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941.
西南印度洋中脊表层沉积物非碳酸盐组分的粒度特征及其地质意义 总被引:1,自引:0,他引:1
The carbonate-free fraction of 20 surface sediments collected from the ultraslow-spreading Southwest Indian Ridge(SWIR) was studied by grain size analysis and mineralogical analysis with X-ray powder diffraction(XRD),stereo microscopy and scanning electron microscopy(SEM). The characteristics of the carbonate-free fraction of the sediments were obtained, and related influential factors were discussed. The results show that the mean grain size of this fraction is in 1.96Φ–8.19Φ, with poorly sorting and unimodal, bimodal or irregular bimodal distribution patterns. Four grain size end members of the fraction are derived with the End Member Model method. The finest end member EM1 shows a significant contribution of terrigenous materials of the aeolian input and sediment carried by the bottom current. End member EM2 with medium size mainly reflects sediment of a siliceous bioclast origin. EM3 and EM4 are interpreted as representing the coarser volcanic materials related to bedrock weathering or volcanic activities. Multi-provenance is the dominant factor controlling the grain size pattern of the carbonate-free fraction of the sediments in that area. In addition, sediment transport processes such as the bottom current and wind are the minor factors that influence the grain size distribution of the carbonate-free fraction sediments. 相似文献
942.
城市地质环境评价是城市规划和场地选址的基础 .以兰州市为例 ,以地理信息系统软件ARC/INFO为开发平台 ,建立了城市地质环境基础数据库 ,将城市用地类型分为高层建筑用地、多层建筑用地、低层建筑用地、垃圾填埋用地及自然保护用地 ,系统分析了各类用地与地质环境协调性评价的指标体系 ,采用层次分析法建立了评价模型 ,对不同的用地类型进行了评价 .结果表明GIS与评价模型的结合可以快捷、准确地进行城市建设用地与地质环境的协调性评价 相似文献
943.
The distribution of Oil & gas fields shows their close relationship with the most active tectonic regions. This is not a coincidence but having a scientific reasons. The crustal active regions, refer to the places where the active natural earthquake, volcanic activities, underground water happened, and the areas of the leaking off of natural gas to the surface of the crust. The magma of volcanic activities brings the organic "kitchen range body" hydrocarbon- generating model and inorganic genetic hydrocarbon to the regions covered by volcanic rock. Underground water brings a catalytic hydrocarbongenerating model for organic matter, and the leaking- off of H2 and CO2 contributes a synthetic hydrocarbon - generating model. Volcanic activities bring the assemblage of Source, Reservoir and Seal formed by the sediments and magma the sedimentary basins, and the hydrocarbon - generating system with a "water - volcano" binary structure is formed. All these conditions are favorable and excellent for the formation of oil & gas fields. The distribution of American oil & gas fields have very close relationship with the mines of Fe, Mn, Ct, Mo, W and V, deposits of Zn, Cu, V, Pb, Al and Hg, and the deposits of fluorite, sulfur, potassium salt, phosphate and halite, and the distribution of sulfate- chloride of river water. The reason why few oil & gas fields discovered in the regions covered by volcanic rock in western America maybe because of the view of "inconsistency between petroleum and volcano". Further more, It's very difficult to carry out a geophysical exploration in such kinds of regions.This paper examined a few hydrocarbon-generating models (systems) mentioned above and came up with some fresh ideas on the exploration in the areas covered with volcanic rocks. 相似文献
944.
A harmful algae bloom (HAB) is a dense aggregation of algae in a marine or aquatic environment that can result in significant
environmental problems. To forecast the occurrence of HAB, development of a rapid and precise detection method is urgently
required. In this study, two Skeletonema costatum-like diatoms (SK-1 and SK-2), were identified morphologically under a light microscope, and detected using fluorescent in situ hybridization (FISH). Strain SK-1 was isolated from a frequently HAB affected area of the East China Sea, and strain SK-2
from an aquatic farm in Qingdao, China. Fluorescent DNA probes were designed that were complementary to the ITS sequence (including
5.8S rDNA) of strain SK-1. After hybridization, strong green fluorescence was observed in cells of strain SK-1 under an epifluorescence
microscope; however, no such fluorescence was observed with strain SK-2, which indicates that probes hybridized only the DNA
of the target strain, SK-1, in species-specific manner, and that the two strains do not belong to a same species. This finding
was confirmed by ITS sequence analysis. The FISH technique used in this study was sensitive, simple, and rapid, and is a promising
tool for detecting target HAB species in natural environments. 相似文献
945.
946.
库车坳陷克拉2气田异常流体压力演化史 总被引:6,自引:4,他引:6
根据克拉2气田现今实测地层压力分析了异常高压发育的特征,并通过流体包裹体测试求取包裹体形成时期的古压力。计算结果表明:下白垩统和古近系库姆格列木群砂岩储层在距今8~6Ma(康村组沉积期末)时,古压力系数大致为1.09~1.18,发育过剩压力为4.6~9.6MPa的异常高压。在此基础上,以古、今压力数据为约束条件,利用数值模拟技术定量恢复出下白垩统与侏罗系异常流体压力的演化历史。研究发现:下白垩统储层流体压力经历了沉积型异常流体压力形成发展(白垩纪-库车组沉积期末)和沉积型异常流体压力萎缩—构造挤压型异常流体压力孕育(库车组沉积期末至今)两个阶段。康村组沉积早期沉积型超压开始出现,库车组沉积期末达到顶峰,过剩压力达40~50MPa;此后,在沉积型超压萎缩—构造挤压型超压孕育过程的耦合下,过剩压力曾降至25~30MPa,更新世起超压略有升高。侏罗系流体压力演化较为简单,吉迪克组沉积期开始出现超压,至库车组沉积期末达到高峰,此后异常高压逐渐萎缩。在克拉2气田的主要成藏时期(距今3~1Ma),烃源岩较储层具有更高的异常压力,源—储压力差为10~30MPa。 相似文献
947.
北祁连东段冷龙岭地区毛藏寺岩体和黄羊河岩体的岩石成因及其构造意义 总被引:5,自引:0,他引:5
文中研究了北祁连东段冷龙岭地区毛藏寺岩体和黄羊河岩体的年代学、地球化学和Sr-Nd同位素组成。毛藏寺岩体主要岩石类型为花岗闪长岩。锆石U Pb定年获得花岗闪长岩岩浆结晶年龄为(424±4) Ma。花岗闪长岩具有高的Mg#(约55),K2O/Na2O=0.77~0.91,A/CNK=0.92~0.94,表明岩石属准铝质。在微量元素组成上,花岗闪长岩富集LILE、亏损HFSE,轻重稀土分异明显[(La/Yb)N=16.9~19.5],具有弱的Eu负异常(Eu/Eu*=0.75~0.83);花岗闪长岩具有ISr=0.706 3~0.706 5,εNd(t) =-1.5~-1.1,TDM=1.10~1.16 Ga。这些地球化学特征和Sr Nd同位素组成表明,花岗闪长岩岩浆源区为基性下地壳变玄武质岩石,但在成岩过程中有少量幔源物质的加入。黄羊河岩体主要由钾长花岗岩组成,其岩浆结晶年龄为(402±4) Ma。岩石富碱(K2O+Na2O=6.91‰~7.66%),K2O/Na2O>1,A/CNK=0.97~1.05。钾长花岗岩富集LILE及HFSE,轻重稀土元素分馏中等[(La/Yb)N =10.6~17.8],并具有明显的负Eu异常(Eu/Eu*=0.43~0.68),表明钾长花岗岩具有铝质A型花岗岩的地球化学特征。钾长花岗岩具有ISr=0.710 3~0.711 3,εNd(t)=-6.7~-6.0,TDM=1.46~1.55 Ga,反映岩浆主要来自地壳中长英质物质的部分熔融。冷龙岭地区花岗岩类的岩石成因及其岩浆演化揭示了北祁连山造山带从加里东早期的挤压构造体制向加里东晚期的伸展构造体制的演化。这些花岗岩类形成于碰撞后构造背景,岩浆的产生可能与俯冲的北祁连洋板片的断离作用有密切联系。 相似文献
948.
949.
罗德里格矩阵在共线方程严密解法中的应用 总被引:1,自引:1,他引:1
张森林 《武汉大学学报(信息科学版)》1987,12(1):81-91
在共线方程严密解法中,人们习用的是以方位元素Xs,Ys,Zs,φ,ω,κ为未知数的严密公式。本文则以罗德里格旋转矩阵的三个独立元素b,a,c取代角方位元素φ,ω,κ,并推导了相应的误差方程式。理论表明,新方法在组成旋转矩阵和计算误差方程系数中只需作加、减、乘、除等运算而不需解求三角函数,因而节省了计算工作量。 相似文献
950.