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1.
山东淄博-章丘盆地三叠系时代讨论   总被引:2,自引:0,他引:2  
山东基岩区三叠系一直缺少生物化石依据。前人在该套地层底部发现了铱等元素异常,认为可作为划分其地质时代的依据。笔者在1:25万淄博市幅区域地质调查中,于该地层中首次发现了孢粉化石,结合前人铱等异常特征,经区域对比确定其形成于早-中三叠世,并认为区内孙家沟组相当于华北地区的和尚沟组,刘家沟组则相当于二马营组。  相似文献   

2.
在开展藏北多巴区幅1:25万区域地质调查时,在申扎地区永珠-雄梅-果芒错一带发现了一套沿永珠蛇绿岩带(?)分布,岩性特征及成因环境较为特殊的晚侏罗世-早白垩世地层,建立了日拉组及日拉组索尔碎屑岩单位。  相似文献   

3.
扬子地台西缘攀西地区,晚震旦世-早寒武世为一套连续沉积碳酸盐岩,众多科研文献中时代地层、岩性地层和生物地层的划分各异。在此交变期及其近前后,随之发生诸多地质事件,成为地学研究的热点之一。于宁南等四幅1:5万区调工作中,实测灯影组麦地坪段地层剖面,采集新鲜岩样,测试碳、氧同位素,试从稳定同位素地球化学角度阐述其指示意义,提供研究震旦一寒武纪交变期的地球化学资料。  相似文献   

4.
李永军  杜志刚 《新疆地质》2004,22(2):150-150
哈密库姆塔格沙垄北一带1:5万地质调查区主要为火山岩分布区,化石十分难觅.在以往的地质调查中,该区无化石发现.因而长期以来,这一地区地层的时代确立和区域地质对比均缺乏有力的时代依据.2003年,由新疆维吾尔自治区地质矿产勘查开发局第九地质大队和长安大学地质调查研究院合作开展的“哈密库姆塔格沙垄北1:5万地质矿产调查”中,于库姆塔格沙垄北1:5万图幅区的夹持于火山岩地层中的两套灰岩中,均有重要化石发现。  相似文献   

5.
四川雅安-宝兴地区的侏罗-白垩系   总被引:1,自引:0,他引:1  
根据1∶5万区域地质调查资料,将四川省雅安—宝兴地区的侏罗—白垩系地层,由老至新划分为白田坝组、千佛崖组、沙溪庙组、遂宁组、莲花口组、天马山组、夹关组、灌口组等8个岩石地层单元。描述了层型剖面的层序及岩石组合特征,讨论了生物地层及年代地层问题。对侏罗—白垩系的沉积环境进行了分析,初步划分出河流相、湖泊相、冲积扇相三大类型。  相似文献   

6.
内蒙古阿拉善左旗巴音诺日公地区前寒武系的厘定   总被引:11,自引:1,他引:11  
以巴音诺日公地区4幅1:5万区域地质调查资料为基础,将该区1:20万区调阿拉坦敖包幅、庆格勒幅前寒武纪14个组级地层单位重新厘定为7个(构造)一岩石地层单位,经区域对比,结合同位素测年资料,将其分别归属于中太古界乌拉山岩群,新太古界色尔腾山岩群柳树沟岩组、点力素泰岩组,中元古界渣尔泰山群书记沟组、增隆昌组和阿古鲁沟组,中元古界白云鄂博群哈拉霍疙特组。  相似文献   

7.
分布于措勤县城一带的一套地层在1:100万日喀则幅区调中校划属上新统乌郁群,由下部火山岩和上部沉积岩组成。在1:25万措勘县幅区调中,根据获得的同位素年龄值已将下部火山岩地层划归古新统的典中组,而上部的沉积地层中含圆笠虫等有孔虫化石应属下白垩统。在这一地区还新发现一套陆相碎屑地层,根据其岩性组合、ESR年龄值及区域地层对比,本文将其新命名为上新统洁居纳卓组。  相似文献   

8.
四川雅安——宝兴地区的侏罗—白垩系   总被引:3,自引:0,他引:3  
根据1:5万区域地质调查资料,将四川省雅安-宝兴地区的株罗-白垩系地层,由老至新划分为白田坝组,千佛崖组,沙溪庙组,遂宁组,莲花口组,天马山组,夹关组,灌口组等8个岩石地层单元。描述了层型剖面的层序及岩石组合特征,讨论了生物地层及年代地层问题。对侏罗-白垩系的沉积环境进行了分析,初步划分出河流相,湖泊相,冲积扇相三大类型。  相似文献   

9.
笔者在《岔路口》等四幅1:25万区域地质调查工作中,在红山湖一带从前人所划的石炭系地层中解体出一套二叠系地层,并对其进行了详细的岩石地层、生物地层和层序地层研究,拟新命名为红山湖组,时代为中二叠世。该地层为甜水海微陆块上稳定型的碳酸盐岩建造,与陆块南北两侧二叠系特征截然不同。该套地层的发现填补了微陆块上二叠系地层的空白,对古特提斯多岛洋研究具有重要意义。  相似文献   

10.
西藏西部日松地区多仁组、日松组的建立及其地质意义   总被引:2,自引:0,他引:2  
在班公湖-改则-革吉-带广布-套类复理石-复理石碎屑沉积,总体岩性单调,化石稀少,研究程度极低。对该套地层.尤其上部层位因缺乏年代依据,其时代归属及沉积上限一直争论较大,地层序列划分难以统一。在1:25万日土幅区域地质调查过程中对该套地层进行了详细研究,于中上部层位中采获了较丰富的古生物化石,其时代归属为晚侏罗世。据沉积建造、岩性组合及古地理、古生物面貌特征,宜将其从原木嘎岗日地层分区划出,归入班戈-八宿地层分区,创建为多仁组、日松组。  相似文献   

11.
依据松辽盆地西南部新站地区嫩江组三段孢粉和藻类化石百分含量纵向变化特征,自下而上划分7个能识别水体盐度变化的孢粉和藻类组合:Cyathidites Pinuspollenites Dinogymniopsis组合,指示缩小的微咸水湖相沉积环境;Dinogymniopsis Leiosphaeridia Pinuspollenites组合,代表水域扩大的微咸水湖相沉积环境;Cicatricosisporites Pinuspollenites Botryococcus组合,代表水域缩小的淡水-微咸水湖相沉积环境;Dinogymniopsis Chlamydophorella Taxodiaceaepollenites组合,反映淡水与微咸水频繁交互变化的浅湖相沉积环境;Cicatricosisporites Pinuspollenites Pediastrum组合,代表水域缩小的淡水湖相沉积环境;Nenjiangella Balmula Cyathidites组合,代表水域范围较大的淡水湖相沉积环境;Cyathidites Trilobosporites Botryococcus组合,指示水域缩小的微咸水湖相沉积环境。  相似文献   

12.
The paper describes a mechanical model for estimating the flexural response of a strip footing, supporting a column (imposing a concentrated load), resting on a compacted granular bed overlying a reinforcement layer for example, geogrids, geomats etc. below which lies a loose soil deposit. The footing is idealized as a beam and the reinforcing element is assumed to have finite bending stiffness and negligible frictional resistance. The upper and lower soil layers are idealized by a series of linear and discrete springs (Winkler springs) of different stiffness values. To find the response of such a model the governing differential equations have been derived and expressed in a nondimensional form. A closed form analytical solution of the same has been obtained subjected to appropriate boundary conditions. Using the present approach the resulting solution for a degenerated case of a long beam is found to be identical to the same of Hetenyi (1946, Beams on elastic foundations, University of Michigan press, Ann Arbor, MI). Parametric studies reveal that the ratio of flexural rigidity of upper and lower beam and the ratio of stiffness of the upper and lower soil layers affect significantly the response of the foundation.  相似文献   

13.
14.
Zones of increased concentration formed by a solvent flowing from a source are considered. A matehmatical model for forming such zones is proposed. It takes into account that such a zone is composed of a set of independent particles. Hence the distribution of a substance around the source can be explained by movement of an individual particle. In the model this movement is a continuous semi-Markov process with terminal stopping at some random point in space. Parameters of the process depend on the velocity field of the flow. Forward and backward partial differential equations for the distribution density of a random stopping point of the process are derived. The forward equation is investigated for the centrally symmetric case. Solutions of the equation demonstrate either a maximum or a local minimum at the source location. In the latter case a concentric ring around the source is formed. If different substances vary in their absorption rates, they can form separable concentration zones as a family of concentric rings.  相似文献   

15.
重力场定义的澄清   总被引:3,自引:1,他引:2  
曾华霖  万天丰 《地学前缘》2004,11(4):595-599
《朗曼现代英文词典》(LongmanModernEnglishDictionary)、《牛津高阶英汉双解词典》(OxfordAdvancedLearner’sEnglish ChineseDictionary)、《韦氏词典》(Merriam Webster’sNewCollegiateDictionary)、作为地球物理专业词汇定义源的《勘探地球物理百科词典》(EncyclopedicDictionaryofExplorationGeo physics)以及中国的一些重力教科书、专著及词典 ,把重力场定义为重力或重力作用存在的空间 ,重力效应可以测量的空间 ,即 :力或重力存在的空间。这个定义不同于国外英文地球物理教科书、专著及中、英、俄文场论教科书对重力场的定义 :空间中的重力。定义重力场为重力存在的空间 ,混淆了“场”本身及“场域”的概念 ,并不是一个标准的物理或地球物理定义 ,是一种误导。物理场是空间中存在的一种物理作用或效应 ,分布于引起它的场源体周围。两个物体之间存在着的相互作用力 ,通过每个物体引起的引力场给予另一个物体。重力场可以定义如下 :地球内部及其附近空间一点处存在的重力作用 ,或单位质量受到的重力。重力场是一种力或力场 ,存在于地球表面及其附近的空间。重力场不是空间 ,重力场的测量应当是在重力场存在的空间或场域中 ,而不是在重力场中进行。  相似文献   

16.
In this contribution we report a study of poorly exposed, rhyodacitic welded-ignimbrite deposit from Minas Gerais. A petrographic study of textures indicate high temperature of emplacement. Key features include eutaxitic texture, flattened and agglutinated lapilli and glass menisci. Most of the feldspar minerals and glass are extensively altered to clay minerals, which pseudomorph the original volcanic textures. Glass menisci and spherules suggest a possible process of liquid immiscibility. Immobile trace element distribution indicates a possible link with other post-Palaeozoic felsic volcanic rocks in Brazil, a magmatism interpreted as due to basaltic underplating and partial melting of a hydrous continental crust. A peculiar feature is a high Light REE/Heavy REE ratio. Depletion in heavy rare earth elements is possibly due to a residual HREE-bearing phase in the source. The geologic context of these rocks suggests a Lower Cretaceous age and a tectonic relationship with a continental rifting event.  相似文献   

17.
In this paper we present a study of the performance of sparse iterative solvers regarding the resolution of three-dimensional and non-linear problems encountered in soil/structure interaction. It is composed of two parts. In the first one, we present briefly iterative methods and preconditioners used in this study, then we analyse their performance on three soil/structure interaction problems: a shallow foundation under a vertical loading, a single pile subjected to a lateral loading and the construction of a lined tunnel in a soft soil. Tests are performed assuming an elastic–perfectly plastic constitutive law for the soil material with a non-associated Mohr–Coulomb flow rule. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   

18.
本文通过对在新疆南部塔里木盆地北缘博斯腾湖采集的一根953cm的岩心进行了早全新世以来的古气候重建。对BSTC2000岩心进行了碳酸盐矿物组成、Ca/1000Sr,有机质TOC,C/N和C/S分析,并结合BSTC2000岩心附近的一个沉积物剖面的孢粉资料,利用多指标重建了8500aBP以来的古气候变化特征。在2个平行岩心中对保存的植物叶片、草籽,以及全有机质进行了9个AMS14C年代测定。8500~8100aBP气候冷湿,钻孔位置为河流-滨湖相环境,沉积物中有3层泥炭层。从8100~6400aBP,气温升高,湖泊扩张,气候暖湿,湖泊可能为最高湖面时期。而从6400~5100aBP湖泊稍微下降,气候变冷。在中全新世晚期从5100~3100aBP气候变得高温干旱,但其间的4400~3800aBP有短暂的气候变冷,早期大量的冰雪融水补给博斯腾湖,使得湖泊水位上升。湖泊的第二个高湖面期是5200~3800aBP。在3100~2200aBP气候冷湿,由于蒸发减弱而湖泊有所扩张,湖泊在3100至2800aBP期间是最后一次短暂的高湖面期。这次短期高湖面后,湖泊由于较长时期的低温而引起的供水减少,湖泊收缩。从2200~1200aBP,气候变得干热,湖泊收缩。尽管从1200aBP以来,温度有所下降,气候变得暖干,湖泊又开始有所上升,但是没有达到博斯腾湖出水口孔雀河的海拔高度。  相似文献   

19.
南京汤山温泉区地热水成因模式分析   总被引:1,自引:0,他引:1       下载免费PDF全文
汤山温泉是中国四大著名温泉疗养胜地之一,阐明其成因模式对于该温泉区的进一步开发和热水资源的可持续利用具有一定意义。基于硅-焓图解法和水文地球化学方法对其进行了系统研究,结果表明该区热储温度为90℃,岩溶热水与岩溶冷水、孔隙潜水和地表水之间在水化学和同位素组成上存在明显差异,地热井深度越大,冷水混入相对较少,地热水温度相对较高。经分析,该地热系统成因上属于中低温对流型。其补给区主要来自汤山山体(宁镇山区)及句容盆地东侧茅山山脉,循环深度为2.6~2.9 km,地热水通过汤山-东昌街断裂在浅部与区内NW向断裂、NE向断裂交汇形成温泉水。  相似文献   

20.
Parama Roy 《Geoforum》2010,41(2):337-348
Arguments regarding citizen involvement and empowerment within neoliberal urban politics are ample in geographic literature. Existing discussions often define and evaluate empowerment as either some social, political, or economic end-product of a specific event. Such singular conceptualization is problematic. First, different kinds of social, political, and economic changes can simultaneously empower/disempower communities in contradictory ways. In addition, the view of empowerment as an end-product of a present event obscures a more nuanced understanding of empowerment as an ongoing process of state-civil society relation-building. An in-depth assessment of such a process is only possible with reference to the past and the potential future occurrences. Elwood’s (2002) multi-dimensional conceptualization of empowerment recognizes the limitations of a singular definition of empowerment. However, it falls short of operationalizing empowerment as a temporal process with a historically and geographically contingent past, dynamic present, and future in the making. Therefore, in this paper I expand on Elwood’s framework to show how a process-based view as opposed to a narrow end-product-based or event-based one can provide a deeper understanding of state-civil society interaction and community empowerment. This paper analyzes the interaction between the City of Milwaukee, the residents of a predominantly black inner-city neighborhood, the Walnut Way, and their community organization, the Walnut Way Conservation Corp. within a land-use dispute related to the development of a park space into a housing project. Using data collected through semi-structured in-depth interviews, archival research, and participant observation, this paper emphasizes that despite methodological limitations of collecting long-term data, community empowerment can and should be studied as a process with reference to the past, present, and potential future state-civil society interactions.  相似文献   

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