阴山地区印支期碱性侵入岩岩石地球化学特征   总被引：17，自引：2，他引：17  

阎国翰  谭林坤  许保良  牟保磊  邵宏翔  陈廷礼  童英  任康绪  杨斌 《岩石矿物学杂志》2001,20(3):281-292

通过系统的矿物学、岩石学、地球化学研究，确立了阴山地区印支期碱性岩在空间上分为南北两条近东西走向的岩带。南带以霓辉正长岩为主，北带以碱性正长岩为主。南北两带岩体均富集轻稀土元素、大离子亲石元素和高场强元素，而Cr、Ni等相容元素含量很低。结合Nd、Sr、Pb同位素特征，认为该地区印支期碱性岩源自富集地幔，并受到不同程度的地壳物质混染。  相似文献   

地震勘探方法在江西九江-瑞昌地区寻找隐伏岩(矿)体的应用及效果   总被引：1，自引：0，他引：1  

张虎生  张炎孙  沈健 《物探与化探》2001,25(4):279-284

提供了地震勘探方法在金属矿区寻找隐伏火成岩(矿)体的应用技术和地质成果。通过钻探工程验证,其结果与地震解释推断的结论有较好的吻合。这种尝试对拓宽地震勘探服务领域有重大意义。  相似文献   

山东淄博地区奥陶系层序地层划分和层序界面的识别标志   总被引：2，自引：0，他引：2  

陈建强  胡树庭  杨欣德 《现代地质》2001,15(3):247-253,T001

研究区为华北地台东部奥陶系发育最全的地区之一。区内出露下、中奥陶统 (两河口阶至宝塔阶 ,时限 4 95～ 4 4 5Ma)。岩石地层划分为三山子组和马家沟组。通过对野外剖面系统的观测 ,按碳酸盐岩台地层序地层的研究方法 ,识别出区内奥陶系 8个三级层序 (OSq1-OSq8)和 4种层序界面标志。平均每个三级层序延限约 6Ma ,OSq1由三山子组B段 (TST)和A段 (HST)组成。马家沟组含东黄山段、北庵庄段、土峪段、五阳山段、阁庄段、八陡段和新汶段。东黄山段至土峪段含 2个层序 (OSq2和OSq3 )。五阳山段和阁庄段包含 3个层序(OSq4 -OSq7)。八陡段 (TST)和新汶段 (HST)组成最上部一个层序 (OSq8)。通过与河北唐山等地区同期地层的对比 ,提出华北地台下、中奥陶统 (两河口阶至宝塔阶 )可划分为 11个三级层序 ,探讨了华北地台下、中奥陶统层序差异性的可能的控制因素。  相似文献   

赣东北地区浅变质岩中微古植物及其形成时代讨论   总被引：10，自引：2，他引：10  

文子才  楼法生  黄志忠  吴新华 《现代地质》2001,15(3):281-289

赣东北地区大面积出露一套浅变质岩系 ,该套地层由于缺乏可靠的化石资料 ,其时代归属一直存在很大的争议。随着 1∶5万区调工作的开展 ,相继获得了一批微古植物资料 ,并对所获得的这些资料进行了系统的整理和研究。在研究区内共存在微古植物 73属 173种 ,据统计 ,其所代表的时代绝大部分为中新元古代。根据微古植物组合 ,结合地层层序及有关同位素的测定年龄数据 ,认为研究区浅变质岩系的形成时代应为中新元古代。  相似文献   

Transition of Quaternary glacial cyclicity in deep-sea records at Nansha, the South China Sea     

WANG Pinxian  TIAN Jun  CHENG Xinrong 《中国科学D辑(英文版)》2001,44(10):926-933

High-resolution oxygen isotope records over the last 2249 ka (MIS 1–86) have been obtained from cores of the upper section (105.08 m) at ODP Site 1143 (water depth of 2772 m) drilled in the Nansha area, southern South China Sea. The sampling resolution is at about 2 ka intervals, resulting in one of the best oxygen isotope records over the global ocean. The oxygen isotope curves, displaying details in the Pleistocene glacial cycles, have revealed a nearly 300 ka long stage of transition from a predominant 40 ka to 100 ka periodicity. Therefore, the “Mid-Pleistocene Revolution” should be considered as a process of transition rather than an abrupt change. Within the 100 ka glacial cycles, the changes in tropical sea surface water were found to lead those in high-latitude ice sheet. Our comparisons show that the ice sheet expansion and the glacial stage extension in the Northern Hemisphere with the 100 ka cycles must have been driven not by ice sheet itself, but by processes outside the high latitudes of the Northern Hemisphere.  相似文献   

Determination of active units with different kinematic property and their activity pattern in North China based on the data from GPS remeasurements     

杨国华  韩月萍  张凤兰 《地震学报(英文版)》2001,(1)

IntroductionWith the most feasible and powerful technical support provided by the high-precision GPS measurement for the study on horizontal crustal deformation, the obtainment of various-scale horizontal movement data and its study over the whole world is now in the ascendant, and its applicable fields is now expanding successively. In China, besides the GPS monitoring networks for different applications arranged by many agencies and departments, the key scientific project Crustal Movement…  相似文献   

The effects of surface area, grain size and mineralogy on organic matter sedimentation and preservation across the modern Squamish Delta, British Columbia: the potential role of sediment surface area in the formation of petroleum source rocks   总被引：1，自引：0，他引：1  

Rupert S. Adams  R. Marc Bustin   《International Journal of Coal Geology》2001,46(2-4)

Surface sediment samples were collected from the Squamish River Delta, British Columbia, in order to determine the role of sediment surface area in the preservation of organic matter (OM) in a paralic sedimentary environment. The Squamish Delta is an actively prograding delta, located at the head of Howe Sound.Bulk total organic carbon (TOC) values across the Squamish Delta are low, ranging from 0.1 to 1.0 wt.%. The carbon/total nitrogen ratio (C_org/N) ranges from 6 to 17, which is attributed to changes in OM type and facies variations. The <25-μm fraction has TOC concentrations up to 2.0 wt.%, and a C_org/N ratio that ranges from 14 to 16. The 53–106-μm fraction has higher TOC concentrations and C_org/N ratios relative to the 25–53-μm fraction. The C_org/N ratio ranges from 9 to 18 in the 53–106-μm fraction and 5.5–10.5 in the 25–53-μm fraction. Surface area values for bulk sediments are low (0.5–3.0 m²/g) due to the large proportion of silt size material. Good correlation between surface area and TOC in bulk samples suggests that OM is adsorbed to mineral surfaces. Similar relationships between surface area and TOC were observed in size-fractionated samples. Mineralogy and elemental composition did not correlate with TOC concentration.The relationships between surface area, TOC and total nitrogen (TN) can be linked to the hydrodynamic and sedimentological conditions of the Squamish Delta. As a result, the Squamish Delta is a useful modern analogue for the formation of petroleum source rocks in ancient deltaic environments, where TOC concentrations are often significantly lower than those in source rocks formed in other geological settings.  相似文献   

中国东南沿海中-新生代玄武岩微量元素和Nd-Sr-Pb同位素研究   总被引：8，自引：4，他引：8  

谢昕  徐夕生  邹海波  邢光福 《岩石学报》2001,17(4)

本文对中国东南沿海不含幔源包体的中生代玄武岩和含幔源包体的新生代玄武岩进行了微量元素和Nd-Sr-Pb同位素对比研究。中生代玄武岩呈Ta、Nb和Hf负异常,低Ce/Pb、Nb/U比值和高La/Nb比值,与岛弧火山岩和陆壳岩石的微量元素特征相类似,说明在岩浆生成和上升过程中,幔源组分受到了陆壳组分的混染。新生代玄武岩呈Ta、Nb正异常和Pb负异常,高Ce/Pb、Nb/U比值和低La/Nb比值,与海岛玄武岩(OIB)相类似,Nd-Sr同位素成分与夏威夷玄武岩类似,因而它们未受明显的陆壳混染。143Nd/144Nd与206Pb/204Pb之间的负相关关系和87Sr/86Sr与206Pb/204Pb之间的正相关关系说明本区新生代玄武岩起源于中等亏损程度的软流圈地幔,并与EMII富集地幔组分发生了混合。  相似文献   

高密度电法在湘西北岩溶石山区找水中的应用   总被引：15，自引：0，他引：15  

杨湘生 《湖南地质》2001,20(3):230-232,236

湘西北岩溶石山区地质构造复杂，岩溶发育且具分布不均匀性，找水难度大，为提高含水构造的异常分辨力，各种物探方法的优化组合中，以高密度电法在确定最佳井位方面发挥了重要作用，它采集的数据量大，对异常特征反映灵敏度高，在湘西北不同的岩溶水文系统中找水，取得了成功的范例。  相似文献   

西南岩溶地区植被喀斯特效应   总被引：57，自引：3，他引：57       下载免费PDF全文

姚长宏  蒋忠诚  袁道先 《地球学报》2001,22(2):159-164

西南岩溶地区是我国主要岩溶带之一，也是世界岩溶研究重点地区，区内因人口众多，植被破坏严重，部分地区因人为作用已经产生一系列的环境问题，本文从岩溶地区植被演替规律出发，针对不同植被生态条件，通过对比不同表层岩溶泉的水化学特征和表层土壤空气CO2（g)（表示呀以气相形式存在）的含量，分析了植被在岩溶区，特别在表层岩溶带的喀斯特效应，由此，一方面可以推动岩溶研究的进一步发展；另一方面可以提高人们的岩溶环境保护意识，从而为西南地区生态恢复提供基础资料。  相似文献