青海-甘肃民和盆地油页岩成因类型及特征

利用岩心、钻井和分析测试资料,对民和盆地油页岩的沉积环境、层序地层、赋存、工业品质和地球化学特征进行了研究,将民和盆地油页岩划分为3种成因类型：油一层为深湖—半深湖低含油率腐泥型油页岩,油三层为浅湖相低含油率腐殖—腐泥型油页岩,油四层为湖沼相中含油率腐泥—腐殖型油页岩。研究成果表明：形成于深湖—半深湖相的油一层分布范围广,厚度较大,油页岩含油率不高,属高灰分低含油率的油页岩;形成于湖沼相的油四层厚度较小,平面上分布不稳定,含油率较高,属中灰分中含油率的油页岩。     

Geochemical and palynological indicators of the paleoecology of the River Gem coal bed, Whitley County, Kentucky

The River Gem coal bed (upper Westphalian A) was sampled at five sites in a single mine in Whitley County, Kentucky. Previous petrographic and sulfur analyses of the collected interval samples showed that the coal bed could be divided into a basal low-sulfur lithotype, a middle high-sulfur bone lithotype and an upper high-sulfur lithotype. At one location a high-sulfur rider unit is present. In this study we have conducted detailed palynological analyses on all of the interval samples and ash geochemistry on the upper high-sulfur lithotype intervals and two of the basal high-sulfur basal lithotype intervals.Geochemical analyses show that As and Pb are generally high in the high-sulfur upper lithotypes from all five sites. Carbonates, having associated high levels of Ba and Sr, are important in the ash geochemistry of the lower, low-sulfur lithotypes. Ga, Ge and W are enriched in the higher vitrinite lithotypes among the low-sulfur samples. The basal lithotype at each of two sites, which was analyzed in detail, is enriched in yttrium plus the lighter rare earth elements.The basal low-sulfur lithotypes are dominated by arboreous lycopod spores. The middle, low-sulfur portion of the bed is dominated by herbaceous lycopsids (Densosporites) at the base of the unit and becomes increasingly enriched in Lycospora towards the top of the unit indicating that the peat-forming environment became wetter. The greatest arboreous lycopod spore abundances in the upper, high-sulfur portion the bed, along with an overlying marine roof, indicates that peat deposition was terminated by a marine inundation.     

Geochemistry of the blue gem coal bed, Knox county, Kentucky

The Blue Gem coal bed (Middle Pennsylvanian Westphalian B, Breathitt Formation), has low-ash (with some sample sites having less than 1% ash) and low-sulfur contents through parts of Knox County, Kentucky. Most collection sites exhibit similar vertical elemental trends in ash geochemistry. The relatively high-ash (>1% ash) lower part of the bed displays enrichment in TiO₂, Zr, Cr, V and Ni; Co, Zn, Rb and Mn show enrichment at some sites. A low-ash (<1% ash) middle part of the bed displays enrichment in Sr, Ba and CaO; Fe₂O₃ is enriched in samples with carbonate minerals. The upper part of the bed contains >1% ash and a relative enrichment in SiO₂, K₂O and Rb and a relative decrease in Cu, Ni, Co, Ba and Mn when compared to the middle part of the bed. Principal components analysis indicates that the samples with an ash content 0.63–1.0% show associations for Ni, Cu, Cr and Co. Samples with between 1.01–2.0% ash display strong element associations that suggest increased clastic sediment contributions (TiO₂, Zr, K₂O, Rb, SiO₂). The low-ash content and the upwards decrease in trace concentrations both suggest that the Blue Gem peat swamp was ombrotrophic through at least a part of its geologic history.     

The geochemistry of tungsten in Bulgarian coals

This paper discusses the tungsten geochemistry in coal, based on the behavior of this element in 14 Bulgarian deposits. The W contents range from 0.5–4335 ppm in the ash and from 0.01–784 ppm in the coals. In four of the deposits the tungsten content proved to be 16 to 100 times higher than the Clarke value for sedimentary rocks. No correlation has been found between the W concentration and either the age of the coal-bearing strata or the coal rank. The deposits were divided in three groups on the basis of the relationship between tungsten and ash content. The role of sorption ash and terrigenous ash in tungsten binding was evaluated for each group. The correlation between tungsten and organic matter is demonstrated by the increased contents of tungsten in the ash of the low-ash coals, its concentration in the lighter coal fractions, its extraction from the coals by HF and NaOH only, and by model experiments. Sorption ash concentrates tungsten; terrigenous ash is a carrier of tungsten.Of the petrographic constituents of coal, vitrain was found to concentrate the largest amounts of tungsten.In two of the deposits richest in tungsten, there is a very distinct zonality in its vertical distribution — tungsten concentration decreases from the bottom to the top of the coal bed. This zonality might be explained by the diffusion (syngenetic or diagenetic with respect to the coal-forming process) through the coal bed of aqueous solutions enriched in tungsten.The wide range of variation of the tungsten concentrations, the considerable differences in the mean contents and the dispersions between the individual deposits show that tungsten is very sensitive to the differences of the source area.Coal deposits enriched in tungsten may be expected in the following favourable environments: (1) in areas with nitrogen-bearing thermal waters containing increased amounts of tungsten; (2) source areas with tungsten mineralizations; and (3) country rocks consisting of acid granitoids whose Clarke values of tungsten are the highest as compared to the other types of rocks.     

Coal fly ash interaction with environmental fluids: Geochemical and strontium isotope results from combined column and batch leaching experiments

The major element and Sr isotope systematics and geochemistry of coal fly ash and its interactions with environmental waters were investigated using laboratory flow-through column leaching experiments (sodium carbonate, acetic acid, nitric acid) and sequential batch leaching experiments (water, acetic acid, hydrochloric acid). Column leaching of Class F fly ash samples shows rapid release of most major elements early in the leaching procedure, suggesting an association of these elements with soluble and surface bound phases. Delayed release of certain elements (e.g., Al, Fe, Si) signals gradual dissolution of more resistant silicate or glass phases as leaching continues. Strontium isotope results from both column and batch leaching experiments show a marked increase in ⁸⁷Sr/⁸⁶Sr ratio with continued leaching, yielding a total range of values from 0.7107 to 0.7138. For comparison, the isotopic composition of fluid output from a fly ash impoundment in West Virginia falls in a narrow range around 0.7124. The experimental data suggest the presence of a more resistant, highly radiogenic silicate phase that survives the combustion process and is leached after the more soluble minerals are removed. Strontium isotopic homogenization of minerals in coal does not always occur during the combustion process, despite the high temperatures encountered in the boiler. Early-released Sr tends to be isotopically uniform; thus the Sr isotopic composition of fly ash could be distinguishable from other sources and is a useful tool for quantifying the possible contribution of fly ash leaching to the total dissolved load in natural surface and ground waters.     

The Hekla 1947 tephra in the north of Ireland: regional distribution,concentration and geochemistry

A cryptotephra layer from the eruption of Hekla in 1947 has recently been discovered in Irish peatlands. This tephra layer represents the most recent deposition of volcanic ash in the UK prior to the eruption of Eyjafjallajökull in 2010. Here we examine the concentration and geochemistry of the Hekla 1947 tephra in 14 peat profiles from across Northern Ireland. Electron probe microanalysis of individual tephra shards (n = 91) reveals that the tephra is of dacitic–andesitic geochemistry and is highly similar to the Hekla 1510 tephra, although spheroidal carbonaceous particle profiles can be used for successful discrimination of the two layers. The highest concentrations of Hekla 1947 are found in western sites, probably reflecting the pathway of the ash fall event due to the prevailing wind direction. Comparable tephra concentrations from two cores (1 km apart) from a single bog and from nearby sites may suggest that tephra shard concentrations in peat profiles reflect ash fallout densities across a specific region, rather than site‐specific factors associated with peatlands. This paper firmly establishes Hekla 1947 as a useful chronostratigraphic marker for the twentieth century, although within a restricted zone. Copyright © 2012 John Wiley & Sons, Ltd.     

The age of glacier peak tephra in west-central Montana

At Sheep Mountain Bog, near Missoula, Montana, a late-glacial tephra, that probably fell in late summer, is preserved as an 8-mm-thick graded bed overlain by another 8 mm of redeposited ash mixed with lake deposits. Sediment surrounding the ash was ¹⁴C dated to about 11,200 yr B.P. Electron-microprobe analyses of the volcanic glass and hornblende phenocrysts from this ash layer indicate that they are similar in major-element chemistry to those of Glacier Peak layer G previously considered to be about 12,000 yr old or older.     

火山灰年代学:原理与应用

火山灰(2mm)等时标志层是火山灰年代学研究的基础。火山灰地层的直接或间接测年依赖于火山灰中存在合适的原生矿物(如:透长石、锆石、磷灰石)或外来物质(如:炭化木)。然而大多数火山灰沉积层,尤其是远源火山灰,其主要由岩浆源碎屑构成,开展测年显得十分困难。利用火山玻璃(岩浆)的地球化学,是一种被广泛应用的替代性方法。火山玻璃作为岩浆源物质普遍出现在各类近源、远源可见火山灰层和显微火山灰中,其主量、微量元素含量和特定的同位素组成能被电子、激光和离子探针技术准确测定。近源-远源玻璃化学成分的相互匹配,使得火山灰等时标志层得以在时间和空间上相互关联,构成有力的地层学工具,用以同步各类环境、考古和火山活动记录。近源火山沉积和远源火山灰层中的年龄信息得以实现交叉验证和整合。远源海洋、湖泊沉积中的相对年龄信息(氧同位素地层学,年纹层年代学)也为揭示火山活动、古环境变化和考古学事件的时间顺序提供了可能。火山灰年代学在地球科学中应用广泛,尤其是对于第四纪研究,其在同步各类记录从而评估火山活动、气候/环境变化和人类演化/迁移的因果关系中具有至关重要的作用。     

A little goes a long way: discovery of a new mid-Holocene tephra in Sweden

This pilper reports the presence of a volcanic ash layer in western Sweden which is geochemically identiticd as the Kebister tephra. This tephrdpresenceof (dated c . 3600 ¹⁴C BP) was discovered at Kebister, Shetland and thc rcsults presented here indicate that the deposit may have a greater geographical distribution than previously thought. The geochemistry of the volcanic glass was analysed by using discrete grain electron probe microanalysis (EPMA). Thc SiO₂ content of the glass ranges from 66.19 to 71.96%, FeO content 2.73 to 6.07% and MgO content 0.15 to 0.57%_˜ The tephra can he distinguished from the more widespread Hekla 4 tephra ( c . 3800 ¹⁴C BP) on the basis of calcium and magnesium contents.     

Rare earth elements in a sampled coal from the Pirin deposit,Bulgaria

Rare earth elements (La, Ce, Sm, Eu, Tb, Yb, and Lu) in a columnar section of the coal of the Pirin deposit, Bulgaria, have been determined by neutron activation analyses.The REE content in the coals is lower than the average REE content of shales from North America, Europe, and the Soviet Union. The REE abundances increase with the increasing ash content of the coals. The bottom of the seam is slightly enriched in REE, the trend being more pronounced in HREE (Tb, Yb, Lu). The REE content depends on the thickness of the coal layers: the thin coal layers are enriched in REE as compared to the thick ones.The chondrite-normalized distribution patterns are very uniform. They are characterized by a negative Eu anomaly whose mean value is 0.30 (varying in the individual samples from 0.21 to 0.49) and a positive Lu anomaly. It is supposed that the Eu anomaly is inherited from the source rocks.The shale-normalized distribution patterns show a distinct relative enrichment in HREE and a negative Eu anomaly. The relative enrichment in HREE is a specific feature of the REE geochemistry in the Pirin deposit. The LREE/HREE ratio is lower than that of composite shale; it increases with the increasing ash content of the coals and from the bottom to the top of the coal bed.REE are bound predominantly to the aluminosilicates of the mineral matter in the coals. All REE are positively correlated to the ash, Si, Al, Fe, and Na.The source of REE in coals is mainly the suspended terrigenous material. The specific enrichment of REE in the ash of low-ash coals is a result of the interaction between the dissolved REE and the products of disintegration and decay of organic substances, mainly the humic acids.     

新疆塔西南区海相白垩系—第三系界线的地球化学异常

新疆塔里木盆地西南地区海相白垩系—第三系的界线粘土层发现于依格孜牙组和吐依洛克组之间。这一层具有相当复杂的元素组合 ,存在诸多元素异常。它不仅是一条生物界线 ,而且是一条地球化学界线。这一异常事件层代表了白垩纪与第三纪之交的突变事件 ,具有全球的一致性和等时性 ,因而具有自然界线性质。     

The chemical composition including the Rare Earth Elements of the three major glass types of Europe and the Orient used in late antiquity and the Middle Ages

Sets of 20 soda ash glasses, 16 soda lime glasses and 23 wood ash glasses mainly from excavations in Europe (additional soda ash glasses from Egypt) were analysed on 61 chemical elements. Average SiO₂ is about 62% in soda glasses and 50% in wood ash glasses. The three groups of glasses contain on average 13% Na₂O, 18% Na₂O and 13% K₂O as fluxes to lower the melting temperature of quartz at their production. The starting materials beside quartz were halophytic plant ash for soda ash glass, trona (Na₃H(CO₃)₂·2H₂O) and lime (clamshells) for soda lime glass and beech ash for wood ash glass. Each of the three major glass types contains specific Rare Earth Element (REE) concentrations mainly contained in quartz and its intergrown minerals. 50 Paleozoic and Mesozoic sandstones from Central Europe represent the quartz composition. The REE pattern of these glasses apparently indicates major compositional stages of the Continental Earth's Crust. The boron to lithium and sodium to potassium ratios as in seawater suggest reactions of materials for soda glass with seawater. Negative Ce anomalies in the three glasses are caused by reactions of quartz with seawater.     

淮南二叠纪煤及其燃烧产物地球化学特征

采用仪器中子活化分析法INAA（instrumental neutron activation analysis)测试了淮南煤田二叠纪主采煤层原煤煤样的地球化学组成，用X－射线荧光光谱XRFS（X－ray fluorescence spectrometry)测试了田家庵和洛河电厂的粉煤灰地球化学组成并与煤样作了对比分析，用电子探针测试了飞灰中主要类型颗粒的化学组成，淮南煤中多数微量元素属正常水平，与克拉克值相比，元素Se,S,As,Sb,Br,U和Cl等在煤中趋于富集，其他元素均趋于分散，有机亲和性弱的亲石元素趋于在粉煤灰中聚集，与铁关系密切的金属元素在粉煤灰中有明显的富集，有机亲合性强的元素在燃烧过程中趋于以气态形式向空气中逸散，粉煤灰中因矿物与粒度的分异明显，致使其化学组成在不同的粒度级和比重级中的分布也有较大的不同，飞灰中一些不定形颗粒主要由铁的氧化物和少量其他金属氧化物组成，硅酸盐类颗粒主要由硅，铝和铁的氧化物所组成，而玻璃珠主要由硅和铝的氧化物组成，残碳中测得的砷，硫和氯的含量最高，说明其对这些元素具有较强的吸附能力，研究粉煤灰的成分特点有助于粉煤灰的综合利用和评价其对环境的 影响。     

Correlation of the Rockland ash bed,a 400,000-year-old stratigraphic marker in northern California and western Nevada,and implications for middle Pleistocene paleogeography of central California

Outcrops of an ash bed at several localities in northern California and western Nevada belong to a single air-fall ash layer, the informally named Rockland ash bed, dated at about 400,000 yr B.P. The informal Rockland pumice tuff breccia, a thick, coarse, compound tephra deposit southwest of Lassen Peak in northeastern California, is the near-source equivalent of the Rockland ash bed. Relations between initial thickness of the Rockland ash bed and distances to eruptive source suggest that the eruption was at least as great as that of the Mazama ash from Crater Lake, Oregon. Identification of the Rockland tephra allows temporal correlation of associated middle Pleistocene strata of diverse facies in separate depositional basins. Specifically, marine, littoral, estuarine, and fluvial strata of the Hookton and type Merced formations correlate with fluvial strata of the Santa Clara Formation and unnamed alluvium of Willits Valley and the Hollister area, in northwestern and west-central California, and with lacustrine beds of Mohawk Valley, fluvial deposits of the Red Bluff Formation of the eastern Sacramento Valley, and fluvial and glaciofluvial deposits of Fales Hot Spring, Carson City, and Washoe Valley areas in northeastern California and western Nevada. Stratigraphic relations of the Rockland ash bed and older tephra layers in the Great Valley and near San Francisco suggest that the southern Great Valley emerged above sea level about 2 my ago, that its southerly outlet to the ocean was closed sometime after about 2 my ago, and that drainage from the Great Valley to the ocean was established near the present, northerly outlet in the vicinity of San Francisco Bay about 0.6 my ago.     

层间氧化带砂岩型铀矿床微生物地球化学特征及与铀成矿的关系研究——以吐鲁番-哈密盆地十红滩铀矿床为例

通过样品采集、细菌培养和鉴定等,首次在中国大型的十红滩层间氧化带砂岩型铀矿床容矿层中发现不同种群的细菌。氧化带主要分布铁细菌、硫杆菌、硝化菌等好氧菌,矿石带主要分布厌氧的硫酸盐还原菌,其种类和数量上具明显的生物地球化学分带性,并与岩石的地球化学分带性一致。首次利用容矿层的硫酸盐还原菌在室内进行了硫酸盐还原试验。根据细菌的代谢特征,结合硫酸盐还原菌还原试验,分析了细菌在层间氧化带形成、铀氧化迁移和还原成矿过程中的作用。     

Tephrochronology of the western Gulf of Mexico for the last 185,000 years

Tephra in 31 piston cores from the western Gulf of Mexico and 7 piston cores from the equatorial Pacific were analyzed by electron microprobe. Six ash layers in the western Gulf of Mexico were easily distinguished by TiO₂, FeO, and CaO contents and correlated by geochemistry in order to determine the distribution pattern for each ash layer. Correlation by geochemistry is an easier, more accurate method than biostratigraphic correlation; some of the tephras were miscorrelated by biostratigraphy. The six tephras were dated by geochemical identification in a piston core with oxygen-isotope stratigraphy and the ages are Y5 (30,000 yr B.P.), Y6 (65,000 yr B.P.), Y8 (84,000 yr B.P.), X2 (110,000 yr B.P.), W1 (136,000 yr B.P.), and W2 (185,000 yr B.P.). Data from this study corroborated correlations of the Y8 tephra in the western Gulf of Mexico with the D layer in the eastern equatorial Pacific Ocean. None of the other five layers in the Gulf of Mexico, however, were found in the Pacific Ocean. The limited distribution of the Y5, Y6, X2, and W2 ash layers close to Mexico indicates possible sources in Mexico. Tephra from the late Pleistocene La Primavera pumice in Mexico, however, does not correlate with the marine tephra.     

Testing the reliability of the JEOL FEGSEM 6500F electron microprobe for quantitative major element analysis of glass shards from rhyolitic tephra

Coulter, S. E., Pilcher, J. R., Hall, V. A., Plunkett, G. & Davies, S. M. 2009: Testing the reliability of the JEOL FEGSEM 6500F electron microprobe for quantitative major element analysis of glass shards from rhyolitic tephra. Boreas , 10.1111/j.1502-3885.2009.00113.x. ISSN 0300-9483.
Electronprobe microanalysis is now widely adopted in tephra studies as a technique for determining the major element geochemistry of individual glass shards. Accurate geochemical characterization is crucial for enabling robust tephra-based correlations; such information may also be used to link the tephra to a specific source and often to a particular eruption. In this article, we present major element analyses for rhyolitic natural glass standards analysed on three different microprobes and the new JEOL FEGSEM 6500F microprobe at Queen's University Belfast. Despite the scatter in some elements, good comparability is demonstrated among data yielded from this new system, the previous Belfast JEOL-733 Superprobe, the JEOL-8200 Superprobe (Copenhagen) and the existing long-established microprobe facility in Edinburgh. Importantly, our results show that major elements analysed using different microprobes and variable operating conditions allow two high-silica glasses to be discriminated accurately.     

钻井现场有机地球化学录井与油气识别评价技术

在现场钻进过程中，尤其是在油基泥浆及各种添加剂烃类污染、地质录井难以确定真假油气显示的情况下，有机地球化学录井对确定油气显示有独特的作用。但由于其烃类污染对岩屑罐顶气、岩石冷溶烃、岩石热解等常规地球化学录井技术有不同程度的影响，其检测数据通过校正污染后才能用于含油气性评价。为此，在现场开展了钻井泥浆及各种添加剂中烃类有机地化检测试验，对泥浆中轻烃（C1－C12）、萃取烃（C1－C35）和岩石冷溶烃进行动态检测，研究其烃类组成及变化特征，对钻进中真假油气显示、油气层质量及产能大小、油气烃类母质类型、储油层确定等及时作出解释与评价，为油气勘探与开发快速提供地球化学依据。     

Age and significance of the Platypus Tuff Bed,a regional reference horizon in the Upper Permian Moranbah Coal Measures,north Bowen Basin

The Platypus Tuff Bed in the Permian Moranbah Coal Measures provides a basin‐wide marker horizon traceable for over 300 km along strike. The bed is a tephra event unit, the product of a large‐scale volcanic eruptive episode involving a pyroclastic volume > 10 km³. The relatively even thickness (～1–1.5 m) of the tuff across the entire northern Bowen Basin (～10 000 km²) implies a distant source. The tuff is ash‐rich and its original geochemistry has been compromised by diagenetic alteration. Crystal content (10–15%) is dominated by quartz, suggesting a rhyolitic association. SHRIMP U–Pb analysis of zircons indicates an age of 258.9 ± 2.7 Ma for the Platypus Tuff Bed, confirming the Late Permian age that has generally been assigned to the Blackwater Group. The age framework now apparent for the coal‐bearing Blackwater Group suggests an average depositional rate ranging from ～133 m/10⁶ years for its eastern depocentre in the northern Bowen Basin to ～70 m/10⁶ years in more marginal settings to the west.