拉拉铜矿含矿岩系地球化学特征及其构造意义   总被引：1，自引：0，他引：1  

周家云  郑荣才  朱志敏  陈家彪  沈冰  李潇雨  罗丽萍 《矿产与地质》2009,23(2)

四川会理拉拉铜矿床是我国著名大型富铜矿床,矿床的形成与古元古代河口群海相火山岩密切相关。河口群火山岩除个别样品Nb/Y较低,其他多数样品有一致高的Nb/Y比值(0.7~3.0),属碱性玄武系列;在Nb/Th-Zr/Nb和Zr/Y-Nb/Y图上,HFSE比值成分点主要投在EM1型富集地幔附近,落入洋岛玄武岩(OIB)范围;火山岩较陡的REE分布型式和"驼峰"状微量元素原始地幔标准化分配型式,以及缺乏Nb、Ta负异常,与大陆玄武岩十分吻合;岩石形成于板内裂谷环境。这些地球化学特征表明,河口群火山岩形成于陆间裂谷,来源于地幔深部,指示了矿床的火山喷流沉积成矿作用。同时,岩石大离子元素和轻稀土元素比值不太稳定,变化较大,Eu负异常与蚀变重晶石、萤石和矿化有关,还暗示了岩石遭受了后期变质作用,以及与之有关的矿床变质成矿成因。  相似文献   

南海张裂过程及其对晚中生代以来东南亚构造的启示——IODP建议书735-Full介绍   总被引：2，自引：1，他引：1  

李春峰  汪品先  Dieter Franke  李家彪  许树坤  Peter Michael  周祖翼  翦知湣  李前裕  刘志飞  耿建华  木村学  阎贫  丘学林  王嘹亮  解习农  吴时国  吴能友 《地球科学进展》2009,24(12):1339-1351

南海的形成揭示了大陆边缘张裂和盆地形成的复杂模式,尽管已经进行了广泛研究,但是关于基底岩石和深海盆沉积层的精确年代数据还很缺乏,这使得对南海张裂年代的估计存在很大的误差,对张裂机制和历史的各种假设没有得到验证.同时只有对南海的张裂过程有了精确地分析与刻画,才能更好地理解西太平洋边缘海盆地的形成以及它们在印支块体受印度-欧亚板块碰撞而向东南挤出、青藏高原隆升中可能起到的作用.2009年正式提交的国际综合大洋钻探计划(IODP)建议书735-Full建议在南海深海盆内的4个站位上实施钻探.这4个站位分布在南海盆地4个不同的次级构造单元上(南海东北部、西北次海盆、东部次海盆和西南次海盆),这样的站位设计会确保完成本建议书的整体研究目标,即揭示南海的张裂历史和它对晚中生代以来东南亚构造的启示.位于南海盆地最东北部的站位有助于确定该区域地壳的属性和验证古南海是否存在,位于西北次海盆的站住可能会提供南海的最早张裂年代,另外2个分别位于东部次海盆和西南次海盆的站位将重点确定2个次海盆的绝对年龄、基底矿物成分与磁化率以及2个次海盆的相对张裂次序.这些站位的水深大约在2 910～4 400 m,钻探深度预计到海底以下大约700～2 200 m,总的钻透深度为5 959 m,其中5 359 m穿透沉积层,另外600 m或400 m钻入基底.所有这些站位的位置是由已有的地球物理观测数据所确定,目前计划收集更多的地质与地球物理数据以满足IODP对井位调查数据的要求.  相似文献   

卫星遥感人工增雨作业条件 I: 对流云   总被引：1，自引：1，他引：0  

徐小红  余兴  朱延年  刘贵华  戴进  岳治国 《气候与环境研究》2012,17(6):747-757

利用卫星反演技术和云微物理分析方法,针对云微物理结构和降水形成过程探讨可播性、播撒方式,通过对不同类型对流云分析,归纳出4类可播云系,分析表明:1)重污染深厚对流云,当云底粒子有效半径小于7 μm、凝结增长带深厚、降水启动厚度大于20℃、碰并增长带薄、无雨胚带、晶化温度低于-30℃时,可播撒吸湿性核或播撒AgI.2)强上升冰雹云,若云外型强对流特征明显、各增长带增长缓慢、无雨胚带、晶化温度低于-30℃,且云顶附近存在明显的有效半径减小带,可播撒吸湿性核或播撒AgI.3)强上升强降水对流云,云底滴较大,通常大于10 μm,碰并增长较为充分,晶化温度低,一般低于-30℃,冰晶化延迟明显,冷云降水发展不充分,通过在0℃层附近播撒AgI促进冷云降水.4)污染性浅薄对流云,当云底有效半径小于10 μm、凝结增长带深厚、碰并增长带薄、无雨胚带、云顶有效半径小于14 μm、云厚3～6km,可播撒吸湿性核.  相似文献   

黄土高原泥流灾害成因及特征   总被引：2，自引：2，他引：0  

马东涛  崔鹏  张金山  李鸿琏 《干旱区地理》2005,28(4):435-440

黄土泥流是戴土地区一类重要的灾害地貌过程,是泥石流的一个特殊类型,是水土流失的一种特殊形式,也是山地环境恶化、水土流失极严重的标志。本文在对黄土泥流这一黄土高原特有的严重水土流失现象的分布、成因、物质组成、动静力学性质、堆积形态等全面系统研究的基础上,对其和一般泥石流与高含沙水流做了初步对比和分析,揭示了黄土泥流灾害的形成规律、运动机制和沉积特征。  相似文献   

流体包裹体在油气地质地球化学中的应用   总被引：13，自引：3，他引：10  

张铭杰唐俊红  张同伟吕宗刚 杨荣生 《地质论评》2004,50(4):397-406

流体包裹体研究是油气形成和成藏定量化研究的重要手段。本文总结了油气藏中流体包裹体的地质地球化学意义及其在石油、天然气研究中的应用,探讨了烃源岩和储层流体包裹体在确定源岩演化、沉积环境、有机母质类型、成熟度、油气运移充填期次等方面的应用,指出目前流体包裹体油气地球化学研究应关注的几个前沿方向：①在流体包裹体分析实验技术中,单个包裹体分析技术在油气地质定量化研究中具有重要的作用;②通过有机包裹体自然剖面与模拟实验对比研究烃类流体运移分馏,为建立油气成藏过程地球化学示踪指标提供基础参数;③通过储层中不同期次有机包裹体的化学组成、同位素组成、生物标志化合物与圈闭中已经聚集成藏的油气地球化学特征的对比研究,确定圈闭中油气的成因、来源和充填过程;④有机包裹体成烃作用研究为碳酸盐岩生烃和深层油气成因理论提供依据;这些方向的研究成果为深化油气理论、提高勘探水平具有重要意义。  相似文献   

东营凹陷高青-平南断裂带幔源流体活动特征及其成藏效应   总被引：6，自引：0，他引：6  

曾溅辉金之钧  张刘平 《地质论评》2004,50(5):501-506

东营凹陷高青-平南断裂带为幔源流体运移的主要通道,该幔源流体主要为岩浆(岩)和CO2气体。高青-平南断裂带幔源流体活动方式和活动强度存在着时间和空间上的差异,该断裂带在古近纪-新近纪至少经历了四期富CO2幔源流体活动。高青-平南断裂带富CO2幔源流体对油气成藏的影响主要表现在：①直接形成无机CO2气藏;②通过能量——热的作用和物质,即CO2的加入,影响水-岩相互作用的强度和方向,从而改善油气储集层的物性;③在一定程度上提高源岩的排烃效率,增加油气的运移速率。  相似文献   

藏北改则--班戈地区下白垩统多巴组的高频旋回沉积特征与盆地性质   总被引：5，自引：1，他引：4       下载免费PDF全文

王冠民  钟建华  王建平  陈清华 《地质科学》2004,39(3):346-355

西藏北部改则——班戈地区的下白垩统多巴组中所发育的Ⅴ级旋回表现出3种垂向沉积序列:潮坪相碎屑岩沉积序列(Ⅰ)、浅海相碳酸盐岩沉积序列(Ⅲ)和碳酸盐岩、陆源碎屑岩混合沉积序列(Ⅱ)。其中序列Ⅰ-1和Ⅲ是正常的沉积水体向上变浅的沉积序列,而序列Ⅱ具有明显的陆源碎屑先进积后退积的特征,可进一步分成3个亚类:Ⅱ-1、Ⅱ-2和Ⅱ-3。横向上从南部物源区向北呈Ⅰ→Ⅱ-1→Ⅱ-2→Ⅱ-3→Ⅲ的变化过程。结合盆地构造背景和沉积特征,本文提出多巴组高频旋回的形成与弧背盆地南部冲断带的冲断作用相对应。冲断作用期,物源区粗碎屑物质大量进积,大于盆地基底沉降速率,沉积水体逐渐变浅;冲断间歇期,物源区碎屑物质的供应迅速减少,基底沉降速率逐渐大于碎屑物质的进积速率,沉积水体又有所加深。  相似文献   

The thermal structure and the location of the snow line in the protosolar nebula: Axisymmetric models with full 3-D radiative transfer     

M. Min  C.P. Dullemond  C. Dominik 《Icarus》2011,212(1):416-426

The precise location of the water ice condensation front (‘snow line’) in the protosolar nebula has been a debate for a long time. Its importance stems from the expected substantial jump in the abundance of solids beyond the snow line, which is conducive to planet formation, and from the higher ‘stickiness’ in collisions of ice-coated dust grains, which may help the process of coagulation of dust and the formation of planetesimals. In an optically thin nebula, the location of the snow line is easily calculated to be around 3 AU, subject to brightness variations of the young Sun. However, in its first 5-10 myr, the solar nebula was optically thick, implying a smaller snowline radius due to shielding from direct sunlight, but also a larger radius because of viscous heating. Several models have attempted to treat these opposing effects. However, until recently treatments beyond an approximate 1 + 1D radiative transfer were unfeasible. We revisit the problem with a fully self-consistent 3D treatment in an axisymmetric disk model, including a density-dependent treatment of the dust and ice sublimation. We find that the location of the snow line is very sensitive to the opacities of the dust grains and the mass accretion rate of the disk. We show that previous approximate treatments are quite efficient at determining the location of the snow line if the energy budget is locally dominated by viscous accretion. Using this result we derive an analytic estimate of the location of the snow line that compares very well with results from this and previous studies. Using solar abundances of the elements we compute the abundance of dust and ice and find that the expected jump in solid surface density at the snow line is smaller than previously assumed. We further show that in the inner few AU the refractory species are also partly evaporated, leading to a significantly smaller solid state surface density in the regions where the rocky planets were formed.  相似文献   

Lofted charged dust distribution above the Moon surface     

Vladimir Pines  Marianna Zlatkowski  Arnon Chait 《Planetary and Space Science》2011,59(14):1795-1803

We developed kinetic theory for the charging processes of small dust grains near the lunar surface due to interaction with the anisotropic solar wind plasma. Once charged, these dust grains, which are exposed to the electric field in the sheath region near the lunar surface, could loft and distribute around such heights off the surface where they reach equilibrium with the local gravitational force. Analytical solutions were derived for the charging time, grain floating potential, and grain charge, characterizing the charging processes of small dust grains in a two-component and in a multi-component solar wind plasma, and further highlighting the unique features presented by the high streaming plasma velocity. We have also formulated a novel kinetic theory of sheath formation around an absorbing planar surface immersed in the anisotropic solar wind plasma in the case of a negligible photoelectric effect and presented solutions for the sheath structure. In this study we combined the results from these analyses and provided estimates for the size distribution function of dust that is expected to be lofted in regions dominated by the solar wind plasma, such as near the terminator and in nearby shadowed craters. Corresponding to the two dominant streaming velocity peaks of 300 and 800 km/s, mean dust diameters of 500 and 350 nm, respectively, are expected to be found at equilibrium at heights of relevance to exploration operations, e.g., around 1.5 m height off the lunar surface. In shadowed craters near the terminator region, where isotropic plasma should be dominating, we estimate mean lofted dust diameter of 800 nm around the same 1.5 m height off the lunar surface. The generally applicable solutions could be used to readily calculate the expected lofted size distribution near the lunar surface as a function of plasma parameters, dust grain composition, and other parameters of interest.  相似文献   

Impact angle influence in high velocity dust collisions during planetesimal formation     

Jens Teiser  Markus Küpper 《Icarus》2011,215(2):596-598

We have examined the influence of impact angle in collisions between small dust aggregates and larger dust targets through laboratory experiments. Targets consisted of μm-sized quartz dust and had a porosity of about 67%; the projectiles, between 1 and 5 mm in diameter, were slightly more compact (64% porosity). The collision velocity was centered at 20 m/s and impact angles range from 0° to 45°. At a given impact angle, the target gained mass for projectiles smaller than a threshold size, which decreases with increasing angle from about 3 mm to 1 mm. The fact that growth is possible up to the largest angles studied supports the idea of planetesimal formation by sweep-up of small dust aggregates.  相似文献