黄土塬区地震勘探技术发展现状综述

黄土塬区的地震勘探技术长期以来一直被认为”世界级”难题,其主要原因有三：一是黄土塬区复杂的地貌条件,即沟、梁、塬、峁、坡、川并存;二是复杂的地表条件,即沟壑纵横施工困难;三是复杂的表浅层条件,即地震波难以激发且能量衰减严重等。在具体分析我国黄土塬区资源分布状况与勘探实践的基础上．对黄土塬区地震勘探数据采集与资料处理的一些技术难点进行了阐述,指出今后在黄土塬区开展地震勘探工作,应从粘弹介质、连续介质的角度．进行地震波激发与传播规律的研究,从地震正演模型和室内模拟的角度,进行黄土塬区的资料采集和处理方法研究,同时要注重引进新技术,加强储层物性横向变化的预测研究。     

大比例尺化探工作中异常评序的指标选择

本文分析了异常评序的常用指标、方法,应用实例对不同指标组合的评序结果进行了对比分析。对于1∶1万大比例尺化探异常评序提出:分区块采用纯地球化学指标对主成矿元素异常进行评续即可;地球化学指标的选用不是越多越好,采用四指标(面积、最大值、平均值、变异系数)方法简便、评序结果客观准确,可以有效甄别矿致异常。     

降雨条件下边坡有限元强度折减法计算平台开发及其应用

降雨是导致边坡失稳的主要因素。目前,使用有限元强度折减法进行降雨滑坡计算时,过程比较复杂,计算工作量大。同时,对降雨边界的处理更加大了计算的复杂性,从而影响了强度折减法在降雨滑坡计算中的推广应用。为了更加准确、高效地将有限元强度折减法应用于降雨滑坡计算,首先基于Geostudio软件采用迭代算法对降雨入渗边界进行处理,通过计算得到每一时刻边坡内的水压分布,然后利用Fortran编制程序将水压转化为等效结点力并导入ABAQUS中,之后结合“基于场变量的有限元强度折减法”对ABAQUS进行二次开发,最终建立降雨条件下边坡有限元强度折减法计算平台。该平台利用Geostudio考虑了降雨入渗边界的复杂性,克服了ABAQUS软件中不能准确模拟降雨边界的问题。同时采用ABAQUS软件提供的场变量,对有限元强度折减法的计算过程进行简化,提高了计算效率,经过一次计算即可求得每一降雨时刻的边坡稳定系数。通过与传统极限平衡法进行比较,发现两者得出的结果具有较好的一致性,表明该计算平台是稳定、可靠的。最后采用该平台对降雨滑坡机理进行研究,研究结果可为边坡防减灾提供参考。     

黄骅坳陷石炭-二叠系凝析油气地球化学特征及来源分析

深层油气勘探是未来油气资源的重要接替领域。渤海湾盆地下伏石炭-二叠系煤系烃源岩自油气勘探取得新突破以来,一直是深层油气领域研究的热点。黄骅坳陷新部署的QG8井奥陶系碳酸盐岩储层和YG1井二叠系砂岩储层获高产凝析油气流,其来源判别问题是深层油气勘探的关键。针对QG8、YG1井凝析油气开展的生物标志化合物、有机碳稳定同位素和原油物性研究表明：两口井的凝析油均为低黏度、低密度的典型轻质原油,具有姥鲛烷优势（Pr/Ph>2.8）,QG8井凝析油饱和烃δ¹³C为-29.1‰、芳烃δ¹³C为-26.8‰;天然气δ¹³C₁偏重,介于-39.7‰~-36.4‰之间,干燥系数大于0.8,重烃可达16.2%,为偏干湿气。QG8与YG1井凝析油特征与黄骅坳陷石炭-二叠系煤系烃源岩（饱和烃δ¹³C为-29.26‰~-26.87‰,芳烃δ¹³C为-26.62‰~-24.15‰）及KG4井原油物性（0.757 1~0.840 2 g/cm³）相近,天然气特征则相似于济阳坳陷GBG1井的煤成气（δ¹³C₁为-43‰~-35‰）,表明高产的凝析油气来自石炭-二叠系煤系烃源岩。证实渤海湾盆地深层石炭-二叠系煤系具有生烃潜力和油气勘探前景。     

东布什维尔德杂岩下部和下部临界带铂族元素丰度

1 绪言本文报道的是出露在 Clapham 118 KT农场下部带和临界带岩系的铂族元素分析结果。该处总的地质情况基本相似,但岩层厚度不大,含橄榄石比率各有不同,虽临界带产出有铬铁矿,但斯蒂尔波特(Steelpoort)铬铁岩层之下无分散铬铁岩出现。其地质柱状剖面示于     

Astronomical identification of the C3H radical

The C3H radical, a linear carbon chain with a 2 pi electronic ground state, has been identified in the millimeter-wave spectra of two astronomical sources, IRC +10216 and TMC-1, and conclusively confirmed (accompanying Letter) in a laboratory glow discharge. In IRC +10216 four rotational transitions have been observed, three in the lower fine-structure ladder (2 pi 1/2) and one in the upper (2 pi 3/2), each a resolved or partially resolved lambda-doublet. In TMC-1, both lambda components of the lowest lying 3/2 --> 1/2 transition of the 2 pi 1/2 ladder have been observed, each with well-resolved hfs. In IRC +10216 the excitation of C3H is similar to that of SiCC: the rotational temperature Trot within the 2 pi 1/2 ladder is low (8.5 K), owing to rapid radiative decay, while Trot across the ladders is high (approximately 52 K) because interconnecting far-IR radiative transitions are only weakly permitted. The column density of C3H in IRC +10216 averaged over the estimated source diameter of 84" is 2.8 x 10(13) cm-2, an order of magnitude less than that of C2H and C4H. A determination of the spectroscopic constraints of C3H that permitted the entire radio spectrum of this molecule to be calculated to high accuracy has been derived from analysis of the combined astronomical and laboratory data presented in the accompanying Letter.     

Cellular diagnostics and coral health: declining coral health in the Florida Keys

Coral reefs within the Florida Keys are disappearing at an alarming rate. Coral cover in the Florida Keys National Marine Sanctuary declined by 38% from 1996 to 2000. In 2000, populations of Montastraea annularis at four sites near Molasses Reef within the Florida Keys National Marine Sanctuary and one reef within Biscayne National Park were sampled on a quarterly basis. Anecdotal observations showed corals at Alina's Reef in Biscayne National Park appeared healthy in March, but experienced an acute loss of coral cover by August. Cellular Diagnostic analysis indicated that Alina's Reef corals were in distress: they had been afflicted with a severe oxidative damaging and protein-denaturing stress that affected both the corals and their symbiotic zooxanthellae. This condition was associated with a significant xenobiotic detoxification response in both species, reflecting probable chemical contaminant exposure. These results demonstrate that applying a Cellular Diagnostic approach can be effective in helping to identify stress and its underlying causes, providing diagnostic and prognostic biomarkers of coral health.     

Implications of ground water chemistry and flow patterns for earthquake studies

Ground water can facilitate earthquake development and respond physically and chemically to tectonism. Thus, an understanding of ground water circulation in seismically active regions is important for earthquake prediction. To investigate the roles of ground water in the development and prediction of earthquakes, geological and hydrogeological monitoring was conducted in a seismogenic area in the Yanhuai Basin, China. This study used isotopic and hydrogeochemical methods to characterize ground water samples from six hot springs and two cold springs. The hydrochemical data and associated geological and geophysical data were used to identify possible relations between ground water circulation and seismically active structural features. The data for delta18O, deltaD, tritium, and 14C indicate ground water from hot springs is of meteoric origin with subsurface residence times of 50 to 30,320 years. The reservoir temperature and circulation depths of the hot ground water are 57 degrees C to 160 degrees C and 1600 to 5000 m, respectively, as estimated by quartz and chalcedony geothermometers and the geothermal gradient. Various possible origins of noble gases dissolved in the ground water also were evaluated, indicating mantle and deep crust sources consistent with tectonically active segments. A hard intercalated stratum, where small to moderate earthquakes frequently originate, is present between a deep (10 to 20 km), high-electrical conductivity layer and the zone of active ground water circulation. The ground water anomalies are closely related to the structural peculiarity of each monitoring point. These results could have implications for ground water and seismic studies in other seismogenic areas.     

Characterizing aquatic sediment-oil aggregates using in situ instruments

The effects of emulsified crude oil and salinity (15, 30 per thousand ) on the steady state aggregate volume distributions and fractal dimensions were determined for a range of mean velocity gradients, (G(m) =5-50 s(-1)). Aggregation was performed in a 40-L cylindrical tank with a 4-blade paddle mixer. Three-dimensional fractal dimensions (D3) and volume distributions were determined using a procedure integrating data from an electrozone and an in situ light scattering instrument. Two-dimensional fractal dimensions (D2) and derived volume distributions were determined using a recently developed submersible flow cytometer equipped with a digital camera and image analysis software. For latex beads or emulsified crude oil systems, the above listed instruments yielded consistent size distributions and fractal dimensions (D2=1.92 +/- 0.16, D3=2.94 +/- 0.12). Mean volume aggregate diameters determined using the FlowCAM were consistently larger that those determined using the LISST-100 or Coulter Multisizer due to aggregate orientations during measurements. With increasing G(m) values, all colloidal aggregates showed increasing D3 values due to reduced aggregate length. Because of the compactness of all the aggregates (D3 >2), D2 values remained constant at 2. Neither salinity nor sediment type significantly affected D2 values calculated for sediment-crude oil aggregates. However, clay-oil aggregates showed higher D3 values than clay aggregates. This suggests that colloidal oil and mixing shear are the more dominant factors influencing aggregate morphology in nearshore waters. Overall, the data suggests that the analysis methods provide consistent size distribution results. However, because of the shear and salinity of coastal waters, resulting aggregates are too compact to estimate their D3 values using image analysis alone.     

氮与磷的增加对海水无机碳体系影响的实验模拟研究

海洋碳循环是全球变化研究中的重要领域,它不仅在很大程度上决定了全球气温乃至全球气候的变化趋势,而且还是海洋生态系持续发展的基础,它决定着了海洋生态环境变化的走向。众所周知,碳(C)在海洋中以无机态和有机态的形式存在,在海-气系统中,大于98%的C以溶解无机碳(DIC)形式存