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1.
宁夏香山群徐家圈组发现深水复合流沉积构造 总被引：8，自引：1，他引：7
宁夏香山群徐家圈组是由灰绿、黄绿色轻微变质中—细粒砂岩、钙质砂岩及粉砂岩和页岩(板岩)组成的深水沉积。在上部灰绿色页岩所夹的中层钙质粉砂岩中发现了复合流层理、准平行层理、不对称小型丘状交错层理;在下部灰绿色厚层—块状中—细粒长石石英砂岩的顶面发现了小型波痕,波痕的形态、波长与波高的分布规律均表现出复合流(combined-flow)的沉积特征。本文根据水槽实验和现代海洋沉积观测所总结出的复合流底床相图和前人在研究地层中较浅海浊流(超重流)与波浪所形成的复合流沉积时给出的复合流沉积示意图,分别对徐家圈组所发现的①小型2D波痕至小型3D波痕的演化和②复合流层理、平行层理、准平行层理和小型丘状交错层理的叠置关系及其纹层所反映的流动方向与沉积时浊流方向的关系,进行了解释。结果表明,所发现的复合流层理、准平行层理、不对称小型丘状交错层理及小型波痕应为复合流沉积,并依据徐家圈组存在内波、内潮汐沉积的事实,推测为深水短周期内波与浊流形成的复合流沉积。这可能是地层中深水复合流沉积构造的首次发现,同时也是内波与浊流形成的复合流沉积的首次发现。 相似文献
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宁夏中奥陶统香山群为一套遭受轻微区域变质的陆源碎屑岩，并夹有少量碳酸盐岩和硅质岩，主要为深水浊流沉积。其中，徐家圈组主要由灰绿色、黄绿色轻变质细砂岩、钙质砂岩及粉砂岩和页岩组成，顶部发育有薄层石灰岩。在该组的中—薄层钙质粉—细砂岩、细粉屑质石灰岩和粉砂质页岩中发现了双向交错层理及纹层倾向与区域斜坡倾向相反或有较大夹角的单向交错层理，其中双向交错层理形态丰富、纹层清晰，其纹层倾向有沿斜坡向上的，有沿斜坡向下的。在深水环境中，这些交错层理不应是等深流沉积或浊流沉积的产物，而应为内波产生的沿斜坡上下水流交替流动所形成的。从沉积背景、沉积构造和古水流等方面对徐家圈组的内波、内潮汐沉积进行了详细的研究，认为其形成于水道不发育的深水斜坡环境，并对斜坡环境中内波、内潮汐沉积中不发育脉状、波状和透镜状层理的现象进行了解释。 相似文献
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贺兰山以南中奥陶统香山群徐家圈组古水流分析 总被引：11，自引：0，他引：11
贺兰山以南中奥陶统香山群为一套遭受轻微区域变质的陆源碎屑岩，并夹有少量碳酸盐岩和硅质岩，属于深海浊流沉积。其下部徐家圈组由灰绿、黄绿色轻变质细粒砂岩、钙质砂岩及粉砂岩和页岩组成，沉积环境为深水斜坡环境，并在该组发现了内波、内潮汐沉积，主要表现为双向交错层理。本文通过对徐家圈组指向沉积构造所显示的古水流资料进行研究，综合分析了香山群徐家圈组沉积时浊流方向和古斜坡方向，并利用古水流资料探讨了内波流和内潮汐流的方向。结果表明，槽模古水流方向从北向南略呈扇形发散状，代表了沉积时的浊流方向；交错层理古水流方向主要分散在NWW—NE之间，可以代表内波流和内潮汐流方向。对古水流平面分布特征进行综合分析，可以判断出沉积时区域斜坡方向与浊流方向基本一致，大致为SSW向，沉积时内波和内潮汐的传播方向则大致为NW向。 相似文献
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西秦岭古代地层记录中内波、内潮汐沉积及其成因解释 总被引：15，自引：2，他引：15
内波、内潮汐沉积是近十年来在古代深海环境中新发现的一种具牵引流性质的沉积相类型。西秦岭海西-印支造山带深海沉积中发现了多种样式的内波、内潮汐沉积,据沉积构造特征归纳为 7种微相类型 :1)具双向交错层细-中砂岩;2 )羽状交错纹理粉砂岩;3)束状透镜体叠加的交错纹理粉砂岩;4)复杂交织的双向交错纹理粉砂岩;5 )双向交错纹理粉砂岩;6 )波状、脉状和透镜状复合层理砂泥岩互层;7)波浪波痕细砂岩。研究表明,它们分别形成于 3种不同环境的深海浊流沉积体系内。内波、内潮汐沉积在深海环境中的分布特点 :一是具有普遍性;二是数量不够丰富;三是在层位上具有明显的选择性。通过研究说明,这些分布特点是与其形成和保存条件密切相关。 相似文献
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鄂尔多斯盆地南部地区延长组长7段主要发育以浊流及砂质碎屑流为主的深水重力流沉积。通过对盆地南部旬邑地区延长组长7段野外剖面露头进行详细考察时发现,该组砂岩中发育大量类似浅水环境的沉积构造,如交错层理、波状层理、平行层理、透镜状层理及波痕等。在综合研究区古构造、沉积背景的基础上,通过对野外露头进行详细的描述与刻画,认为盆地南部旬邑地区延长组长7段发育以等深流、内波、内潮汐为主要类型的深水牵引流沉积,上述类似浅水环境中的沉积构造为深水牵引流对先期形成的重力流沉积再作用的结果。总体上,研究区主要发育5种类型的深水牵引流岩相:(1)具双向交错层理粉细砂岩;(2)具单向交错层理粉砂岩;(3)具波状层理泥质粉砂岩、粉砂岩;(4)具平行层理细砂岩;(5)具大型交错层理中细砂岩。在此基础上探讨了研究区深水牵引流沉积模式。 相似文献
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贺兰山地区中奥陶统樱桃沟组深水牵引流沉积的发现及其意义 总被引：1，自引：0，他引：1
鄂尔多斯盆地西缘贺兰山地区的中奧陶统樱桃沟组发育一套夹有碳酸盐滑塌重力流沉积的陆源碎屑浊积岩,研究程度颇高。笔者在野外调查过程中于樱桃沟组浊流沉积体发育的环境中发现了相当数量的交错层理,如大型交错层理,板状交错层理,波状、脉状、透镜状层理和波痕等,曾一度被前人解释为浅水沉积环境的识别标志。本文结合当时的古地理背景、沉积环境和区域构造演化特征,通过对樱桃沟组野外露头的详细描述和岩石特征的精细刻画以及对该组沉积序列的详细分析,认为上述疑似浅水沉积环境的交错层理实为底流(深水牵引流)对浊流改造的结果,并分别形成了内波、内潮汐沉积和等深流沉积,这在研究区为首次发现。据此将其归纳为7种岩石类型:(1)双向交错层理粉砂岩;(2)束状透镜体叠加的交错纹理粉砂岩;(3)具波状层理粉砂岩;(4)单向交错层理砂岩;(5)水流波痕细砂岩;(6)平行层理细-中砂岩;(7)大型交错层理细砂岩。其中,前5种岩石类型为内波、内潮汐沉积,后两种为等深流沉积。研究表明樱桃沟组为深水牵引流沉积(内波、内潮汐沉积、等深流沉积)、重力流沉积(碳酸盐滑塌角砾岩、浊积岩)和原地沉积的复合沉积,并建立了该区水道型内波、内潮汐沉积模式。 相似文献
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在南祁连西段清水沟南广泛分布着一套深色碎屑沉积岩系,经区域对比划归为巴龙贡噶尔组,其时代定为早志留世。该组岩石由细砂岩类—粉砂岩类—泥岩类(已变质成千枚岩岩类)组成,砂岩层中见有粒序层理、交错层理,发育水平纹理。细砂岩、粉砂岩中杂基含量高达25%～45%,指示浊流沉积特点,岩石中发育不完整的鲍马层序。该组岩石沉积构造、基本层序、粒度曲线、微量元素、稀土元素特征都反映出该组形成于海底扇区,浊积岩与深海泥岩以不同比例随机重复组合构成复理石沉积建造。 相似文献
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本文详细论述了赣西北前寒武系首次发现的深水牵引流内波内潮汐沉积特征的沉积构造、岩石组合和沉积序列。沉积构造主要发育双向和单向交错层理、曲线型和干涉波痕及波状、脉状、透镜状层理;常产于深水重力流之上或与之共生。岩石粒度结构特征为明显的牵引流性质。共划分出双向交错层理砂岩组合,单向交错层理砂岩组合,薄层砂岩——板岩组合和波状、脉状、透镜状细砂岩——粉砂岩——板岩组合;可识别出双向递变、单向递变和对偶层递变序列。在综合研究和分析的基础上,进一步阐述了内波内潮汐沉积与浊流沉积的异同点和相互关系以及内波内潮汐沉积的保存条件、沉积环境和控制机理。深水牵引流内波内潮汐沉积学特征的系统研究,对正确阐明沉积盆地的大地构造背景及形成演化具有重要意义。 相似文献
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在南祁连清水沟一带,盐池湾组呈北西西-南东东向展布．为一套深灰绿色细碎屑浊积岩系夹深海泥岩。主要岩性有变泥质粉砂岩、长石石英杂砂岩、细砂质长石石英粉砂岩、长石杂砂岩、绢云石英千枚岩等。岩石中粒序层理、交错层理不太发育,指示该组岩层层序是倒转的．即北老南新。该组发育不完整鲍玛层序,有3种类型．即ABCD型、韵律型和均一型。综合研究盐池湾组的宏观岩性特征、基本层序、沉积构造、浊流沉积岩石学特征、粒度曲线特征、微量元素、稀土元素指数等蕴藏在沉积岩中的各种地质信息,指示该组形成于次深海至深海相浊流沉积中端相和远端相区。浊积岩与深海泥岩以不同比例重复组合,构成复理石沉积建造。 相似文献
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鄂尔多斯盆地西缘奥陶系拉什仲组发育一套砂泥互层的深水重力流沉积,其下部重力流复合水道发育。综合野外实测、薄片和粒度分析等,探讨复合水道沉积特征、形成过程及主控因素,最终建立其沉积模式。结果表明：(1)研究区发育5种岩相和3种岩相组合,即块状层理砾屑灰岩相(Cm)、粒序层理细—粉砂岩相(Sg)、平行层理砂岩相(Sp)、交错层理粉砂岩相(Sc)、水平层理(泥)页岩相(Sh),分别代表碎屑流沉积(Cm)、浊流沉积(Sg, Sp, Sc)及深水原地沉积(Sh);(2)根据复合水道内部单一水道形态、岩相组合及粒度等将复合水道分为4个期次,反映重力流能量由强到弱的变化过程;(3)复合水道多期次发育与相对海平面升降、沉积物供给、构造运动和重力流规模及能量变化密切相关;(4)重力流沉积为斜坡—盆地环境中复合水道沉积模式。该研究可补充对研究区重力流水道认识,为油气勘探提供借鉴。 相似文献
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S. Viswanathan K. Surya Prakash Rao B. Mahabaleswar 《Journal of the Geological Society of India》2013,82(6):621-627
Komatiites are mantle-derived ultramafic volcanic rocks. Komatiites have been discovered in several States of India, notably in Karnataka. Studies on the distribution of trace-elements in the komatiites of India are very few. This paper proposes a simple, accurate, precise, rapid, and non-destructive wavelength-dispersive x-ray fluorescence (WDXRF) spectrometric technique for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in komatiites, and discusses the accuracy, precision, limits of detection, x-ray spectral-line interferences, inter-element effects, speed, advantages, and limitations of the technique. The accuracy of the technique is excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr, Nb, Ba, Pb, and Th and very good (within 4%) for Y. The precision is also excellent (within 3%) for Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th. The limits of detection are: 1 ppm for Sc and V; 2 ppm for Cr, Co, and Ni; 3 ppm for Cu, Zn, Rb, and Sr; 4 ppm for Y and Zr; 6 ppm for Nb; 10 ppm for Ba; 13 ppm for Pb; and 14 ppm for Th. The time taken for determining Sc, V, Cr, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, Pb, and Th in a batch of 24 samples of komatiites, for a replication of four analyses per sample, by one operator, using a manual WDXRF spectrometer, is only 60 hours. 相似文献
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E. M. Prasolov S. A. Sergeev B. V. Belyatsky E. S. Bogomolov K. A. Gruzdov I. N. Kapitonov R. Sh. Krymsky V. O. Khalenev 《Geochemistry International》2018,56(1):46-64
This paper reports the first results of a study of 11 isotope systems (3He/4He, 40Ar/36Ar, 34S/32S, 65Cu/63Cu, 62Ni/60Ni, 87Sr/86Sr, 143Nd/144Nd, 206–208Pb/204Pb, Hf–Nd, U–Pb, and Re–Os) in the rocks and ores of the Cu–Ni–PGE deposits of the Norilsk ore district. Almost all the results were obtained at the Center of Isotopic Research of the Karpinskii All-Russia Research Institute of Geology. The use of a number of independent genetic isotopic signatures and comprehensive isotopic knowledge provided a methodic basis for the interpretation of approximately 5000 isotopic analyses of various elements. The presence of materials from two sources, crust and mantle, was detected in the composition of the rocks and ores. The contribution of the crustal source is especially significant in the paleofluids (gas–liquid microinclusions) of the ore-forming medium. Crustal solutions were probably a transport medium during ore formation. Air argon is dominant in the ores, which indicates a connection between the paleofluids and the atmosphere. This suggests intense groundwater circulation during the crystallization of ore minerals. The age of the rocks and ores of the Norilsk deposits was determined. The stage of orebody formation is restricted to a narrow age interval of 250 ± 10 Ma. An isotopic criterion was proposed for the ore-bearing potential of mafic intrusions in the Norilsk–Taimyr region. It includes several interrelated isotopic ratios of various elements: He, Ar, S, and others. 相似文献
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奥地利安东帕有限公司 《岩矿测试》2009,28(3):306-306
最新的流行病学研究表明,空气中较高浓度的悬浮细颗粒可能对人类的健康有不利的影响。根据该项研究显示,由于心脏病、慢性呼吸问题和肺功能指标恶化而导致死亡率的升高与细尘粒子有关。这些研究结果已经促使欧盟于1999年4月出台了限制空气中二氧化硫、二氧化氮、氧化氮、铅和颗粒物含量的法案(1999/30/EC),对各项指标包括对可吸入PM10颗粒的浓度提出了新的限制性指标。PM10颗粒是指可以通过预分级器分离采集的气体动力学直径小于10μm的细颗粒。目前研究的兴趣重点逐步偏向PM2.5这些更细微颗粒物,PM2.5这种颗粒物对健康有明显的不利影响。在欧盟指令2008/50/EC中,对PM10和PM2.5都提 相似文献
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Mining induced subsidence can significantly affect mining costs where major surface facilities and natural environment need to be protected. Overburden grout injection is a technology used to control coal mine subsidence by injecting the mine waste material extracted from the coal back into the inter-burden rock during longwall mining. The flowing slurry is here categorised as a nonlinear viscous cohesive (Bingham plastic) fluid. During longwall mining the grout slurry is pumped into the separated beds of the rock mass through a central vertical borehole, which is drilled deep into the inter-burden rock strata above the coal seam. However, a blockage can occur in the injection system when the slurry velocity falls below a certain critical threshold velocity, indicating a material phase change from cohesive-viscous to cohesive-frictional. In situ field injection tests through boreholes have been simulated at a smaller scale at the CSIRO laboratory in Brisbane by pumping the slurry through a radial disk (gap = 4 mm) from its centre. Laboratory experiments indicate a general, nonlinear, cohesive, viscous, frictional model for shear behaviour of the slurry, in which the material shear parameters are functions of the disk radial distance. Complete dimensional and dimensionless analytical solutions have been developed based on an approach related to Bingham–Herschel–Bulkley fluid mechanics. The derived formulae include relations for minimum pump pressure, local pressure and pressure gradient, wall shear stress, volume rate, velocity and velocity gradient. The theoretical results match the experimental measurements. The experiments covered slurries with maximum particle sizes of 0.5 to 2 mm with about 50% being larger than 100 µm. The viscosities at the various solids concentrations were measured with a standard torsion viscometer. This study differs from the previous research in several distinct aspects, namely, consideration of the variable shear parameters rather than fixed values, inclusion of total nonlinear behaviour, and implementation of a friction function to mimic behaviour of the deposited and consolidating stiff slurry, which can cause a significant pressure rise as a result of the increased shear resistance. 相似文献
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Alexander E. C. Broberg J. S. Kehren A. R. Graziani M. M. Turri W. L. 《Environmental Geology》1993,22(4):353-361
Bellechester, Minnesota, is a small community of approximately 155 residents located on the county line between Goodhue and Wabasha counties in southeast Minnesota's karst region. Bellechester is served by a 21-year-old wastewater treatment facility (WWTF) consisting of three waste-stabilization ponds. On 28 April 1992 six sinkholes were discovered to have drained cell 2 of the WWTF resulting in the loss of approximately 8.7×106 1 of partially treated effluent and about 600 m3 of soil into previously undetected subsurface voids of unknown dimensions. In the week following the collapse, approximately 200 water wells located within a 5-km radius of the WWTF were sampled in an after-the-fact, emergency sampling program. Twelve samples with elevated fecal coliform levels, 18 samples with nitrate-nitrogen greater than the 10 mg/1 standard, and no samples with elevated chlorides were found. However, the elevated levels could not be unambiguously attributed to the WWTF collapse. This is the third WWTF to fail by sinkhole collapse in southeast Minnesota since 1974. All three collapsed lagoons have been located in similar geomorphic and stratigraphic settings. However, at least two lagoons have collapsed in the adjacent area in northeast Iowa, and these lagoons are located at different stratigraphic positions. Twenty-two WWTFs constructed in southeast Minnesota's karst region in the last 25 years have been identified as subject to potential sinkhole collapse. An unknown but significant number of manure storage lagoons, flood control structures, etc., have also been constructed in the karst region and are at risk. Public agencies are beginning to develop plans to deal with the risk associated with existing and future waste lagoons in this environment. The critical hydrogeologic parameters that can be used to prioritize the risk of collapse at existing facilities include: (1) the lithology of the first bedrock beneath each lagoon, (2) the thickness of surficial materials between the lagoon and the bedrock surface, (3) the presence and construction of liners (seepage rate), and (4) the proximity to existing sinkholes. 相似文献
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岩石密度和超高压岩石折返速率 总被引：1，自引：3，他引：1
在常温常压条件下对中国大陆科学钻CCSD主孔100-3000米岩心样品进行了密度测量,建立了密度连续剖面,并界定了不同超高压岩石的密度值。通过对比高温高压物性实验资料,岩石密度随着退变程度增强而降低,榴辉岩密度变化序列为3.52g/cm3→3.49g/cm3→3.07g/cm3→2.93g/cm3。超高压长英质岩石密度变化序列为3.00g/cm→2.80g/cm3→2.65g/cm3。上述实验资料是讨论不同折返阶段岩石所受浮力的基础,为研究折返速率大小提供了基本参数。本文通过折返板块运动平衡时,上浮力与粘滞力平衡这一关系式,定量研究了大陆俯冲板块的折返速率,认为密度差产生上浮力从而引起折返,温度对板块折返速率的影响最为显著;密度差大小、折返角度、折返板块大小对折返速率也有直接的影响。定量模拟分析表明,在温度高于850℃时,板块的折返速率可以超过100mm/a;当温度降至700℃时,折返速率则低于1.5mm/a。作者认为在折返早期,温度较高,板块快速折返至60-70km榴辉岩相深度;随着传导散热,温度降低,板块以较慢的速率折返至中下地壳。折返速率的估算表明,浮力是板块折返第一阶段(从>100km深部折返至<40km的中下地壳)的主要驱动力。 相似文献
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Mercury,arsenic, antimony,and selenium contents of sediment from the Kuskokwim River,Bethel, Alaska,USA 总被引：1，自引：0，他引：1
The Kuskokwim River at Bethel, Alaska, drains a major mercury-antimony metallogenic province in its upper reaches and tributaries. Bethel (population 4000) is situated on the Kuskokwim floodplain and also draws its water supply from wells located in river-deposited sediment. A boring through overbank and floodplain sediment has provided material to establish a baseline datum for sediment-hosted heavy metals. Mercury (total), arsenic, antimony, and selenium contents were determined; aluminum was also determined and used as normalizing factor. The contents of the heavy metals were relatively constant with depth and do not reflect any potential enrichment from upstream contaminant sources. 相似文献