基于地学G~4I系统的元数据分类方法   总被引：1，自引：0，他引：1  

韩聪  路来君 《吉林大学学报(地球科学版)》2006,(Z1)

以实现空间数据的标准化为前提,对空间数据库中元数据管理系统的作用和分类原则进行了探讨,指出了传统的分类方法对于以矿产资源预测为目标的地学系统而言存在着弊端。需要结合矿产资源预测的特点,对空间数据库建设中元数据的分类原则进行补充,提出了面向客户应用即按矿产资源预测目标进行分类,实现对空间数据查询的高效利用。该方法可以在地学G4I系统中得以实施和应用。  相似文献   

从珠江口盆地两口井看伊-蒙混层粘土I/S值加大的时温控制     

邬金华  余素玉  许仕策  刘丽华 《矿物岩石地球化学通报》1998,(4)

在渐进成岩过程中,伊蒙混层粘土的伊利石层和蒙皂石层的含量之比（Ｉ／Ｓ）常随埋深增加而呈幕式加大,但该比值达到４∶１后就变得相对稳定了,直到大约３５０℃,残留的少量蒙皂石层才最后消失［１］。业已证实,自然界中这类粘土的伊利石层（和蒙皂石层）多处在准稳...  相似文献   

The parent of the Quadrantid meteoroid stream     

Iwan P. Williams  & Collander-Brown 《Monthly notices of the Royal Astronomical Society》1998,294(1):127-138

The Quadrantid meteor shower is one of the major showers that produces reliable displays every January. However, it is unique amongst the major showers in still not having its parent uniquely identified. One of the reasons for this may be because the stream, and presumably the parent, lies in a region of the Solar system where near-resonant motion with Jupiter, coupled with potential close encounters, is possible. Such a combination can lead to a rapid dynamical evolution of an orbit. In particular, it may be possible that the orbit of the parent both satisfies the condition for a close encounter and is in resonant motion, while most of the meteoroids cannot satisfy both conditions. This results in the parent evolving away from the bulk of the stream.
To date, two suggestions have been made regarding possible parents for the Quadrantid stream, these being Comet 1491 I and Comet 96P/Machholz. The argument in favour of the first named being the parent is because of the general similarity between the orbits around 1491. The argument for comet 96P/Machholz being the parent is based on the similarity in orbital evolution coupled with a similarity in orbits phase-shifted by 2000 yr. In this paper we suggest that on both counts asteroid 5496 (1973 NA) is more similar to the Quadrantids, and that even if 5496 is not the actual parent in the strict sense that meteoroids are currently being ejected, it is either likely to be a fragment of the parent or the dormant remains of the parent.  相似文献   

漳州地区白垩至纪I型和A型花岗岩中黑云母的矿物学特征   总被引：1，自引：0，他引：1  

陈国安  周珣若 《矿物岩石》1996,(2)

漳州地区白垩纪花岗岩由Ｉ型和Ａ型花岗岩组成，本文对该地区两类花岗岩中黑云母的矿物化学、矿物物理特征进行了系统研究。发现在两类花岗岩中的黑云母矿物学特征存在重大差别，如Ａ型花岗岩中黑云母更富铝、铁、氟及水而贫镁、硅，形成温度及氧逸度较低等。在Ａ型花岗岩中的黑云母穆斯堡尔谱也与Ｉ型不同，四极分裂（Ｑ．Ｓ）较高，且Ｆｅ￣（２＋）在Ｍ＿２位，Ｆｅ（３＋）在Ｔ位占位率也较高。两类花岗岩中的黑云母化学成分随岩浆演化也呈现不同的变化规律。黑云母的矿物学特征可提供花岗岩成因类型的有益信息。  相似文献   

Aspects of diamond mineralisation and distribution at the Helam Mine, South Africa     

N. Mc Kenna  J.J. Gurney  J. Klump  J.M. Davidson 《Lithos》2004,77(1-4):193-208

The diamonds from the Swartruggens dyke swarm are mainly tetrahexahedra, with subsidiary octahedral and cuboid crystals. They are predominantly colourless, with subordinate yellows, browns, and greens. The existence of discrete cores and oscillatory growth structures within the diamonds, together with the recognition of harzburgite, lherzolite, at least two eclogitic and a websteritic diamond paragenesis, variable nitrogen contents, and both Type IaAB and Type Ib–IaA diamonds provides evidence for episodic diamond growth in at least six different environments. The predominance of plastic deformation in the diamonds, the state of nitrogen aggregation, and the suite of inclusion minerals recovered are all consistent with a xenocrystic origin for the diamonds, with the Type Ib–IaA diamonds being much younger than the rest. Mantle storage at a time-averaged temperature of ±1100 °C is inferred for the Type IaAB diamonds. The distribution of mantle xenocrysts of garnet and chromite within the high-grade Main kimberlite dyke compared to the low-grade Changehouse kimberlite dyke strongly suggests that the difference in diamond content is due to an increased eclogitic component of diamonds in the Main kimberlite dyke.  相似文献   

Artificial neural network approach for estimation of surface specific humidity and air temperature using multifrequency scanning microwave radiometer     

Randhir Singh  B. G. Vasudevan  P. K. Pal  P. C. Joshi 《Journal of Earth System Science》2004,113(1):89-101

Microwave sensor MSMR (Multifrequency Scanning Microwave Radiometer) data onboard Oceansat-1 was used for retrieval of monthly averages of near surface specific humidity (Q _a) and air temperature (T _a) by means of Artificial Neural Network (ANN). The MSMR measures the microwave radiances in 8 channels at frequencies of 6.6, 10.7, 18 and 21 GHz for both vertical and horizontal polarizations. The artificial neural networks (ANN) technique is employed to find the transfer function relating the input MSMR observed brightness temperatures and output (Q _a andT _a) parameters. Input data consist of nearly 28 months (June 1999 – September 2001) of monthly averages of MSMR observed brightness temperature and surface marine observations ofQ _a andT _a from Comprehensive Ocean-Atmosphere Data Set (COADS). The performance of the algorithm is assessed with independent surface marine observations. The results indicate that the combination of MSMR observed brightness temperatures as input parameters provides reasonable estimates of monthly averaged surface parameters. The global root mean square (rms) differences are 1.0‡C and 1.1 g kg⁻¹ for air temperature and surface specific humidity respectively.  相似文献   

地籍地块间的空间拓扑关系   总被引：9，自引：4，他引：9  

周晓光  陈军  蒋捷  朱建军 《测绘学报》2003,32(4):356-361

地籍的核心是地块，地块间存在着多种空间关系和时间关系。这些关系是地籍数据更新、信息查询与分析的基础。一个地块可看做2维欧氏空间中的一个面域，但目前对于两个面域间空间拓扑关系的描述方法非常有限，不能区分一个简单地块和一个复合地块(一个大地块中包围一个小地块的地块)间的空间拓扑关系。在Egenhofer等提出的包含空洞的两个面域间空间拓扑关系描述框架的基础上提出了一种描述地块间空间拓扑关系的双四元交模型(Double 4I，简称为D-4I模型)，其特点是用两个四元组矩阵来描述最多包含一个复合地块的两地块间的空间拓扑关系，并用D-4I模型推导了一个简单地块和一个复合地块间的拓扑关系类型，共描述了31种地块间的空间拓扑关系，并总结了在地籍信息系统数据更新和数据质量控制中具有重要意义的7种常见的两个地块间空间拓扑关系。这些拓扑关系的描述与区分澄清了地籍地块间的空间拓扑关系类型，为地籍数据更新操作、地籍信息系统的数据质量控制、信息查询与分析推理等奠定了理论基础。  相似文献   

西昆仑东段北缘花岗岩微量元素及同位素地球化学   总被引：2，自引：0，他引：2  

郭坤一  张传林  王家鑫  董永观  赵宇  王爱国 《吉林大学学报(地球科学版)》2002,32(2):116-121

分布于西昆仑东段北缘的侵入杂岩由辉长岩 -闪长岩 -花岗闪长岩 -花岗岩组成 ,在区域上形成一个近东西向的构造 -岩浆岩带。岩石化学特征显示中酸性侵入岩为钙碱性高钾系列Ⅰ型。岩石的∑REE质量分数变化小 ,为 (178.3～ 2 2 9.0 )× 10 -6。闪长岩和花岗岩的w (LREE ) /w(HREE)分别为 3.8～ 5 .1和 6 .7～ 7.7,具有非常相似的稀土配分曲线 ,微量元素与智利岛弧花岗岩完全相似。岩石的w (14 7Sm) /w (14 4Nd)为 0 .0 94～ 0 .114,w (14 3 Nd) /w (14 4Nd)为 0 .5 12 0 5～0 .5 12 19,变化范围小 ,tDM 为 1381～ 15 35Ma之间 ,εNd(t)变化小 ,平均值为 - 10 .46 ,表明侵入岩为同源演化序列 ,为地壳部分重熔的产物。综合岩石化学、微量元素及同位素地球化学特征 ,认为本区的侵入岩形成于大陆边缘岩浆弧 ,岩浆主要来自古元古代变质地层的部分熔融 ,在上升过程中受到中新元古代中基性火山岩混染。  相似文献   

美国“孤立湿地”保护中的“候鸟规则”及对我国湿地保护的启示     

唐双娥  裘丽 《湿地科学与管理》2021,(1):67-72

在美国,孤立湿地与可通航水域没有水文联系,被认为不属于《清洁水法》中的“水域”,联邦无权管辖。为此,陆军工程兵团制定“候鸟规则”,作为对孤立湿地行使管辖权的依据。美国“孤立湿地”保护中的“候鸟规则”对我国的启示在于:(1)应从水文学角度界定孤立湿地,孤立湿地是指与其它水体缺乏联系、相对孤立的湿地,这更符合我国湿地政策的现状;(2)人工“孤立湿地”受保护,除了需满足一定的水文条件,还须是野生动物事实上的栖息地,不应限于建立“栖息地档案”意义下的野生动物栖息地或纳入野生动物重要栖息地名录的栖息地;(3)孤立的人工湿地如果是国家重点保护野生动物栖息地,其管辖权应由中央行使;(4)国家重点保护野生动物栖息地外的其他孤立湿地,面积达到35 hm2以上,也应由中央管辖。  相似文献   

Sequence stratigraphy of a Middle to Upper Ordovician foreland succession (Ottawa Embayment,central Canada): Evidence for tectonic control on sequence architecture along southern Laurentia     

Nkechi E. Oruche  George R. Dix 《Basin Research》2021,33(1):779-808

The Middle to Upper Ordovician foreland succession of the Ottawa Embayment in central Canada is divided into nine transgressive‐regressive sequences that defines net deepening of a platform succession over ~15 m.y. from peritidal to outer ramp settings, then a return to peritidal conditions over ~3 m.y. related to basin filling by orogen‐derived siliciclastics. With a backdrop of net eustatic rise through the Middle to Late Ordovician, there are several different expressions of structural influence on sequence development in the embayment. During the Middle Ordovician (Darriwilian), foreland‐basin initiation was marked by regional onlap with abundant synsedimentary deformation across a faulted trailing‐margin platform interior; subsequent craton‐interior uplift resulted in voluminous influx of siliciclastics contemporary with local structurally influenced local channelization; then, a formation of a platform‐interior shale basin defines continued intrabasin tectonism. During the Late Ordovician (Sandbian, early Katian), structural influence was superimposed on sea‐level rise as indicated by renewed local development of a platform‐interior shale basin; differential subsidence and thickness variation of platform carbonate successions; abrupt deepening across shallow‐water shoal facies; and, micrograben development coincident with foreland‐platform drowning. These stratigraphic patterns are far‐field expressions of distal orogen development amplified in the platform interior through basement reactivation along an inherited buried Precambrian fault system. Comparison of Upper Ordovician (Sandbian‐lower Katian) sequence stratigraphy in the Ottawa Embayment with eustatic frameworks defined for the Appalachian Basin reveals greater regional variation associated with Sandbian sequences compared to regional commonality in base level through the early Katian.  相似文献