准噶尔盆地西北缘及玛湖凹陷沉积储集层研究进展*

准噶尔盆地西北缘玛湖凹陷中心区10×10⁸ t级砾岩大油区的发现,带动了该区沉积储集层研究的不断深入。作者梳理了准噶尔盆地西北缘及玛湖凹陷的沉积储集层研究现状和进展,认为准噶尔盆地西北缘及玛湖凹陷的沉积储集层研究的进展主要表现为: (1)提出了新的砂砾岩储集层岩石相和岩石学分析方法;(2)探索形成了新的沉积储集层地球物理测井和地震描述技术;(3)针对不同层系,在沉积物源、沉积相、沉积环境、沉积体系和沉积模式等方面取得大量新认识,建立了大型退覆式浅水缓坡扇三角洲沉积模式,指导油气勘探不断获得新突破;(4)在成岩作用理论指导下,所发现的储集层埋藏深度不断增加。研究表明,玛湖凹陷的沉积体系具有继承性: 从二叠纪到新近纪,发育了火山—碎屑岩沉积体系、细粒—蒸发盐沉积体系以及粗粒冲积扇、扇三角洲、辫状河三角洲等沉积体系,气候、构造和湖平面变化控制了沉积体系的形成和演化。沉积储集层研究为玛湖砾岩大油田的发现提供了有力的理论支持。未来应当加强针对古老层系和深部地层的沉积储集层研究工作,重视新理论新技术在西北缘和玛湖沉积储集层研究中的应用,已经形成的理论技术需要在勘探实践中接受进一步检验和完善。     

隆林县石漠化地区发展金银花种植气候适应性分析

以隆林县石漠化地区的气候条件为依据,采用比较分析方法,对金银花的气候生态规律和环境因子对金银花生长、产量的影响进行分析,找出其影响的气候指标。结果表明,隆林县石漠化地区金银花生长条件较好,西北部山区和南部高寒山区为适宜区,其它区域仅为次适宜区,为石漠化地区发展金银花种植提供气候依据。     

湖南省柿竹园矽卡岩矿床中石榴石特征

通过野外与显微镜观察和电子探针分析, 对柿竹园多金属矿床矽卡岩中石榴石的特征进行了研究.根据石榴石的产出状态、矿物的共生组合, 矽卡岩可分为4个带: 磁铁矿-辉石-石榴石带、辉石-石榴石带、符山石-石榴石带、矽卡岩化大理岩带.从成分上的变化, 探讨了石榴石在各矽卡岩带中的特征.柿竹园矿床矽卡岩中的石榴石可分为早、晚两期, 早期形成的石榴石颜色为暗棕色, 并且在垂直和水平方向上有明显的变化规律.从磁铁矿-辉石-石榴石带到矽卡岩化大理石带, 随着石榴石中Fe₂O₃含量的减少, Al₂O₃含量的增加, 由钙铁榴石向钙铝榴石变化; 石榴石晶体具有从核部向边缘由均质性向非均质性变化的规律.早期石榴石形成于较氧化的条件下, 温度为520~620℃, 压力为1000×105Pa, 由富含Si, Al, Fe, Cl, F组分的热液和泥盆纪佘田桥组灰岩反应交代形成.当温度降至450~ 540℃, pH, Eh值降低时, 晚期石榴石形成的同时使白钨矿沉淀.晚期石榴石颜色比早期形成的石榴石浅, 为红色.结晶颗粒较大, 并且, 普遍可以观察到石榴石环带结构.      

A multiscale work-analysis approach for geotechnical structures

This paper presents a second-order work analysis in application to geotechnical problems by using a novel effective multiscale approach. To abandon complicated equations involved in conventional phenomenological models, this multiscale approach employs a micromechanically-based formulation, in which only four parameters are involved. The multiscale approach makes it possible a coupling of the finite element method (FEM) and the micromechanically-based model. The FEM is used to solve the boundary value problem (BVP) while the micromechanically-based model is utilized at the Gauss point of the FEM. Then, the multiscale approach is used to simulate a three-dimensional triaxial test and a plain-strain footing. On the basis of the simulations, material instabilities are analyzed at both mesoscale and global scale. The second-order work criterion is then used to analyze the numerical results. It opens a road to interpret and understand the micromechanisms hiding behind the occurrence of failure in geotechnical issues.     

Correction of common lead in U-Pb analyses that do not report 204 Pb

During the Early-Middle Proterozoic era, three major lithostratigraphic unit associations, namely Hekou-Dahongshan, Dongchuan, and Kunyang-Huili Groups, were established for the metamorphosed volcanic-sedimentary rocks exposed in the southwestern Yangtze Block (SWYB). The integration of petrology, geochemistry and geochronology constrains tectonic framework and evolution of the SWYB, in which four sets of SHRIMP U-Pb zircon ages were obtained from the volcanic rocks interbedded within the Middle Proterozoic successions: 1800–1600 Ma, 1600–1300 Ma, 1300–1100 Ma, and 1100–1000 Ma. Major and trace elemental analysis indicate that four key tectonic evolutionary stages, each coinciding with the above radiometric age set, of the SWYB during the Early-Middle Mesoproterozoic. The SWYB was characterized by an east-westerly trending rift in the Hekou, Dongshan, and Dongchuan areas, and separate basin-forming events during 1800–1600 Ma and 1600–1300 Ma, respectively. In the SWYB, an intracontinental rift basin and a rift basin occurred in the Caiziyuan-Matang and Laowushan areas, respectively in 1300–1100 Ma ago. During 1100–1000 Ma, the SWYB was characterized by the closure of the Caiziyuan-Matang rift-ocean basin, collision between the Huili Blocks and Kunyang Blocks, and presence of volcanic arcs in the Tianbaoshan and Fulingpen areas. Accordingly, the SWYB represents a new basin that records the relatively complete assembly process of the Rodina during the Early-Middle Mesoproterozoic era.     

地史转折期的生态系

生态系的演变是地球各圈层系统耦合关系变化的直接标志。地史转折期的生态系具有复杂的生物内涵，在绝灭—残存—复苏过程中，各生物类别的演替遵循着一定的生存型式。大绝灭后生态系复苏的原动力是绝灭后迁入避难所的复活类型和大绝灭末期高压环境中产生的祖先类型的新生和辐射发展。全面了解绝灭后生态系的组成和结构，对于正确认识地史转折期，即圈层耦合结点处的地质作用型式和过程具有重要作用。     

Storm Deposits of the Sinian Zhangqu Formation in Northern Anhui — An Upward Shallowing Carbonate Sequence1

Abstract This paper studies, for the first time, the storm deposits of a carbonate sequence in the Sinian Zhangqu Formation in northern Anhui. In the formation, a great number of calcareous trider sponge spicules were discovered in a distal storm turbidity sequence, which have provided further evidence for the correlation of the Sinian Systems in North and South China from a view point of palaeontology.     

贵州兴义雄武背斜菁角地区龙潭组含铀砂岩地球化学特征及其意义

菁角地处于兴义市雄武背斜核部南东翼南西段,大地构造位置位于扬子板块与华南板块的结合部.前人主要对该地区的金矿进行了矿点地质特征、构造特征、矿体形态等方面的研究,但对岩石学特征、铀的赋存形式以及地球化学特征研究较少.本次研究利用TIMA扫面、显微镜下观察、地球化学分析等方法对矿石、围岩的岩石学特征、地球化学特征、风化作用和分选、源区岩石类型、铀的赋存形式等方面进行探究.TIMA扫面以及显微镜下观察的结果表明铀的赋存形式是以弥散状充填进黏土化(高岭石)裂隙中.菁脚地区地球化学分析显示,龙潭组砂岩中w(SiO2)为51.30％～91.55％,围岩主要类型为亚岩屑砂岩,矿石以及矿化岩石为岩屑砂屑岩,CIA(73.83～82.53)以及ICV指数表明矿石及矿化岩石较围岩成熟度高、风化程度强.测试样品均有较强的U正异常,含量为4.78～772.00×10-6,且U与∑REE,Sb元素呈现明显正相关,Zr与∑REE呈强的正相关(R=1).菁角地区铀的来源是热液在上升过程中萃取围岩中的铀,沿着层间构造破碎带充填进成熟度较高的黑色砂岩中富集而成,结合菁角地区岩石学特征、地球化学特征以及铀的赋存形式,推测菁脚金(铀)矿床为低温热液矿床.     

Identification of coastal water quality by statistical analysis methods in Daya Bay, South China Sea

In this paper, cluster analysis (CA), principal component analysis (PCA) and the fuzzy logic approach were employed to evaluate the trophic status of water quality for 12 monitoring stations in Daya Bay in 2003. CA grouped the four seasons into four groups (winter, spring, summer and autumn) and the sampling sites into two groups (cluster DA: S1, S2, S4-S7, S9 and S12 and cluster DB: S3, S8, S10 and S11). PCA identified the temporal and spatial characteristics of trophic status in Daya Bay. Cluster DB, with higher concentrations of TP and DIN, is located in the western and northern parts of Daya Bay. Cluster DA, with the low Secchi, is located in the southern and eastern parts of Daya Bay. The fuzzy logic approach revealed more information about the temporal and spatial patterns of the trophic status of water quality. Chlorophyll a, TP and Secchi may be major factors for deteriorating water quality.     

山东地震台网监测预警能力评估分析

国家地震烈度速报与预警项目已进入试运行阶段,山东全省作为重点预警区,其预警能力直接关系山东及其周边地区的预警效能。为精确评估山东地震台网的监测预警能力,以本台网所记录到的波形数据为基础,将仪器最大概率峰值位移作为背景噪声评估指标获得山东地震台网的监测能力。在此基础上,考虑到预警时效性需求,系统评估了山东地震台网中,由125台速度计组成的测震台网、由152台加速度计组成的强震台网、由1198台烈度仪组成的烈度台网及其融合网的预警最小震级和首报时间。结果表明,山东地震台网平均监测能力达到M_L0.4,最小值可达M_L-0.2,最大值可达M_L1.1; 测震、强震和烈度台网“三网”融合后预警最小震级、首台触发后和震后的预警时间平均值分别约为M_L2.2、3s和5s,“三网”融合进行预警的策略可以满足地震预警“稳、准、快”的要求。