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1.
《新疆地质》2017,(3)
碳酸盐岩碳、氧同位素对古气候、古环境及成岩流体示踪具重要的指示意义。通过对羌塘盆地南部昂达尔错地区QZ-11井、QZ-12井布曲组岩心观察、薄片鉴定及碳氧同位素分析,结果表明:研究区布曲组是在炎热、半干旱-半潮湿古气候条件下,在台地边缘礁滩环境发育的一套碳酸盐岩沉积;岩性包括灰岩,白云岩及过渡性岩类,白云岩主要发育在高位体系域晚期台缘浅滩微相中,白云岩包括保留先驱灰岩原始组构的颗粒白云岩、泥微晶白云岩及先驱灰岩原始组构不可见的晶粒白云岩;研究区内的碳酸盐岩δ~(13)C_(PDB)分布范围为1.5‰~4‰,δ18OPDB分布范围为-7.6‰~-12.1‰,其中灰岩的δ~(13)C_(PDB)分布范围为1.5‰~2.9‰,普遍高于同期全球海水碳同位素值,推测可能与高位体系域晚期强蒸发及生物繁盛有关,白云岩和过渡性岩类中δ~(13)C_(PDB)分布范围为1.4‰~4‰,说明为继承先驱灰岩中碳同位素组成,局部可能受到白云石化流体的改造;氧同位素组成虽然普遍低于同期海水值,但白云岩中保留先驱灰岩原始组构的颗粒白云岩氧同位素值仍高于灰岩,表明其形成与蒸发环境有关,而细晶白云岩、中粗晶白云岩氧同位素组成呈逐步降低趋势,表明可能受埋藏阶段温度升高的影响。 相似文献
2.
新疆乌鲁木齐地区红雁池南剖面中二叠统芦草沟组主要发育浅湖至半深湖背景下的中、薄层深灰色白云岩、灰岩、粉砂岩与中、厚层灰黑色页岩、泥岩互层。白云岩主要由泥晶白云石、铁白云石及少量方解石、高镁方解石组成,富含有机质。白云石粒径约3～10 μm,阴极发光呈现均匀昏暗的砖红色。白云石主要有微球状（直径约5～8 μm）、微簇状（长度约2 μm）及他形（1～10 μm）等3种微形貌。微球状白云石具有显微纹层结构,似为生长纹层,放大至6万倍发现显微纹层是由无数纳米级颗粒构成。他形白云石放大至4万倍发现主要由大量直径约0.25 μm的球状微粒聚集粘结而成,具有微生物矿化的特征。将研究区白云石与现代典型微生物成因白云石相比,其显微形态特征非常相似。研究区白云岩δ13CPDB为1.8‰～13.8‰,δ18OPDB为-12.1‰～-4.1‰,偏高的δ13C可能是产甲烷菌活动引起有机质碳同位素分馏的结果。以上特征表明,芦草沟组具有特殊形貌白云石的沉淀很可能与厌氧微生物密切相关。 相似文献
3.
《古地理学报》2020,(1)
准噶尔盆地东部吉木萨尔凹陷中二叠统芦草沟组,沉积于陆内裂谷背景下岩浆—热液活动强烈的咸化湖盆中。在芦草沟组中发现一类与湖底热液活动有关的幔源热液沉积白云岩,包括方沸钠长白云岩、硅质白云岩与含水铵长石钠长白云岩。作者对该类白云岩开展微米级尺度的岩相学研究,结合同位素地球化学研究,探讨成矿流体性质与详细成因机理。岩矿特征和同沉积变形构造指示白云岩形成于沉积期。白云石为有序性较差的原白云石,呈微米级球状、葡萄状晶体,与方沸石、水铵长石、钠长石及玉髓等热液矿物彼此镶嵌结晶,高温下发生了白云石对钠长石碎屑的交代作用;白云岩锶同位素(平均为0. 705 687)显示成矿流体中幔源组分较多;白云岩具有重δ13CPDB(平均为6. 94‰)和轻δ18OPDB(平均为-8. 12‰)。基于成矿流体由幔源热液与湖水混合的假设,利用δ18OPDB计算估计,研究区白云岩的形成温度较普通云质岩高25～50℃。研究表明白云石为幔源热液喷出湖底后直接沉淀形成,并提出可能的成因模式。热液沉积白云岩是一种不可或缺的白云岩成因类型,研究成果对促进人们理解白云石的形成规律、推动完善成因岩石学理论具有重要意义。 相似文献
4.
咸化湖盆白云岩碳氧同位素特征及古环境意义:以柴西地区始新统下干柴沟组为例 总被引：4，自引：0，他引：4
近年来,柴西地区始新统致密碳酸盐岩中的油气勘探获得了重要进展,其中白云岩为最优质的储集岩。系统的岩石学、矿物学和地球化学特征研究表明,该套白云岩主要为泥晶结构,白云石晶间孔广泛发育,孔径多小于1μm。泥晶白云岩的δ13CPDB值变化范围为-4.5‰~0.2‰,平均值为-2.4‰,相对于典型湖相碳酸盐岩偏负,反映了周缘辫状三角洲供给富含轻碳的地表水在一定程度上改变了白云岩的碳同位素组成,且湖水中的溶解碳部分来源于有机质氧化解体产生的CO2,通过改变湖水中溶解碳的碳同位素组成从而间接影响了湖相白云岩的碳同位素组成。泥晶白云岩的δ18OPDB值变化范围为-6.1‰~0.4‰,平均值为-2.6‰,相对于典型湖相碳酸盐岩偏正,明显受咸化湖沉积环境影响。碳氧同位素相关关系投点图及其计算出的盐度、温度数据反映了泥晶白云岩是在准同生阶段、半开放-半封闭的咸化环境下、于水/沉积物界面附近由方解石交代而成的低温白云岩,这类准同生交代成因白云岩在区域上分布较广,且孔径极小的白云石晶间孔抗压实能力强,这一重要发现无论是平面展布上还是纵向深度上均开拓了柴达木盆地致密油勘探的新领域。 相似文献
5.
白云鄂博赋矿白云岩与微晶丘和碳酸岩墙的碳氧同位素对比研究 总被引：26，自引：7，他引：19
本文通过方解石和白云石的碳和氧同位素分析,对比研究了白云鄂博赋矿白云岩、黑脑包微晶丘、北京西山微晶丘、宽沟北正常沉积灰岩和白云鄂博碳酸岩墙,从而探讨了赋矿白云岩的成因及其与超大型Fe-Nb-REE矿床的成因关系。结果为:①黑脑包腮林忽洞群顶部微晶丘和北京西山寒武系顶部微晶丘碳酸盐的δ~(13)C值都在0±2‰左右,δ~(18)O值为18.3‰～25.1‰,均具有典型海相沉积碳酸盐岩的特点;②白云鄂博东矿采场δ~(13)C值为-7.9‰～-1.1‰,δ~(18)O值为9.1‰～20.9‰;矿区东西两端δ~(13)C值-7.9‰～-0.6‰,δ~(18)O值8.6‰～25.7‰;均介于地幔流体与典型沉积碳酸盐岩之间。部分赋矿白云岩样品中白云石与方解石之间的碳氧同位素分馏△~(13)C和△~(18)O值均小于0‰,表明其受到过次生蚀变作用,低δ~(18)O值白云石样品所对应的负△~(18)O值反映了地幔镁质流体对沉积碳酸盐岩的强烈交代作用;③矿区—富稀土碳酸岩墙的δ~(13)C值为-7.2‰～-4.7‰,δ~(18)O价值为11.9‰～16.4‰,表明其碳酸岩岩浆并非原始地幔来源,而可能与俯冲板块携带的沉积碳酸盐岩与地幔流体在深部的高温混合熔融有关。碳酸岩墙中白云石与方解石之间的碳和氧同位素分馏均小于0‰,说明该碳酸岩墙中的白云石与方解石并非同成因矿物,至少其中之一为 相似文献
6.
鄂尔多斯盆地奥陶系马家沟组马五段白云岩的同位素地球化学特征 总被引：4，自引：0，他引：4
鄂尔多斯盆地中央气田奥陶系马家沟组马五段白云岩是重要的油气储集层,多年来,马家沟组白云岩的成因问题一直是地质研究者讨论的热点话题.对马五段白云岩的C、O、Sr同位素地球化学资料的分析表明,孔洞充填的白云石(含鞍状白云石)和白云岩的δ13C、δ18O值极其近似,且白云岩的δ18OPDB值比奥陶纪海水值要偏负1.752‰～4.395‰(平均2.911‰);成岩流体(水)的占δ18OSMOW平均值为+8‰,比当时海水值偏正;87Sr/86Sr比值比奥陶纪海水87Sr/86Sr比值要高.从C、O同位素数据上看,形成白云岩和沉淀于孔洞中的白云石(含鞍状白云石)的流体为同源流体;造成白云岩的δ18O值偏负的原因主要是埋藏条件的"温度效应";87Sr/86Sr比值偏高可能是交代流体来自或流经了富含放射成因Sr的铝硅酸盐基底或硅质碎屑岩.这些特征表明马五段白云岩很可能形成于埋藏环境. 相似文献
7.
陈家坝铜铅锌多金属矿床为近年来在陕西勉(县)-略(阳)-宁(强)铜金镍矿化集中区新发现的铜铅锌多金属矿床。为了查明陈家坝矿床成矿物质来源,笔者开展了系统的C、H、O、S和Sr同位素地球化学研究。结果表明,陈家坝矿区的围岩的δ~(13)CPDB值范围-0.93‰～1.44‰,平均值为0.35‰,δ~(18)OV-SMOW值范围14.14‰～27.49‰,平均22.1‰,为沉积成因海相碳酸盐岩。脉石矿物白云石的δ~(13)CPDB范围在-0.53‰～-0.89‰,δ~(18)OV-SMOW值范围12.12‰～13.23‰,指示成矿流体中的CO_2主要来自岩浆水,少量CO_2来源于围岩海相碳酸盐岩的溶解作用。成矿流体中δD值范围-91‰～-72‰,δ~(18)OH矿流体以岩浆流体为主。成矿流体与围2岩的水-岩反应是导致该区铜铅锌2矿床中白云石和黄铜矿、闪锌矿和方铅矿矿物沉淀结晶的主要机制。矿石金属硫化物δ34S值范围4.88‰～8.90‰,平均值为7.37‰,介于岩浆硫与海水硫之间,且与矿集区内典型的徐家沟铜矿床矿石矿物δ34S变化区间重叠,表明硫主要来自于岩浆硫,部分硫来自海水硫酸盐。矿石中黄铁矿的初始锶同位素比值87Sr/86Sr比值为0.72,高于赋矿围岩锶同位素比值,接近大陆地壳的87Sr/86Sr比值(0.719),指示了成矿流体流经了雪花太坪组地层,并与其中具有高87Sr/86Sr比值的白云岩进行水岩反应及同位素交换。 相似文献
8.
激光显微取样技术在川东北飞仙关组鲕粒白云岩碳氧同位素特征研究中的应用 总被引：10，自引：0，他引：10
显微取样碳氧同位素分析技术利用高聚焦激光束与碳酸盐岩样品作用,是一种在显微薄片下对岩石特定组构产生CO2的有效方法,其空间分辨率20～50μm,δ13C和δ18O的最好分析精度可达±0.22‰(σ),可以为碳酸盐岩碳氧同位素提供“高分辨率、原位”数据,微区分析是同位素测试发展的重要方向。用该技术对川东北飞仙关组鲕粒白云岩地球化学特征进行的研究表明,它可避免样品不纯带来的解释上的误差,为解释鲕粒白云岩成因提供了较为准确的地球化学信息,可进一步认识川东北飞仙关组鲕粒白云岩的成因问题。各种产状白云石的δ13C‰(PDB)值均大于当时海水值,说明白云石化流体没有淡水注入;而δ18O‰(PDB)分布较为离散,伴随白云石晶体大小增加,δ18O‰(PDB)值明显偏负,说明白云石化作用过程经历了埋藏加深、温度升高的过程,并且白云石化流体远离卤水源,其咸化程度减弱,为鲕粒白云岩的卤水渗透回流成因提供了有力的证据。 相似文献
9.
《大地构造与成矿学》2015,(6)
陕西南郑马元层控型铅锌矿床位于扬子板块北部碑坝穹隆构造的南缘,呈似层状产于震旦系灯影组角砾状白云岩构造带中。矿石矿物为闪锌矿、方铅矿,脉石矿物有白云石、石英、重晶石、方解石和固体沥青。矿区明显发育早期微晶脉状和晚期(成矿期)粗晶团斑状热液白云石。本文对马元铅锌矿床两类热液白云石及围岩的C、O、Sr同位素及稀土元素(REE)地球化学特征进行了对比研究。结果表明:早期脉状白云石的δ~(13)C(0.18‰)、δ~(18)O(-7.39‰)及~(87)Sr/~(86)Sr(0.70967)值与围岩震旦系白云岩大致一致,表明成矿流体中C、O、Sr来源于震旦系白云岩的溶解,稀土元素具明显的Eu正异常(δEu=1.78),可能反映了其形成于较强的还原环境。成矿期团斑状白云石δ~(13)C值(-2.51‰~0.93‰)与围岩震旦系白云岩(-3.2‰~1.33‰)一致,δ~(18)O值(-12.91‰~-10.95‰)较围岩(-9.2‰~-3.85‰)平均偏低5.7‰,且团斑状白云石具有较围岩白云岩高的稀土总量和~(87)Sr/~(86)Sr值,表明流体可能流经了具有高87Sr/86Sr值和高稀土总量的基底或上覆碎屑岩系,其较围岩偏低δ~(18)O值和Eu正异常(δEu=1.42)可能与流体具有较高的温度有关。早期脉状白云石可能与震旦系地层中封存的低温压实作用流体有关,晚期(成矿期)与团斑状白云石有关的成矿期流体可能主要与循环达基底的深部中低温流体有关。 相似文献
10.
辽西凌源雾迷山组碳酸盐岩碳氧同位素和Mn/Sr比值数据反映了碳酸盐岩的原始沉积特征.δ13CPDB数值范围-2‰～2‰,δ18OPDB数值范围为-10‰～-4‰,其平均值分别为0.15‰,-6.2‰,碳同位素组成具有旋回性变化特征.在雾迷山组一段中上部,δ13C表现出明显的正漂移,可能为藻类的大量繁殖、有机碳增加所引起.δ18O的增加为气候变冷和冰川作用的结果.在δ13C为负值的层段,δ18O数值较高.碳氧同位素组成的这种特征可能与海平面变化有关. 相似文献
11.
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
12.
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