;钼主要形成于转换阶段,长石分解蚀变阶段也有产出。黑云母化阶段,铜的沉淀与角闪石黑云母化、斜长石钾长石化过程中Ca2 的大量释放有关;转换阶段,铜钼矿化可能与压力和(或)温度骤降有关;晚期铜矿化与长石矿化蚀变阶段,斜长石绿泥石化、黑云母绿帘石化过程中Ca2 及Fe2 的释放有关。     

用随机介质模型方法描述孔洞型油气储层

孔洞型储集层具有强烈的非均质性,在空间分布上变化剧烈,规律性差,其地球物理参数(如速度、密度、弹性参数等)在空间上的变化很难用传统的层状介质模型进行刻画.本文借助随机模型方法,研究孔洞型储层中不同孔洞尺度、分布密度与模型参数的关系,建立反映实际孔洞油气储层介质地球物理参数空间分布统计特征的随机介质模型,以更方便地对孔洞型油气储层进行描述,并为碳酸盐岩孔洞型储层地震反射特征的研究提供有效的方法途径.     

中国南方志留系底部优质烃源岩发育的构造-环境模式

我们对宜昌王家湾和张家界三家馆两个剖面的上奥陶统-下志留统剖面的有机碳丰度、有机碳同位素、以及磷和硫元素进行了测定,并结合区域构造背景分析了有机质生产、聚集、保存的有利条件.研究表明,对于下志留统烃源岩而言,对有机质生产的主要贡献来自光合作用,所生成的有机质聚集在陆缘洼地型活动大陆边缘的分隔性盆地中,其有利保存的缺氧条件与冈瓦纳大陆北缘的区域性的缺氧有关.我们认为,扬子克拉通的志留系底部烃源岩与北非的"hot shale"一样,有很大的勘探前景.     

扬子及周缘地区上奥陶统-下志留统烃源岩发育环境及其控制因素

扬子地区下古生界发育了上奥陶统五峰组和下志留统龙马溪组两套有效烃源岩,查清其发育环境及其控制因素具有重要的科学理论和油气勘探意义.晚奥陶世开始,扬子地区进入碎屑岩陆棚演化阶段;五峰期-龙马溪期,扬子地区主体为局限的深水陆棚环境,总体呈现出浅水陆棚、深水陆棚、次深海共存的古地理格局.沉积体系展布和沉积演化主要受扬子陆块与华夏陆块的汇聚作用控制.扬子地区上奥陶统-下志留统烃源岩的形成与生烃母质生物的高生产力和高埋藏率、冰期-冰后期之交的气温快速转暖、海平面快速上升以及粘土矿物在有机质富集保存过程中的赋存驻留作用等密切相关.     

Application of MODFLOW and geographic information system to groundwater flow simulation in North China Plain, China

MODFLOW is a groundwater modeling program. It can be compiled and remedied according to the practical applications. Because of its structure and fixed data format, MODFLOW can be integrated with Geographic Information Systems (GIS) technology for water resource management. The North China Plain (NCP), which is the politic, economic and cultural center of China, is facing with water resources shortage and water pollution. Groundwater is the main water resource for industrial, agricultural and domestic usage. It is necessary to evaluate the groundwater resources of the NCP as an entire aquifer system. With the development of computer and internet information technology it is also necessary to integrate the groundwater model with the GIS technology. Because the geological and hydrogeological data in the NCP was mainly in MAPGIS format, the powerful function of GIS of disposing of and analyzing spatial data and computer languages such as Visual C and Visual Basic were used to define the relationship between the original data and model data. After analyzing the geological and hydrogeological conditions of the NCP, the groundwater flow numerical simulation modeling was constructed with MODFLOW. On the basis of GIS, a dynamic evaluation system for groundwater resources under the internet circumstance was completed. During the process of constructing the groundwater model, a water budget was analyzed, which showed a negative budget in the NCP. The simulation period was from 1 January 2002 to 31 December 2003. During this period, the total recharge of the groundwater system was 49,374 × 10⁶ m³ and the total discharge was 56,530 × 10⁶ m³ the budget deficit was −7,156 × 10⁶ m³. In this integrated system, the original data including graphs and attribution data could be stored in the database. When the process of evaluating and predicting groundwater flow was started, these data were transformed into files that the core program of MODFLOW could read. The calculated water level and drawdown could be displayed and reviewed online.     

Participation in payments for ecosystem services: Case studies from the Lacandon rainforest, Mexico

Understanding people’s willingness to participate in projects and programmes of payments for ecosystem services (PES) has not been a key analytical concern of the scholarly literature around this new field of environmental policy and practice. This paper analyses participation in four communities benefiting from payments for biodiversity and carbon fixation in Mexico, and contrasts the results for each case with neighbouring communities that do not receive payments. We take a holistic approach that accounts for procedural rules, actors’ interactions, institutions and values, and individuals’ characteristics. We show that the nature of PES rules and the effectiveness of communication with government officers and NGOs influence resource managers’ ability and willingness to participate. We highlight community size, resource managers’ ability to diversify livelihood activities and local perspectives on the conservation of common forests, particularly sacred values and intergenerational concerns on forest conservation, as critical participation drivers. This analysis provides insights on why and how these new institutions may be attractive for some resource managers and permits to draw some recommendations for the future design of PES projects and programmes.     

Modeling households’ decisions on reconstruction of houses damaged by earthquakes––Japanese case study

In this study, households’ decisions on reconstruction of damaged houses were modeled, using questionnaire data in Japan. Characteristics of households’ decisions were investigated using parameter estimation results. The effects of subsidizing policy were evaluated as follows. First, subsidy for rebuilding may be effective for the households whose houses were heavily damaged. Second, there is a possibility that subsidy accelerated rebuilding of houses by the households having children. Third, subsidy for rebuilding may not be effective for elderly people’s households and households in depopulated areas.     

Flood hazard delineation combining geomorphological and hydrological methods: an example in the Northern Iberian Peninsula

Flood mapping requires the combination and integration of geomorphological and hydrological-hydraulic methods; however, despite this, there is very little scientific literature that compares and validates both methods. Two types of analysis are addressed in the present article. On the one hand, maps of flood plains have been elaborated using geomorphological evidence and historical flood data in the mountainous area of northwestern Spain, covering an area of more then 232 km² of floodplains. On the other hand, a hydrometeorological model has been developed (Clark semidistributed unit hydrograph) in the Sarria River basin (155 km², NW Spain). This basin is not gauged, hence the model was subjected to a goodness-of-fit test of its parameter (curve number) by means of Monte Carlo simulation. The peak flows obtained by means of the hydrological model were used for hydraulic modeling (one-phase, one-dimensional and steady flow) in a 4 km² urban stretch of the river bed. The delineation of surface areas affected by floods since 1918, as well as those analyzed subsequent to the geomorphological study, reveals a high degree of reliability in the delineation of the flooded areas with frequent recurrence intervals (<50 years). If we compare these flooded surface areas with the estimate obtained by the hydrological-hydraulic method we can see that the latter method overestimates the extent of the surface water by 144% for very frequent recurrence intervals (>10 years) and underestimates it as the recurrence interval increases, by up to 80% less floodplain for exceptional events (>500 years). Finally, a management map is put forth combining the most reliable results available by integrating both methods. Originally presented at the Sixth International Conference on Geomorphology.