海原断裂带刺儿沟剖面烘烤次生黄土的光释光测年及其地质意义   总被引：1，自引：2，他引：1  

张克旗  陈杰  刘进峰  尹金辉  王昌盛  王同利 《地震地质》2007,29(2):390-401

选择海原活动断裂带刺儿沟剖面2个烘烤次生黄土样品LEDL0588H和LEDL0365的细颗粒石英,采用改进后的单测片再生法(SAR)和简单多测片再生剂量法(SMAR)进行了一系列实验研究。2个样品细颗粒石英的光释光信号均以快速组分为主,其等效剂量(DE)的预热坪实验表明,在180～260℃的预热温度范围内均能获得基本一致的DE值。SAR法测量不同预热温度下的释光感量变化、剂量恢复实验和LN/TN比值的关系以及SMAR法测量中LN/TN比值与预热温度的关系的研究表明,文中所采用的流程能有效地校正测量过程中释光信号感量变化。2种方法均适用于采自不同层位的2个烘烤样品细颗粒石英的OSL测年,并获得了非常接近的OSL年龄。2个样品最后一次被烘烤的时间可能代表的是同一时期的人类活动  相似文献   

Biogenic Accumulations of Uranium in Recent Seas     

Saday Azadolu ALlYEV  Ali SARI 《《地质学报》英文版》2003,77(3):372-381

The objective of this study is to determine the geochemical role of molluscs in the distribution of uranium in the marine ecosystem. Biogeochemical studies are carried out on recent mollusc shells from the Caspian Sea, Sea of Japan, Sea of Marmara, Aegean Sea, Black Sea, Mediterranean Sea, Baltic Sea, and Indian Ocean, which differ from each other in terms of physical, chemical, geographic, and geochemical characteristics. In this study, nine Gastropoda and fifty-four Pelecypoda shells of different species are analyzed to document variations of uranium in seasonal layers, which were formed by the seasonal carbonate-organic phase of molluscs during their entire lives. Shell used in this study principally comprises three layers: upper (outer) prismatic, middle prismatic, and inner (mother-of-pearl) layers. In addition, when possible, the head, the middle, and the lower parts of the shells are used for analyses separately. Also, the biological accumulation rate values for each different mollusc species rel  相似文献   

INITIATION OF SHELL MOTION ON SAND BEDS: AN EXPERIMENTAL STUDY     

Subhasish DEY  Alok KUMAR 《国际泥沙研究》2002,17(4)

1 INTRODUCTION Bivalve shells are found in biologically productive coastal regions encompassing the surf zone, tidal entrance and estuarine waters near the entrances. An example of a beach composed exclusively of shells (about 97% of the surficial sedimentary material) is the beach at John o'Groats in Scotland (Raymond and Hutchins, 1932; Komar, 1976). Southern Gulf Coast of Florida in USA (Runsak et al., 1966; Austin, 1971) and the banks of Lower Medway estuary in England (Kirby,…  相似文献   

Vibration of a thin-walled prolate dome under external water pressure     

Carl T.F. Ross  Philipp Kster  Andrew P.F. Little  Giles Tewkesbury 《Ocean Engineering》2007,34(3-4):560-575

The paper reports on a theoretical and an experimental investigation carried out on a thin-walled hemi-ellipsoidal prolate dome in air and also under external water pressure. The investigation found that there was good correlation between experiment and theory. The theoretical investigation was carried out using the finite element analysis to model both the structure and the fluid. The theoretical investigation used two different programs, one of which was the giant computer program ANSYS and the other was an in-house program developed by Ross. For the shell structure, the ANSYS program used 2 different doubly curved thin-walled shell elements, while the in-house program used a simpler axisymmetric thin-walled shell element. This axisymmetric element allowed a sinusoidal variation of the displacements in the circumferential direction, thus, decreasing preparation and computational time. Agreement between the 3 different finite elements was found to be good. This was found particularly encouraging for the in-house software, as it only took a few hours to set up the computer model, and a few seconds to analyse the vessel, whereas the ANSYS software took several weeks to set up the computer model, and several minutes to analyse the shell dome. The ANSYS software, however, did have the advantage in producing excellent graphical displays in both the pre-processing and post-processing modes.  相似文献   

Dark spots,bubbles, and shells in the lobes of extragalactic radio sources     

Wolfgang Kundt  Lakshmi Saripalli 《Journal of Astrophysics and Astronomy》1987,8(3):211-217

Based on maps of the extragalactic radio sources Cyg A, Her A, Cen A, 3C 277.3 and others, arguments are given that the twin-jets from the respective active galactic nucleus ram their channels repeatedly through thin, massive shells. The jets are thereby temporarily choked and blow radio bubbles. Warm shell matter in the cocoon shows up radio-dark through electron-scattering.  相似文献   

Comet Hale-Bopp: Evolution Of Jets And Shells During March 1997     

SCHWARZ  G.  COSMOVICI  C. B.  CRIPPA  R.  GUAITA  C.  MANZINI  F.  OLDANI  V. 《Earth, Moon, and Planets》1997,78(1-3):189-195

Hundreds of high quality CCD images obtained by the GAT group with the 33.5 cm reflector of the Sozzago Astronomical Observatory (SAS) provide a detailed insight into the temporal evolution of comet Hale-Bopp. The images cover the time period from May 1996 until May 1997 and allowed us to analyze various near nucleus phenomena. Among them are jet structures that were visible from August 1996 until May 1997 and shell structures that could be resolved from February 1997 to May 1997. We concentrate on the morphology of these phenomena during March 1997 and investigated them by radial masking techniques that reveal their precise shape and extent. In particular, polar coordinate representations could be used advantageously to derive numerical parameters of these features. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Characteristics and Genesis of Fine-Clastic Rock-Type Au Deposits in the Liaodong Rift     

YANG DejiangLiaoning Nonferrous Geological Exploration Bureau  State Bureau of Nonferrous Matals Industry  Liuzhou St.  Heping District  Shenyang 《《地质学报》英文版》2000,74(3):570-576

Gold deposits occurring in the Liaodong rift are located in interlayered carbonate rocks and fine-clastic rocks, belonging to the middle and upper parts of the lower Proterozoic. Compared with the Carlin-type Au deposits abroad and gold deposits in Yunnan-Guizhou-Guangxi, Qinling and western Sichuan Province, they are similar in many respects. This paper discusses the geological features of ore-bearing formations and ore-filling structures and metallogenetic characteristics. Through the discussion on the sources of ores, heat and water, it points out that the Au deposits belong to vadose reworked hydrothermal deposits. This conforms to the principle of "mineralization in the neighbouring areas", i.e., the deposits are formed in nearby ore-bearing layers, and the latest hydrothermal event was the main factor in forming the Au deposits.  相似文献   

滇东北会泽超大型铅锌矿床矿质来源与改造成矿作用   总被引：1，自引：0，他引：1       下载免费PDF全文

冉崇英 《高校地质学报》2017,23(4):563

"改造成矿作用"理论是中国科学院涂光炽院士提出的完善矿床成因分类学"四分法"的新理论,是中国学者对世界地球科学的重要贡献。该文根据会泽铅-锌(银、锗)矿床地质地球化学特征,列举其沉积改造的充分证据,用改造成矿的四大要素审视其矿床成因,认同它是典型而独特的沉积—强烈改造矿床,并以重要的宏观地质为依据,注意到峨眉山玄武岩(260 Ma)本身及昆阳群褶皱基底均未赋存一定规模的铅锌矿床,认为玄武岩与基底供给会泽铅锌矿(245~246 Ma)成矿物质有限,成岩与成矿时差太大,且成矿断层切割玄武岩,说明玄武岩成岩在先,铅、锌成矿在后,二者无直接成因联系。对会泽铅锌矿床的物质来源,有主张来自地层、基底、玄武岩或多来源者,但以何者为主,多种金属是否同源尚缺深入讨论,文章特别对地层、基底、峨眉山玄武岩中各成矿元素的含量、富集系数及富集类型进行系统的求算与分析研究,以讨论各种成矿金属的可能来源几率及其对成矿的贡献估计。结果显示:银在各地质体中均高倍富集,可提供充沛矿质,铅次之;锌则相反,多为正常元素或亏损元素,锗、镓、铟亦然,故矿石中的锌、锗、镓、铟,更可能为深部提供。结合大量的微量元素、稀土元素、铅、硫、锶、碳、氢、氧同位素等地球化学资料分析研究,认为地层,特别是震旦—寒武系、泥盆系、下石炭统摆佐组(C1b)与深部是主要的矿质来源,不同金属可同源或异源。矿床受地层岩性与构造的双重控制,与岩浆活动无关,具备改造成矿要素,属典型的沉积—强烈改造铅锌矿床,且具超大、特富、多金属富集的独特性。海西期下石炭统摆佐组已沉积成岩成矿或形成矿源层,后经印支期构造运动强烈改造而超常富集成矿,多掩盖其沉积特征,它属于沉积改造矿床"会泽式"。  相似文献   

Inelastic buckling of thick-walled circular conical shells under external hydrostatic pressure   总被引：1，自引：0，他引：1  

Carl T. F. Ross  David Sawkins  Terry Johns 《Ocean Engineering》1999,26(12):1506

The paper reports on a theoretical and an experimental study into the collapse of three thick-walled circular conical shells, which were tested to failure under external hydrostatic pressure. All three vessels failed by plastic non-symmetric bifurcation buckling. Two theoretical analyses were carried out, both based on the finite element method. One of the theoretical analyses was based on inelastic non-symmetric bifurcation buckling and the other analysis was based on plastic axisymmetric buckling. Both of these theoretical analysis and the experimental observations appeared to indicate that there is a link between plastic non-symmetric bifurcation buckling and plastic axisymmetric buckling.  相似文献   

Equatorial symmetry breaking and the loss of dipolarity in rapidly rotating dynamos     

Ferran Garcia  Ludivine Oruba  Emmanuel Dormy 《地球物理与天体物理流体动力学》2017,111(5):380-393

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