Investigation of failures in Irish raised bogs

This paper presents the results of field geophysical testing and laboratory testing of peat from Carn Park and Roosky raised bogs in the Irish Midlands. The motivation for the work was highlight the importance of these areas and to begin to attempt to understand the reasons for the failure of the bogs despite them having surface slopes of some 1°. It was found that the peat is typical of that of Irish raised bogs being up to 8 m thick towards the “high” dome of the bogs. The peat is characterised by low density, high water content, high organic content, low undrained shear strength and high compressibility. The peat is also relatively permeable at in situ stress. Geophysical electrical resistivity tomography and ground penetrating radar data shows a clear thinning of the peat in the area of the failures corresponding to a reduction in volume from dewatering by edge drains/peat harvesting. This finding is supported by detailed water content measurements. It was also shown that the peat base topography is relatively flat and indicates that the observed surface movement has come from within the peat rather than from the material below the peat. Potential causes of the failures include conventional slope instability, the effect of seepage forces or the release of built-up gas in the peat mass. Further measurements are required in order to study these in more detail.     

Hydrology and drainage of peatland

Peat is an accumulation of partially decomposed plants, chiefly mosses, herbs, and trees, to form a deposit called bog. Complete decomposition is primarily inhibited by a deficiency of oxygen induced by waterlogging. In the upper layers of raised bogs and in the so-called blanket bogs, acidity and very low levels of phosphorus may also contribute to impairing decomposition. Peat types have been classified into blanket, raised, and fen peat. Further subdivisions have been made on the basis of the plant composition and degree of decomposition. Blanket peat is so called because it covers the landscape, hill and valley. On the other hand, raised peats are confined to low-lying ground and valleys, and higher ground often protrudes through as islands of mineral soil ground. The blanket/raised/fen classification has relevance to hydrology and drainage, in particular to the mode of formation and to the type of drainage solution including outfalls. The nature of the plant composition and degree of humification have relevance chiefly to physical properties but especially permeability, bulk density, and moisture content, which also relate to hydrology and drainage. This article examines the formation of peat in a hydrological context and the drainage of peat deposits through the application of drainage theory to the peat and subpeat deposits, including glacial drift and bedrocks.     

Some peculiarities of holocene processes in Western SiberiaZur holozängeschichte der westsibirischen torfmooreQuelques singuliarités des processus holocènes sur le territoire de la Sibérie occidentale

The authors deal with problems of the origin of peat in the territory of the West Siberian Lowland where Holocene processes are sufficiently widespread to be representative of this world-wide phenomenon. Here, for example, are found the most extensive peat bogs of the Earth. The authors deal with the stratigraphy of these peat bogs and the reconstruction of Holocene conditions in the West Siberian Lowland. The development of peat bogs has considerably modified landscape features since the retreat of the last glaciation, i.e., during the last 10,000 to 11,000 years. The peat bogs began to develop simultaneously in thousands of depressions after the ice cover had melted. Later they merged into vast peaty bog regions. Without any intervention by man the peat bogs will cover all of Western Siberia in the course of several thousands of years. The development of extensive peat bogs is due to an irregular advance of floods on Siberian rivers which leads to a rise in the water level on tributaries of great rivers and to a retardation of the discharge of flood waves In the conclusion the authors point to the problems of economic use of swampy regions and to questions of land reclamation that must be answered before economic use of the territory (mainly in connection with extensive oil and gas deposits in these regions) can be fully effective.     

新疆准东煤田西黑山勘查区西山窑组煤相特征

以新疆准东煤田西黑山勘查区西山窑组煤层为研究对象,采用成因参数法和煤相图解方法,同时结合沉积学方法进行煤岩、煤相分析,探讨泥炭沼泽类型及其演化规律。煤相参数研究显示,B1、B11、B21和B2煤层煤相总体为偏干燥的湿地森林和湿地森林沼泽,B12、B3和B4-5煤层总体为干燥森林沼泽;垂向上B1、B2、B3、B31和B6煤表现出显著的由湿地森林沼泽或偏干燥的湿地森林沼泽向干燥森林沼泽演化,反映覆水程度逐渐变浅,泥炭沼泽表面逐渐趋于干燥,表明成煤期泥炭堆积速率与基底的相对沉降速率持平或略高于基底沉降速率。     

Peat/coal type and depositional environment—are they related?

Four bogs in New Zealand were investigated in order to understand the relationship between peat type and depositional environment. This relationship is important because peat type translates into coal type, and coal types can ultimately be used to infer how and under what conditions the original peat bog formed. In our study, no correlation was found between peat type and depositional environment in the four bogs examined. Moreover, no correlation was found between peat type and either tectonic setting or climate. Water table level and degree of fluctuation are the only parameters which seem to have a good causative relationship on peat type.The bogs, Whangamarino, Moanatuatua and Kopouatai in the North Island and Sponge Swamp in the South Island, all have different depositional settings ranging from coastal plain, to fluvial-meandering and fluvial-braided river floodplain. We found no diagnostic peat types that would allow those different environments to be distinguished from studies of the peat. Data from other tropical and temperate climate peat bogs also support our contention that no diagnostic peat types can distinguish particular depositional settings. However, the level and variability of water table does have a correlation, one that is also seen in bogs elsewhere.From our observations, we infer that the validity of using maceral ratios (directly related to coal type) to indicate depositional environment should be questioned. At best, coal type only represents to what degree the original plant components were degraded, but not how they were degraded. To infer other parameters such as depositional environment, tectonic setting or climate, other data (e.g. distribution of surrounding sediment types, palynology, etc.) must be collected and assessed.     

泥炭沼泽的演化及其机制

泥炭沼泽的演化普遍存在,演化的实质是在成因因素有利的配合下,沼泽植物群落发生了变化乃至更替。根据泥炭植物残体分析和煤层的煤岩、煤化学研究,可以了解泥炭沼泽的演化和形成煤层的原始泥炭沼泽的演化。      

Applications of Remote-Sensing Techniques in Peat Resource Investigations in Zoig■

The paper presents an example of the application of remote-sensing techniques in peat resource investiga-tions. The study was carried out in the Zoige region. The optimal imagery time (during October) and theoptimal band (MSS_7) of Landsat data were selected. The preferred images were processed optically and bycomputer and interpreted in a comprehensive way. And in-situ spectrum measurements and drilling verificationwere carried out.The identification signature of the peat bogs in Zoige was defined. The feature of the identifi-cation signature for peat was that the peat bog area showed a dark tone with lower reflectance in images of thefour MSS bands. The distribution range of peat bogs in the region was exactly located. The types of peat bogswere distinguished. The total peat area of 4038 km~(2) was defined with a total reserve of 5 billion m~3. The resultof the study indicates that the large-area, small-scale investigation of peat resources by use of satelliteremote-sensing data is an advanced method. by which the work efficiency can increase by about 20 times.     

Occurrence and morphology of pyrite in Bulgarian coals

Coals with different degrees of coalification (ranging from lignite to anthracite) from seven Bulgarian coal basins have been investigated. The forms of pyrite and their distribution have been established. The types found are: massive pyrite, represented by the homogeneous, cluster-like and microconcretionary varieties; framboidal pyrite, appearing in inorganic and bacterial forms; euhedral pyrite, which is either isolated or clustered; anhedral pyrite, in its infilling and replacement varieties; and infiltrational pyrite, as a replacement or infilling mineral.Most of the forms of the euhedral, framboidal and massive pyrite developed during peat deposition. The anhedral replacement pyrite formed in the peat bed during early diagenesis. Infiltrational pyrite filled fractures and cleats formed during the diagenesis, catagenesis and metagenesis.Both similarities and differences with respect to the distribution of the pyrite types have been determined between coals of different ranks from Bulgarian coal basins. These differences are due to: the presence of Fe and S in the rocks adjacent to ancient peat bogs; the activities of ground and surface waters which brought Fe and S into the peat bogs; the geochemical character (pH and Eh) of the peat bogs and the sulphur bacteria development; and the tectonic situation during diagenesis, catagenesis and metagenesis.     

Formation of Lower and Middle Jurassic Coaliferous Sequences in the Northern Caucasus

Pliensbachian coaliferous sequences were formed along the southern margin of the Stavropol Uplift in various paleogeographic environments. Therefore, peat bogs are developed in various landscape zones. In the southern Kuban coaliferous district, which adjoins the tectonically active central Caucasus, coaliferous sediments were formed in river valleys, whereas peat bogs were developed in swamped valleys. In the northern Kuban and Baksan coaliferous districts situated away from this region, coaliferous sediments were formed under conditions of alluvial–deltaic and alluvial–lacustrine plains. Peat bogs were localized in the swamped alluvial–deltaic and alluvial–lacustrine plains. In the Laba–Urup and southeastern Baksan coaliferous districts situated far away from the tectonically active central Caucasus and dominated by partly isolated bays and lagoons (or coastal plains), peat bogs were formed in the swamped (partly isolated) bays and lagoons (or coastal plains). Similar environments of sedimentation and peat deposition were typical of the Daghestan coaliferous district in the early Aalenian and Bathonian of Middle Jurassic.     

Testate amoebae as a proxy for reconstructing Holocene water table dynamics in southern Patagonian peat bogs

Testate amoebae are abundant and diverse in Sphagnum peat bogs and have been used extensively as indicators of past water table depths. Although these unicellular protists are widely dispersed with globally similar hydrological preferences, regional variations in communities demand region‐specific transfer functions. Here we present the first transfer function for southern Patagonian bogs, based on 154 surface samples obtained from transects in five bogs sampled in 2012 and 2013. Significant variance was explained by pH, electrical conductivity and, in particular, water table depth. Transfer functions for water table were constructed using weighted averaging and evaluated by cross‐validation and independent test sets. The optimal transfer function has predictive ability, but relatively high prediction errors given the wide range in sampled water tables. The use of independent test sets, as well as cross‐validation, allows a more rigorous assessment of model performance than most previous studies. For a subset of locations we compare surface and subsurface samples to demonstrate significant differences in community composition, possibly due to vertical zonation. Our results provide the first quantification of hydrological optima and tolerances for several rare species, which may include Southern Hemisphere endemics and pave the way for palaeohydrological reconstructions in southern Patagonian bogs.     

早期煤化作用机制与有机质早期成烃演化

近年来，未熟和低熟油气田的发现、生物气藏的勘探和开发，极大地促进了对有机质早期转变的研究；而有机质早期转变机制的正确认识对于煤和干酪根中显微组分的成因、后期热演化都有着重要的影响。对早期煤化作用机制和有机质早期成烃作用的研究现状、进展及存在的问题进行了综述。     

The occurrence of Laacher See Tephra in Pomerania, NW Poland

A millimetre-thick bed of highly vesiculated pumiceous clasts was found in two peat bogs in Pomerania (NW Poland). Their phonolitic composition confirms the correlation with the Laacher See Tephra (LST). Based on the various CaO-Na₂O-K₂O content, most of these clasts can be linked with the Lower Laacher See Tephra (LLST), and some with the Middle Laacher See Tephra B (MLST-B). ¹⁴C dates obtained on peat samples are in agreement with an Allered stratigraphic position of that tephra. In several localities in NW Poland, it was found that there was no occurrence of tephra in peat bogs. Thus the presence of the LST is restricted to the northwestern fringes of Pomerania.     

华北地区晚石炭世岩相古地理特征及聚煤规律研究

通过分析华北地区晚石炭世的沉积环境及煤层分布特点,探讨了该区晚石炭世沉积相的典型类型,综合分析得出华北克拉通板块晚石炭世主要为陆表海环境,期间发生多次海侵海退事件,在郯庐断裂以东地区,主要发育有台地沉积体系、障壁一渴湖沉积体系及潮坪沉积体系;在盆地的北西缘地区发育潮坪泥炭沼泽,形成了海侵事件沉积,海退时期,中北部地区有利于发育潮坪泥炭沼泽和岛后泥炭沼泽,成为煤层的聚煤中心。     

中国泥炭资源

泥炭的形成和发展,直接受地表水热条件控制,后者又取决于形成时期的气候、地质。地貌及水文地质条件。文中据大量调查资料,叙述中国6个区的泥炭分布,扼要分析若干类型泥炭分布特征。在受河流活动控制并有泥炭形成的地区,泥炭沼泽分布呈现干流区少、支流区多,下游区少、上游区多的特点;在巨型构造湖盆区,泥炭沼泽可充分发展,形成泥炭层厚、空间展布广的巨型矿床;火山口湖盆型、堰塞湖盆型泥炭沼泽环境稳定,历经长期发育,可形成厚达9．0～9．5m的矿床;平原区湖盆型、河漫滩型泥炭,形成时受洪水事件影响,产出多层、较薄的泥炭。80年代本原地质矿产部通过对中国30个地质矿产局调查报告（未含台湾省）系统分析研究,获全国泥炭资源量46．87亿t（千重）。文中据国际泥炭学会（IPS）规定,按含水40％容重核算,1998年获资源量124．96亿t,证实中国泥炭资源分布的不平衡性,质量属中等,与泥炭资源丰富的国家相比,中国泥炭资源是较丰富的。     

Accumulation of heavy metals in Oostriku peat bog,Estonia: -site description,conceptual modelling and geochemical modelling of the source of the metals

Oxidation of sulphides leads to the dissolution of metals, which are transported with water and accumulate at geochemical barriers. Such barriers can form in peat bogs. This paper gives an introduction into the long-term processes in Oostriku peat bog where high accumulations of heavy metals are observed. Peat and water samples are analysed for Fe, As and heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) using different methods. A concept is based on the observations. Metals are leached by sulphide oxidation in the carbonate rocks upstream of the peat. The water feeds the peat from below. The metals are sorbed and precipitated in the peat. The sulphide oxidation is simulated to examine the origin and metal speciation in the water. The simulated solution is compared with the groundwater entering the peat. The results showed a fair agreement for the major constituents. There were considerable differences for species with low concentrations.     

白布勘探区龙潭组沉积环境及成煤条件分析

贵州大方县白布勘探区煤系地层龙潭组为海陆交互相沉积,厚度177～211m,含煤21～36层,煤层总厚18.04～30.29m,可采煤层6层。根据岩性、岩相特征自下而上分为3段,下段为潟湖—潮坪相沉积,并在大部分地区形成泥炭沼泽,形成了可采的33、28号煤层;中段为三角洲相,泥岩沼泽相多在三角洲分流河道间的湖沼区及湖波浪带基础上发育而成,煤层层位稳定,厚度不大;上段为潮坪三角洲相,该期构造活动趋于平稳,形成的煤层层位稳定,厚度大,6中煤0.39～6.88m,7号煤0～3.09m。三段厚度比较接近,反映该区晚二叠世期间地壳沉降均衡。沉积环境差异是本区成煤条件的主要控制因素。     

中国典型泥炭区现代植物的碳、氧同位素组成及在古环境研究中的意义

本文测定了中国 3个典型泥炭沼泽四川红原、吉林金川和哈尼的现代沼泽植物中的碳、氧同位素组成。吉林金川和哈尼的沼泽在相似的气候和环境条件下发育演化 ,而四川红原的泥炭发育在截然不同的气候条件下。结果表明 ,每个泥炭沼泽现代植物中的碳、氧同位素均有较大的离散度 ,表现为不同营养状况下的成沼植物之间的同位素差异 ;从δ1 3C值来看 ,三个沼泽中的植物均属C3植物 ;红原与金川、哈尼有着明显不同的现代植物稳定氧同位素组成 ,前者更富集1 8O。同一泥炭植物碳、氧同位素的不均一性要求在利用泥炭沉积物恢复过去气候变化方面一定要谨慎。非常有意义的是贫营养泥炭 (高位泥炭 )的成沼植物有着非常接近的同位素组成 ,揭示贫营养型泥炭可能是更为理想的过去全球变化信息档案     

Replicability and variability of the recent macrofossil and proxy-climate record from raised bogs: field stratigraphy and macrofossil data from Bolton Fell Moss and Walton Moss,Cumbria, England

Replication of results is a basic tenet of science, but in palaeoecology this is very time-consuming and the ‘signal’ is subject to ‘noise’. The derivation of proxy-climate signals from ombrotrophic peat was carried out originally using samples from open peat faces where the stratigraphic relationships could be easily observed. Now that such sections are rare and often degraded there is a need to demonstrate that data can be replicated from core profiles. Ten short cores taken from two adjacent bogs have been analysed for macrofossils and show a coherent series of changes, which are also similar to previous profiles from the same sites. It is concluded that variation between profiles is slight and less than observations of present vegetation mosaics might suggest. Recommendations for a standard approach to fieldwork on raised bogs that emphasises the utility of subfossil pool layers are proposed and the need for a secure chronology is stressed. © 1998 John Wiley & Sons, Ltd.     

The mechanized 'Gik' corer: seven years of use and improvement

Since 1980 the authors have been using a mechanized Gik corer for coring in marshlands and peat bogs. Final modifications to the equipment are described and shown in photographs and drawings.     

浅钻技术在若尔盖地区泥炭调查中的应用

泥炭是一种具有多种用途的宝贵自然资源,泥炭中的有机碳储量是研究全球碳库变化及碳循环过程的重要参数。由于泥炭多分布于沼泽中,且泥炭松软含水量大的特性,对于泥炭深度的调查、获取用于测试泥炭原状样品的质量不高,导致泥炭碳储量评价仍存在不确定性和偏差。笔者等在典型泥炭形成地若尔盖沼泽湿地地区,开展了浅钻泥炭调查取样工作,通过在泥炭斑块边缘及中心两种不同沼泽湿地地层开展的试验,验证了轻便钻机在难进入的沼泽湿地的适应性,配套的振动冲击工艺可高质量的获得无扰动的泥炭样品,同时查明了泥炭层的厚度。通过试验初步探索了采用轻便钻机配套振动冲击钻进工艺进行泥炭调查取样的有效性。浅层取样钻探作为泥炭调查取样的一种直接有效的技术手段,可以有效地提高泥炭调查效率和精度,为准确评价泥炭储量数据提供可靠的钻探技术服务支撑。