致密砂岩衰减岩石物理图板分析:储层微裂隙预测

致密砂岩储层普遍具有孔隙度低、微裂隙发育的特点,岩石内部常含有强烈的结构非均质性.致密砂岩发育的微裂隙使储层具有良好的连通性,促成高饱和气的天然气成藏.针对川西某探区须家河组高含气饱和度致密砂岩,本文选取致密砂岩岩心样本,进行了不同围压下的超声波实验测量.考虑储层完全饱气情况下的粒间孔隙、微裂隙双重孔隙结构,采用Biot-Rayleigh双重孔隙方程,构建致密砂岩岩石物理模型,进而分析了裂隙含量对纵波频散和衰减的影响.基于地震波衰减,构建了致密砂岩多尺度岩石物理图板.采用谱比法和改进频移法估算致密砂岩样本及储层衰减,对超声和地震频带下的图板进行校正.将校正后的图板应用到研究工区,选取二维测线和三维区块,进行储层孔隙度和裂隙含量的定量预测.对比实际资料进行分析,结果显示,本文预测的孔隙度和裂隙含量与三口测井的孔隙度曲线和实际产气情况基本吻合,基于孔隙-裂隙衰减岩石物理模型有效地预测了优质储层的分布区域.     

蒂明斯地区含金铁建造的痕量元素和稳定同位素地球化学

一、作者对蒂明斯南部迪洛罗群火山岩含金与不含金的燧石——磁铁矿铁建造的痕量元素和稳定同位素特征进行了对比,目的在于:1)确定这一环境内金的勘探准则:2)描述金矿化和碳酸盐蚀变的热液史。含金铁建造富含金、硫、钨、锑和二氧化碳。含金和不含金的两种铁建造具有相似的砷丰度。铁建造中的金表现为两种形式:1)原生金和保存在变质石英脉的黄铁矿里的包裹金;2)广泛分布在铁建造中的,与变质石英脉在空间上不共生的黄铁矿和磁黄铁矿颗粒中包裹的金。含金铁建造和在低温条件下被海水蚀变的玄武岩含有交代方解石,其δ13C 同位素组成为-1～-2‰(POB)。浸染状碳酸盐化蚀变带边部的方解石和核心部分的白云石.其δ13C 组成分别为-2‰和-4‰。这种趋势同蚀变带中心较高温碳酸盐沉淀物相一致。铁建造中交代碳酸盐的δ13C 组成范围从-2‰～-5‰.与磁铁矿的丰度有关。同生燧石碎屑和交代碳酸盐同遍在的含氧变质孔隙溶液有氧的交换。     

起源于前寒武纪的碳氢化合物

1965至1975年间,在包括南极在内的世界各地,陆续发表了一些据认为是前寒武时代的化石或有机物的报告,这些化石可能属起源于前寒武纪的碳氢化合物这一问题,除苏联学者外,没有引起更多人的注意。     

塞拉利昂太古宙基底中不一致的Rb—Sr和Pb—Pb全岩等时年龄的意义

英国地质科学研究所一个研究队(I.G.S),通过对塞拉利昂北部的野外制图和构造研究,建立了西非克拉通太古宙地层层序,划分出一个较老的利欧尼亚(Leonian)花岗岩—绿岩区,它在利比里亚构造—变质事件结束时形成的,一个花岗岩—绿岩区之前就经受过一次构造—变质事件。在法杜古区,在具有利欧尼亚构造的花岗片麻岩中,得到在统计学上是合理的但不一致的Pb—Pb和Rb—Sr全岩等时年龄分别为2959±50百万年和2753±61百万年(误差2σ)。这些年龄是和塞拉利昂其他地区的利欧尼亚和利比里亚构造放射年龄可对比,可以认为,法杜古区的Rb—Sr全岩等时年龄已受到利比里亚事件的影响。法杜古片麻岩的Pb—Pb全岩等时年龄和一个先前测定的(经重新计算并作部分检查)取自塞拉利昂东南花岗片麻岩中的Rb—Sr全岩等时年龄为2980±80百万年,为利欧尼亚构造—变质事件提供了一个确切的年龄,约2970百万年。利欧尼亚花岗岩类的。~(87)Sr/~(86)Sr初始值和现代单阶段模式U~(238)/Pb~(204)值很难与地幔的值相区分,但并不排除这种可能性,即这些花岗岩类是来自地壳或下部地壳只经历了一个短暂时期的那些母质中。法杜古区花岗片麻岩的2753±61百万年的Rb—Sr全岩等时年龄为塞拉利昂北部的利比里亚事件提供了一个确切的年龄。在野外划分出比利欧尼亚更老的(即老于2970百万年)一套岩石,但还没有测定同位素年龄。     

地质省在前寒武纪古地磁研究中的作用

按地质省编辑了北美和欧洲波罗的海地区14亿年前的前寒武纪岩石A类古地磁资料。目的是试图建立各个构造省的极移曲线,以便检验加拿大和费诺—萨尔马提地盾的克拉通内部完整性。根据这种见解,由于资料贫乏,对大多数省来说,不可能得出任何结论。有可能提出若干试验性的意见,供以后检验: (1)单条极移曲线满足可利用的北美24亿年前的资料。 (2)从距今22亿年到18亿年,在苏必利尔省(十南方省和怀俄明省)和邱吉尔省(十斯拉夫省和拉布多省)之间形成威尔逊环。 (3)单条极移曲线满足了怀俄明省和苏必利尔省的资料。 (4)就每个省来说,有些资料不易适合任一简单极移曲线型式。     

西澳大利亚金色丛林铜矿床的硫同位素和矿石成因的初步研究

由块状黄铜矿—磁铁矿透镜体组成的太古代层状金色丛林(Golden Grove)矿床的δ~(34)S_(CDT)值范围从-1.4per mil到 4.4 permil(平均 1.0 permid。类似的分布也来自矿化层(范围-2.5到 4.0,平均 0.9)和富Zn的上盘燧石层(范围-0.1到4.3,平均 1.6)浸染状的硫化物中。由于沉淀和成岩的影响,在共生的硫化物系统中同位素具不平衡性,通过绿片岩相变质作用而保存下来。对于地层最高的铜透镜体平均δ~(34)S值中两个per mil的减损说明当硫化物沉积时,在矿液中向高fo_2的临时变化。这些资料证实了海底硫化物的堆积模式是在活动构造环境中发生间隙性喷发作用的结果。说明岩浆(少年期)硫是矿液中硫的主要来源。     

Distribution and characteristics of suspended particulate matter in a heavily eutrophic estuary, Tokyo Bay, Japan

Bulk suspended particulate matter (SPM), chlorophyll a (Chl a), ignition loss, particulate organic carbon (POC), organic nitrogen, inorganic phosphorus (PIP), and organic phosphorus were investigated in the heavily eutrophic Arakawa River estuary, Japan. Chl a was high (approximately 35 microg l(-1)) in summer and low (approximately 6.7 microg l(-1)) in winter and autumn. POC from living phytoplankton accounted for approximately 34% and approximately 70% of total POC during low- and high-biomass seasons, respectively. During the low-biomass season, detrital POC distribution was conservative, and less reactive, land-derived materials mainly composed particulate organic materials (POM), but complex mixing of land-derived POM and autochthonous planktonic detritus caused nonconservative detrital POC behavior during the high-biomass season. PIP concentration in SPM decreased with increasing salinity, likely by desorption of soluble orthophosphate (ortho-P). The ortho-P released from SPM, 56% of the ortho-P input from the Arakawa River to the bay, was a significant potential source of biologically available phosphorus causing eutrophication of coastal environments.     

Evidence of chromosomal damage in common eiders (Somateria mollissima) from the Baltic Sea

Common eiders nesting in the Baltic Sea are exposed to generally high levels of contaminants including potentially genotoxic polycyclic aromatic hydrocarbons and organochlorines. Blood samples were collected from eiders at eight sites in the Baltic Sea and two sites in the Beaufort Sea. DNA content variation was estimated using the flow cytometric method, and subsequently utilized as a biomarker of genetic damage. We observed no significant differences in genetic damage among populations within either the Baltic or Beaufort Seas. However, eider populations from the Baltic Sea had significantly elevated estimates of genetic damage compared to populations from the Beaufort Sea.     

Seasonal variations of physiological and cellular biomarkers and their use in the biomonitoring of north Adriatic coastal waters (Croatia)

Lysosomal membrane stability, the content of neutral lipids and lipofuscin as cellular biomarkers were measured in the digestive gland of mussels, Mytilus galloprovincialis Lam., during a one year survey at selected sites along the coast of the northern Adriatic. The ability of mussels to survive in air as a general physiological response was tested at the same sites. Annual changes of sea temperature, salinity, O(2) saturation, pH and chlorophyll a concentration were measured and the effects of these environmental factors on the biomarkers selected for this study were determined. Survival of mussels after aerial exposure was significantly (p < 0.05) reduced in mussels collected from the contaminated harbors of Pula and Rijeka compared to clean control sites. Lysosomal membrane stability of mussels from urban and industrial areas was also lower indicating exposure to different environmental contaminants. At the same sites, the content of neutral lipids and lipofuscin in digestive cells was significantly higher compared to the reference sites, suggesting alterations in lipid metabolism and contaminant-induced peroxidation of cell membranes. The greatest influence of natural environmental factors was observed for the aerial survival of mussels and the neutral lipids and lipofuscin content in the digestive gland, indicating that the annual cycles of biomarker responses should be well understood for a correct interpretation of biomonitoring results.     

Microbiological Indices for total coliform and E. coli bacteria in estuarine waters

Bacterial counts for total coliforms and E. coli in estuaries are normally orders of magnitude greater at the freshwater end than at the seaward end and tidal movements and variations in freshwater flows produce continual change in the freshwater/seawater mix--this causes the bacterial counts to vary greatly throughout the estuary and the complexity creates difficulty in appraising or assessing the bacterial counts (i.e. difficulties arise when deciding if the bacterial counts for estuarine water samples are within an acceptable range--relative to their corresponding salinities). The situation is further complicated in estuaries where sewage is discharged directly. Microbiological criteria and indices that can be used in a practical way to overcome these difficulties were developed. The procedure is summarised as follows: 1. Primary criteria are proposed for total coliform and for E. coli bacteria in the freshwater at the head of the estuary and in full seawater at the mouth of the estuary. 2. For estuarine or transitional waters (i.e. waters with salinity ranging from 0 per thousand to 35 per thousand), distinct criteria are calculated for each individual sample--with a separate criterion for total coliforms and for E. coli--the individual criteria are founded on the primary criteria and vary with salinity on a pro-rata or linear basis. 3. Finally, the Microbiological Index for each result is obtained by dividing the actual bacterial count by the corresponding criterion--the acceptable Index is then equal to 1--at any salinity (i.e. where the Index is <1 then the bacterial count complies with the criterion, and where the Index is >1 then the count breaches the criterion). The Index also indicates the extent of the compliance or non-compliance with the corresponding criteria. An example of the application of the Microbiological Index is also presented--including examples of graphs that demonstrate how microbiological data for estuarine waters can be summarised and presented.