华北克拉通基性火山岩高场强元素对Ar-Pt界限及新生代地幔源区特征的示踪   总被引：5，自引：0，他引：5       下载免费PDF全文

刘勇胜  高山  骆庭川 《地球科学》1998,23(5):91

华北克拉通不同时代基性火山岩存在向富集方向演化的趋势,并出现明显的Ａｒ－Ｐｔ界限和新生代异常．元古宙基性火山岩比太古宙富集大部分高场强元素（ＨＦＳＥ）和轻稀土元素（ＬＲＥＥ）,ＲＥＥ分异程度显著增加,而且相容性接近的不相容元素（如Ｎｂ,Ｔａ）的相对不相容性发生了改变．新生代玄武岩ＨＦＳＥ及Ｎｉ高度富集,ＲＥＥ强烈分异,δ（Ｅｕ）值最高．Ａｒ－Ｐｔ界限可能与地幔熔融时物理条件（如氧逸度）的改变和地幔富集作用有关．新生代玄武岩独特的地球化学特征可能主要反映了地幔源区的特殊性———“似ＯＩＢ型”富集地幔,其形成既可能有携带远洋沉积物的俯冲古老玄武岩洋壳部分熔融残余的贡献,也可能有直接循环（如通过拆沉作用）的陆壳物质的贡献,同时还可能涉及了地幔柱活动的影响．  相似文献   

岩体结构面水力学模型及应用     

金风生  马凤山 《水文地质工程地质》1998,25(2):26-29

本文提出岩体结构面适应性平行板模型和该模型的参数确定方法——三段压水试验新解释,新的模型有益于克服将结构面圆盘模型应用于地下水模拟中的局限性;基于结构面起伏度对地下水流动的影响,导出了起伏度修正系数解析表达式。  相似文献   

东营凹陷油气运聚古地下水动力场剖面数值模拟     

谢石连  汪民 《水文地质工程地质》1998,25(2):34-37

本文对东营凹陷油气运聚古地下水动力场剖面数学模型的建立、古水文地质参数的再造、模拟初始值的恢复进行了阐述。在此基础上,进行了东营凹陷油气运聚古地下水动力场剖面数值模拟。模拟结果与已知油田的分布具有较好的一致性。推断的东营凹陷油气聚集有利地段,可以作东营凹陷油气田进一步勘探开发的依据。  相似文献   

松树沟元古宙蛇绿岩Nd、Sr、Pb同位素地球化学特征   总被引：22，自引：1，他引：21       下载免费PDF全文

周鼎武  董云鹏  刘良  张旗  张宗清 《地质科学》1998,33(1):31-38

松树沟蛇绿岩中镁铁质岩的Sm-Nd全岩等时年龄为1030±46Ma,∈_Nd(t)=+5.7,模式年龄在1422-1271Ma之间,矿物的内部等时年龄为983±140Ma。全岩等时年龄为其形成上限,矿物内部等时年龄为其变质年龄,说明该蛇绿岩形成于中元古代中、晚期。镁铁质岩的∈_Nd(t)在+4.2-+6.9之间,是DMM与EMI两个地幔端元的混合产物;²⁰⁶Pb/²⁰⁴Pb在18.06-18.66之间,²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/²⁰⁴Pb值较高,分别在15.55-15.60和37.59-38.38之间,²⁰⁷Pb/²⁰⁴Pb和²⁰⁸Pb/²⁰⁴Pb对²⁰⁶Pb/²⁰⁴Pb的关系表明,岩浆源于具DUPAL异常的源区,(²⁰⁷Pb/²⁰⁴Pb)_i相对(²⁰⁸Pb/²⁰⁴Pb)_i更偏离NHRL可能是变质流体作用的反映。∈_Sr(t)值较高且变化大,可与蛇绿岩类比,⁸⁷Sr/⁸⁶Sr比值变化大,可能与海水蚀变作用有关。据此推测,松树沟蛇绿岩代表洋壳残片。  相似文献   

夯扩桩沉管控制贯入度计算法     

周武阶 《地质与勘探》1998,34(5):53-55

通过改造格尔谢万诺夫打桩公式,提供了夯扩桩沉管控制贯入度计算表达式,在此 ,介绍了沉积控制贯入度在夯扩桩设计和施工中的用途,并举例验证。  相似文献   

The Wave Energy Concentration at the Agulhas Current off South Africa   总被引：3，自引：0，他引：3  

Lavrenov  I. V. 《Natural Hazards》1998,17(2):117-127

The case of a freak wave collision with the ship in the Agulhas current is described. The explanation of the appearance of the freak wave as a result of wind-wave transformation in the Agulhas current is given. Swell is captured and intensified by the counter-current and is located in the neighbourhood of the maximum value of the current velocity, as a result of which there is a great concentration of wave-energy density. The superposition of wind and sea with swell transformed by the current promotes the formation of the freak waves. Using a simple mathematical analysis, an optimal ship track is proposed which could reduce the risk of collision with a freak wave.  相似文献   

黄河下游引黄区沉沙处理运行方案分析研究^*     

唐登银  高善明 《地理研究》1998,17(4):401-408

黄河是多沙性河流,引黄必带进大量泥沙,沉沙池沉粗排细,能有效处理泥沙。当沉沙池淤满,失去自流沉沙作用时,采用"以挖待沉"可以延长灌区运行年限,但没有扬水沉沙方案优越。根据黄河下游地上河的特殊地貌条件,如果能在河漫滩上建沉沙池,可以解决沉沙占地的难题。  相似文献   

河北省环渤海地区生态经济协调发展的人工神经网络分析   总被引：11，自引：2，他引：9  

李双成  高伟明  刘濂 《地理研究》1998,17(4):352-359

区域社会经济系统的可持续发展依赖于系统成分的协调程度及与生态系统的增益耦合。传统研究多以系统动力学或多目标规划模型来调控系统。文中以人工神经网络模型来模拟和映射社会经济系统的结构和功能。通过构建、训练、测试、运行河北省环渤海地区生态经济网络模型,提出了以减缓发展速度、降低能量投入水平等措施来达到生态系统和社会经济系统协调发展的目标。  相似文献   

浙赣皖交界区新元古代火山-沉积岩系的比较——有关火山作用同期异相的探讨     

唐红峰  李武显  周新民 《地质学报》1998,72(1)

本文综合野外地质、同位素年代学和岩石地球化学资料,对浙赣皖交界区,即江南造山带东段发育的众多新元古代火山—沉积岩系进行了对比研究。从岩石组合及其大地构造含义和火山作用同期异相的观点加以认识.揭示它们的内在联系,为该区地层单元的清理和归并提供依据。  相似文献   

Tectonic implications of new age data for the Meratus Complex of south Kalimantan, Indonesia     

Koji Wakita  Kazuhiro Miyazaki  Iskandar Zulkarnain  Jan Sopaheluwakan  & Prihardjo Sanyoto 《Island Arc》1998,7(1-2):202-222

Cretaceous subduction complexes surround the southeastern margin of Sundaland in Indonesia. They are widely exposed in several localities, such as Bantimala (South Sulawesi), Karangsambung (Central Java) and Meratus (South Kalimantan).
The Meratus Complex of South Kalimantan consists mainly of mélange, chert, siliceous shale, limestone, basalt, ultramafic rocks and schists. The complex is uncomformably covered with Late Cretaceous sedimentary-volcanic formations, such as the Pitap and Haruyan Formations.
Well-preserved radiolarians were extracted from 14 samples of siliceous sedimentary rocks, and K–Ar age dating was performed on muscovite from 6 samples of schist of the Meratus Complex. The radiolarian assemblage from the chert of the complex is assigned to the early Middle Jurassic to early Late Cretaceous. The K–Ar age data from schist range from 110 Ma to 180 Ma. Three samples from the Pitap Formation, which unconformably covers the Meratus Complex, yield Cretaceous radiolarians of Cenomanian or older.
These chronological data as well as field observation and petrology yield the following constraints on the tectonic setting of the Meratus Complex.
(1) The mélange of the Meratus Complex was caused by the subduction of an oceanic plate covered by radiolarian chert ranging in age from early Middle Jurassic to late Early Cretaceous.
(2) The Haruyan Schist of 110–119 Ma was affected by metamorphism of a high pressure–low temperature type caused by oceanic plate subduction. Some of the protoliths were high alluminous continental cover or margin sediments. Intermediate pressure type metamorphic rocks of 165 and 180 Ma were discovered for the first time along the northern margin of the Haruyan Schist.
(3) The Haruyan Formation, a product of submarine volcanism in an immature island arc setting, is locally contemporaneous with the formation of the mélange of the Meratus Complex.  相似文献