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1.
小场院磷矿含矿层位为下寒武统渔户村组,胶磷矿由砂屑、砾屑、鲕粒组成,孔隙式、孔隙—基底胶结,铁泥质胶结,颗粒形态显次圆—不规则状,粗颗粒含量显著增高;沉积环境处于古陆边缘浅海域,推测沉积的矿物质来源主要取决于古陆风化淋滤作用. 相似文献
2.
云南昆阳、海口磷矿的富集机理 总被引：3，自引：0，他引：3
本文阐明滇东早寒武世昆阳、海口磷矿沉积于牛首山古陆及滇中古陆之间的海湾泻湖环境,有利于两侧的深海槽盆洋流上升,可以将分散磷质不断带到浅水海湾之中;具有高本底值磷质的古陆,由于迳流也提供一定的磷质;由于磷质及其它生命元素源源不断供给,使得温暖、浅水海湾的菌、藻生物大量繁殖,有效地固定了海水中分散的磷质并沉聚于海湾底部沉积物中。昆阳磷矿与海口磷矿之间近东西向水下隆起的存在,从搅动的浅水产生磷质沉积物的簸选,导致较粗的颗粒磷块岩的富集。经过早期成岩阶段的酶、菌作用,使孔隙水中磷质聚集形成胶结物,进一步使颗粒磷块岩品位更富。 相似文献
3.
汉中地区磷矿主要为早寒武世梅树村期及晚震旦世陡山沱期产物，以前者为主。矿床围绕古陆（特别是摩天岭和汉南古陆）边缘分布，为浅海 滨海相沉积产物。磷质物源主要来自古陆，而海底火山活动提供的Ｐ、Ｍｇ、Ｆ成为天台山磷矿形成的重要物源。摩天岭及汉南古陆边缘具有良好的找矿前景。 相似文献
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四川雷波地区寒武系下统麦地坪组岩层普遍有磷矿层产出,勘查成果显示,该磷矿层稳定,品位高,规模大,为古陆边缘浅深海-半封闭滞流海湾相生物化学沉积型磷矿床。通过雷波马颈子—牛牛寨地区磷矿床成矿地质背景介绍,指出了该区磷矿具有良好的找矿远景。 相似文献
6.
黔中开阳地区在震旦纪陡山沱期全球成磷事件的大背景下,发育了厚度较大的富磷矿层。通过岩石薄片观察、地层对比与划分及沉积相分析等手段,探讨黔中开阳地区震旦纪陡山沱期磷矿床沉积特征与成矿模式。结果表明:(1)开阳地区陡山沱期处于黔中古陆北缘的磷质海岸环境,磷矿层中分布最广泛、品位最高的矿石类型为砂屑磷块岩,为富磷沉积物在沉积、成岩过程中遭受多期次冲刷破碎、暴露淋滤及堆积胶结的产物。(2)开阳地区古地理环境和动荡的海水条件控制了磷矿的沉积和高品位矿石的分布,洋水、永温等地在震旦纪陡山沱期所处的海水深度适中的临滨带为成矿优势地带,而水体过浅的前滨带和过深的远滨带均不利于磷质的聚集和成矿。(3)开阳地区动态磷矿床成矿模式表明,陡山沱期海平面的频繁进退使临滨带已沉积的磷块岩遭受多期次的冲蚀、暴露、淋滤、胶结及磷质再沉积作用;通过物理分选作用和风化淋滤作用最终使磷质聚集,是研究区富磷矿形成的主要原因。 相似文献
7.
<正> 白塔村磷矿是云南省已探明的大型磷块岩矿床之一。地处“康滇古陆”东缘,昆明凹陷西侧,香条冲背斜之比冀。磷矿层赋存于下寒武统渔户村组中。共见两层矿,分别称上层矿和下层矿。本文着重讨论磷块岩矿石的磷酸盐矿物种属及磷矿物的形态类型等方面问题。组成磷块岩的磷酸盐矿物多为隐晶质,颗粒极细小,长期以来,把这些隐晶质钙磷酸盐矿物笼统称为“胶磷矿”,这一命名並不准确。因此,对磷块岩中磷酸盐矿物做进一步的研究,对探讨成矿理论及指导选矿工作,都具有实际意义。 相似文献
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苏北盆地金湖凹陷腰滩地区古近系阜宁组储层物性特征及其影响因素 总被引：2，自引：1，他引：1
苏北盆地金湖凹陷腰滩地区古近系阜宁组储层岩石类型以岩屑长石砂岩和长石砂岩为主,其成分成熟度中等,结构
成熟度中等到好。腰滩地区储层成岩作用主要包括压实、胶结、溶蚀和交代四种类型, 目前处于晚成岩阶段A期。研究区储
层的储集物性受成岩作用和构造运动的共同影响,主要表现为对孔隙度和渗透率的影响, 其中压实和胶结作用使储层原生
孔隙迅速减少、渗透率降低、储集物性变差,而溶解作用则是导致次生孔隙发育及改善砂岩储集性能的主要因素。压实作
用主要表现为刚性颗粒发生脆性破裂、塑性颗粒挤压变形或刚性颗粒嵌入塑性颗粒中、颗粒之间呈线接触和凹凸接触、碎
屑颗粒呈明显的定向排列等; 溶蚀作用表现为碳酸盐矿物的溶解; 胶结物主要为自生黏土矿物、碳酸盐和自生石英。交代作
用主要为碳酸盐胶结物交代石英、长石及岩屑颗粒及碳酸盐胶结物之间的相互交代等。构造运动使局部的储层物性得到改
善。 相似文献
10.
云南省永善县务基磷矿赋存于下寒武统梅树村组中谊村段地层中,矿石矿物以胶磷灰石为主,具砂屑、砾屑及鲕粒结构,薄-中层状、块状及条纹条带状构造,矿石自然类型为砾屑状磷块岩、条纹状白云质磷块岩、条带状白云质磷块岩、硅质磷块岩。通过分析矿区所处古构造、古地理特征和矿石结构特征,认为务基矿区磷矿为浅海相沉积磷块岩矿床。 相似文献
11.
芒亨河断裂的次级断裂是主要控矿构造,含矿围岩为上三叠统小定西组(T3xd)富钠质安山岩、玄武岩。受构造、层位、碎屑粒度的制约。 相似文献
12.
胶磷矿的矿物组成,主要是微碳—低碳磷灰石,及细晶磷灰石。而胶磷矿细微颗粒,经电镜观察鉴定,主要由磷酸盐化有机碎屑及藻席碎屑组成,早寒武世磷块岩的形成是生物学、沉积学、古地理—古构造等综合因素沉积作用的产物。 相似文献
13.
江西大背坞地区浅变质岩中同生碎屑的发现及其地质意义 总被引：5，自引：0，他引：5
同生碎屑是沉积岩中一种反映动荡沉积环境的典型构造现象。笔者在大背坞地区首次发现了同生碎屑，这对确定双桥山群属于浊流相沉积提供了又一重要证据。根据同生碎屑的变形特征，笔者认为本区双桥山群地层主要经历两期变形，即以压扁为主的区域褶皱变形和以剪切为主的韧性剪切变形。 相似文献
14.
Matthew R. Bennett Richard I. Waller Neil F. Glasser Michael J. Hambrey David Huddart 《第四纪科学杂志》1999,14(2):125-135
The interpretation of glacigenic diamictons is a subjective process, for which quantitative support is frequently sought from parameters such as clast shape and fabric. It has been widely suggested that different glacigenic diamicton facies possess distinct clast‐fabric signatures. This paper examines this concept using a data set of 111 clast fabrics, and a synthesis of published results. Eigenvalues are calculated and compared for a variety sedimentary facies. It is concluded that clast fabric alone is not able to discriminate between different glacigenic facies, and it is argued that clast fabric offers little quantitative support in the interpretation of glacigenic sediments. It is suggested, therefore, that although clast fabric may continue to have a role as an indicator of relative strain at specific sites, its use in the discrimination of glacigenic facies is limited. Consequently, we should be much more selective in undertaking such analyses in the future. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
15.
攀西的结晶基底岩系——康定群,褶皱基底岩系——会理群、昆阳群与北澳大利亚地区一致,是泛冈瓦纳大陆的组成部分。泥盆—二叠纪时期,扬予古陆发生强烈地裂运动,后期扬予古陆向北漂移,导致了它与澳大利亚的分裂,这时攀西不再是一个单纯的内陆裂谷,它发展为原大洋,成为扬予古陆西缘的被动大陆边缘裂谷。二叠纪末它可能与同步向北漂移的羌塘-印支古陆拼合:三叠纪初与华北陆块拼合;于侏罗纪、白垩纪分别与藏北及藏南陆块拼合;喜马拉雅运动,印度板块碰撞,形成了统一的亚洲大陆,本区受造山作用影响,形成广泛的冲断-推覆体构造形体。 相似文献
16.
南海北部深水西区中中新世混合沉积模式及控制因素 总被引：1，自引：0，他引：1
以新采集的地震资料为基础,对南海北部深水西区的混合沉积作了初步研究。混合沉积在地震剖面上表现为平行—亚平行,振幅强—中,频率中等及连续性中等的反射特征。混合沉积分布在研究区地震资料覆盖范围的西北角,发育规模较大,最大长度达44.7km,最大宽度33.2km,面积1084km2,最大厚度为138m,纵向上分布在中中新统梅山组。综合南海北部构造演化、地震勘探等研究成果,建立了混合沉积模式。该混合沉积分布于半深海沉积区,由其南东东方向的西沙—广乐台地提供碳酸盐岩碎屑(同时也提供部分硅质碎屑),由其西侧的中南半岛提供主要的硅质碎屑。在南海北部深水西区,控制混合沉积分布的主要因素为构造作用(包括海平面变化)、物源供给及水动力条件等三个方面,这三者之间又具有密切的内在联系。 相似文献
17.
Although analysis of clast macrofabrics has been used to differentiate between different types of glacial diamictons and to determine palaeo‐ice flow directions, no account appears to have been made of preferred clast orientations inherited from the parental source material. Clast macrofabrics in tills are typically interpreted as having developed in response to an imposed subglacial deformation and as such provide a link between the sedimentary record and glacier dynamics. They rely on the assumption that any preferred clast orientation is a result of deformation/flow. The results of the micromorphological study of the Langholm Till exposed at North Corbelly near Dumfries (southwestern Scotland) clearly demonstrate that bedrock structure can influence clast orientation (macrofabric) within diamictons. In the lower part of the till, the orientation of elongate clasts preserves the geometry of the tectonic cleavage present within the underlying bedrock. The intensity of this steeply inclined, ‘inherited’ clast fabric decreases upward through the till, to be replaced by a more complex pattern of successive generations of clast microfabrics developed in response to deformation/flow. These results indicate potential limitations of applying clast macrofabric or microfabric analysis in isolation to establish till genesis or palaeo ice‐flow directions. Consequently, due account should be made of other glacial palaeo‐environmental and ice flow indicators, as well as rockhead depth and morphology in relation to the selection of fabric measurements sites. © British Geological Survey/Natural Environment Research Council copyright 2007. Reproduced with the permission of BGS/NERC. Published by John Wiley & Sons, Ltd. 相似文献
18.
Glenn J. MacPherson David W. Mittlefehldt Michael E. Lipschutz Robert N. Clayton Emma S. Bullock Andrei V. Ivanov Toshiko K. Mayeda Ming-Sheng Wang 《Geochimica et cosmochimica acta》2009,73(18):5493-5511
Oxygen isotope and trace element data for 13 samples of the Kaidun chondritic breccia reaffirm the complex polymict nature of this unique meteorite. Bulk Kaidun samples most closely resemble CR chondrites, but the matrix is CI-like. Two separated clasts are CR-like but have some properties that resemble CM, two clasts are enstatite chondrites (one EL and one EH), one clast is an aubrite-like metal-rich impact melt, and one clast is a unique layered olivine-bearing pyroxenite with the isotopic composition of an aubrite. Yet, although each clast resembles a known meteorite group, all deviate in some respect from the norms for those groups. Collectively, Kaidun has sampled materials not yet represented in the world meteorite collections and which greatly extend the definitions of known meteorite groups. Phyllosilicates in Kaidun span a very wide range in composition and vary from clast to clast, suggesting that the aqueous alteration experienced by the clasts predated assembly of the Kaidun parent body. 相似文献
19.
<正> 科学领域中的任何一门学科在其发展的历史中,往往存在着以具有重大突破为标志的迅速发展阶段。板块构造学说就是现代地球科学取得最新进展的代表。所以,有人将其称为地球科学的一场革命。板块构造理论创建于六十年代后期,但与其有关的一些思想、概念则源远流长。 相似文献
20.
JOHN A. MATTHEWS 《Boreas: An International Journal of Quaternary Research》1987,16(2):173-188
Matthews, John A. 1987 06 01: Regional variation in the composition of Neoglacial end moraines. Jotunheimen, Norway: an altitudinal gradient in clast roundness and its possible palaeoclimatic significance Boreas , Vol. 16, pp. 173–188. Oslo. ISSN 0300–9483.
Quantitative indices of clast roundness from Neoglacial end moraines in front of 81 Jotunheimen glaciers were compared and analysed. Statistical techniques, including non-metric multidimensional scaling, multiple regression and partial correlation, were used to relate clast roundness to selected environmental variables. Three independent variables – site altitude, glacier length (interchangeable with height of headwall relative to glacier length) and aspect – cumulatively accounted for about 58% of the variability in clast roundness. A climatic factor complex (represented by altitude and aspect) was found more important than morphological factors (such as glacier size and headwall size) in accounting for clast roundness variations between glaciers. The scale of the independent effects of altitude, morphology, aspect and geology was found in the approximate proportions 4:1.5:1:1. Several theoretical mechanisms are proposed which could explain a causal relationship between climate and clast roundness by influencing the relative importance of supraglacial and subglacial debris supply. The palaeoclimatic implications of the results are discussed with particular reference to the prediction of mean annual temperatures from clast roundness; one unit increase in clast roundness corresponding to an increase in mean annual temperature of about 1.4°C within the study area. 相似文献
Quantitative indices of clast roundness from Neoglacial end moraines in front of 81 Jotunheimen glaciers were compared and analysed. Statistical techniques, including non-metric multidimensional scaling, multiple regression and partial correlation, were used to relate clast roundness to selected environmental variables. Three independent variables – site altitude, glacier length (interchangeable with height of headwall relative to glacier length) and aspect – cumulatively accounted for about 58% of the variability in clast roundness. A climatic factor complex (represented by altitude and aspect) was found more important than morphological factors (such as glacier size and headwall size) in accounting for clast roundness variations between glaciers. The scale of the independent effects of altitude, morphology, aspect and geology was found in the approximate proportions 4:1.5:1:1. Several theoretical mechanisms are proposed which could explain a causal relationship between climate and clast roundness by influencing the relative importance of supraglacial and subglacial debris supply. The palaeoclimatic implications of the results are discussed with particular reference to the prediction of mean annual temperatures from clast roundness; one unit increase in clast roundness corresponding to an increase in mean annual temperature of about 1.4°C within the study area. 相似文献