冀中文安斜坡石炭—二叠纪煤系特征及岩浆热力成烃作用

对文安斜坡石炭—二叠纪(C—P)煤系特征,尤其是煤的煤岩显微组分组成和煤及煤的各显微组分的元素组成特征的研究表明,本区煤中镜质组含量占绝对优势且较富氢。本文还研究了新生代该煤系的再次埋藏和该区下第三系岩浆活动以及煤系中多层辉绿岩侵入的热力作用对其成熟度的各自影响程度,认为本区已发现的煤成油气藏大体分布在平均R_0为1.0％～2.0％的苏桥地区,与早第三纪岩浆活动有密切关系。岩浆热力影响有效地促进了煤系烃源岩的热演化和成烃转化,而破坏作用则不大。     

Chi-square tests for markov chain analysis

Markov chain analysis has become a popular and useful technique for the evaluation of stratigraphic information. Field data on frequencies of facies transitions are first assembled in a transition count matrix. Observed frequencies can be compared statistically with frequencies expected if no order, or memory, exists in the stratigraphic sequence. Two chi-square (²) tests have been proposed for this purpose. One of the previously proposed ² tests was observed to give anomalously large values of the test statistic during another study. This unsatisfactory behavior is verified here. Limiting values of the two ² tests (from tables) are compared with the distribution of values for both test statistics obtained by analyzing many random matrices generated by a simple computer program. In all cases, the logarithmic ² test, suggested by several previous authors, fails to provide any meaningful assessment of the presence or absence of order in stratigraphic sequences evaluated. Further use of this test should therefore be avoided.     

The gross features of the lithosphere-asthenosphere system in Europe from seismic surface waves and body waves

Long-period recordings of dispersive Rayleigh waves along numerous station lines, or profiles, in Europe have for the first time permitted a uniform inversion of these observations based on a new method of phase velocity regionalization.Regional dispersion relations obtained by this method have then been subjected to a complete inversion procedure commonly known as the hedgehog method. The results are presented in a map outlining the thickness of the lower lithosphere (lid) and the shear (S) velocities in both the lid and the asthenosphere channel.A comparison of these results with the minimum compressional (P) wave velocities in the asthenosphere and their corresponding depths provides an estimate of theV _p /V _s ratio for the asthenosphere in the European area.Contribution No. 314, Institute of Geophysics, ETH-Zürich, Switzerland.     

New latest Cretaceous microvertebrate fossil assemblages from the Haţeg Basin (Romania)

Late Cretaceous terrestrial ecosystems in southern Europe are relatively poorly known, although much progress has been made during the past decade, principally with regard to the microvertebrate components of these ecosystems. The Maastrichtian terrestrial deposits of the Haeg Basin, at the easternmost end of the South European archipelago and well known for reptilian fossils (e.g., turtles, crocodilians, pterosaurs and dinosaurs), have been thoroughly screened during the past five years. Important microvertebrate assemblages, both quantitatively and qualitatively speaking, were found at Pui (Sînpetru Formation), Tutea and, particularly, Vlioara (Densu-Ciula Formation). Several new taxa are noted here for the first time for the Haeg Basin, including gars, discoglossids, albanerpetontids, scincomorphan and anguimorphan lizards; dromaeosaurids and multituberculates are confirmed. Most of the microvertebrate remains are poorly preserved and precise systematic assignment has proved difficult. The Haeg fauna appears to be primitive and endemic, with a Neopangean core composition, and suggests a composite palaeobiogeographic origin for the Late Cretaceous European ecosystems, confirming conclusions reached in studies of the larger vertebrates.     

Oxidation and Origin of Organic Matter in Surficial Eastern Mediterranean Hemipelagic Sediments

Aerobic mineralisation of C_org in surface sedimentsof the deep (>2000 m water depth) eastern Mediterranean Sea has been quantified by analysis of detailedbox core C_org concentration versus depth profiles and the modelling environment for early diageneticproblems MEDIA. The reactive fraction comprises 60–80% of the total C_org reachingthe sediments and is largely oxidised within the surficial 10 cm. A non-reactive C _orgfraction (G_NR) dominates at depths >10 cm, and makes up20–40% of the total C _org flux to the sediments. First-order rateconstants for decomposition of the reactive fraction calculated from theC _org profiles range from 5.4 × 10^-3 to8.0 × 10^-3 y^-1 to 8.0 × 10^-3 y^-1. Total mineralization rates in thesurface sediment are between 1.7 and 2.6 mol C cm^-2 y^-1 and thus are typical for oligotrophic, deep-seaenvironments. The low fluxes and rapid remineralisation of C _org are accompanied by²¹⁰Pb_excess surface mixed layers which are only 2 cm deep, among the thinnest reported for oxygenated marine sediments.Model results indicate a mismatch between the C _org profiles and O₂ microprofileswhich were measured onboard ship. This can be attributed to a combination of decompression artefactsaffecting onboard measurement of the O₂ profiles or the leakage ofoxygen into the core during handling on deck. Furthermore, the used D_b values, based on ²¹⁰Pb, may not befully appropriate; calculations with higher D_b values improve the O₂ fits. The surficial sediment¹³C _org values of -22 become less negative with increasing depth and decreasing C _orgconcentrations. The major ¹³C change occurs in the top 3 to 4 cm and coincides with the interval weremost of the organic carbon oxidation takes place. This indicates that the reactive fractionof organic matter, commonly assumed to be marine, has a more negative ¹³C _orgthan the refractory fraction, usually held to be terrestrial. Palaeoproductivity estimates calculated from thesediment data by means of literature algorithms yield low surface productivities(12–88 gC m^-2 y^-1), which are in good agreement with field measurements of primary productivity in otherstudies. Such values are, however, significantly lower than those indicated by recent productivitymaps of the area derived from satellite imagery (>100 gC m^-2 y^-1).     

丽江7.0级地震地表破裂与形变特征

丽江７．０级地震序列发生在该地区属次级构造的断裂上，而且这次地震的烈度分布，地表破坏分布和强余震分布都表现了异常不均匀性。根据大震震害损失评估调查和大震现场地面破坏调查取得的资料，对上述异常现象的原因进行了初步分析，认为主震发震构造为玉龙山山前近南北向断裂，但其破裂过程可能存在“跳跃”和偏转。     

丽江7.0级地震前后滇西实验场的重力异常变化特征

１９９６年２月３日，在云南省西北部的丽江县境内发生了一次Ｍｓ７．０级强烈地震。此次地震前后滇西实验场重力网共进行２７期流动重力观测，其重力变化的总体特征为：１．震中附近地区的丽江－剑川－洱源－带震前为下降变化，下降变化的幅值平均约３０×１０＾－８ｍｓ＾－２左右，震后重力变化继续下降；２．距震中稍远一点的渡口附近地区震前为持续上升变大，累计上升变化的最大幅值达１２３×＾－８ｍｓ＾－２，震后重力变化下     

丽江7.0级地震土木结构房屋破坏比和损失比

本根据丽江地震区１１３个自然村震害调查资料，对不同烈度区土木房屋不同破坏等级破坏比的分布特点进行了初步研究，对破坏比与烈度的关系进行了统计分析，并给出了相应的统计关系，另外，通过实地调查，给出了本次地震土木结构房屋不同破坏等级的损失比。     

滇西澜沧变质带中白云母b_0值特征及其多期变质作用意义

滇西澜沧变质带中199件白云母b_0值分析结果表明,b_0值均在0.9020nm以上。与澜沧变质带遭受蓝片岩相高压变质作用的事实相吻合。此外,白云母b_0值的统计规律显示,澜沧变质带经历了多期变质作用,一期为高压变质作用,另一期为中压变质作用,这也与已知的地质现象相符。由此可见,白云母b_0值可以很好地反映多期变质作用。     

川西滇东地区前寒武系地层中白云母b0值的初步研究

在川西滇东地区的前寒武系变泥质岩地层中采了263个样品并测了其白云母b₀值,结果表明:渡口运动时发生低压高温的变质作用;川滇运动时在河口组及相应地层发育区发生中压变质作用,向两侧变质压力降低;晋宁运动挤压幕第Ⅰ期形变时发生低压变质作用,第Ⅱ期形变时发生中-高压变质作用,第Ⅲ期形变和澄江运动时发生中压变质作用。基于这一工作探讨了白云母b₀值研究在进行地层对比和构造分析中的积极作用。