Peat-forming Environments Research Articles

Peat-forming history of the ancestral Souris mire (Palaeocene), Ravenscrag Formation, southern Saskatchewan, Canada

Analysis of the Palaeocene Souris Lignite (northern Williston Basin) using coal petrology and palynology reveals the existence of seven different mire types forming six cycles of varying thickness and composition. The order of mire types within the individual cycles allows an idealized mire type succession to be defined. The principle factor driving the idealized mire type succession is decreasing water depth within the peat-forming environment (terrestrialization), which leads to an increase in species diversity and a change in floral character from ferns→ angiosperms→ gymnosperms. Increases in water depth are the primary agent responsible for the termination of individual cycles in the ancestral Souris mire. Changes in nutrient status of the mire may also promote major changes in the floral assemblage, contributing to cycle termination. Comparison of densinite:ulminite ratios for the central part of the Souris seam shows an overall decrease in the degree of humification south-westward, indicating increased subsidence towards the Williston Basin centre, where seam partings are more common. Fern-rich mire types dominate throughout most of the sampled part of the Souris seam and such mires have been interpreted as representing transitional stages in both modern and Tertiary peat-forming environments. Previous analysis of other parts of the Souris seam has revealed areas dominated by Taxodium forest mires, representing more stable environments. The co-existence of transitional and stable environments suggests that the ancestral Souris mire may have been deposited during the onset of the closing stages of Palaeocene peat formation in the northern part of the Williston Basin.

Facies studies of bituminous coals in Poland

Polish bituminous coal basins are associated exclusively with Carboniferous deposits, differing in origin and geological structure. This paper presents only short review of papers of Polish authors on coal facies studies of Carboniferous coals occurring in the Lower Silesian Coal Basin (LSCB), Upper Silesian Coal Basin (USCB) and Lublin Coal Basin (LCB) of Poland. Facies investigations of Carboniferous coals of Poland have been in progress over 20 years. The results of these studies have provided new information on such subjects as: (i) recognition of main depositional conditions in paleomires, (ii) determine prevailing paleoplant communities, (iii) appraisal of peat-forming environment reconstruction-types and characteristics of paleomires. These facies analyses are connected to results of such studies as: pure coal petrology, using maceral and microlithotype composition as parameters of the environment of coal deposition, combined results of petrological, palynological and sedimentological studies.

Coal facies studies in Hungary: a historical review

The objective of this short summary is to provide an overview on the work of Hungarian geoscientists, who published their results mainly in Hungarian language. The aim of their studies was to understand coal formation and to make reconstruction on the different peat-forming environments. In addition to coal petrographical methods other investigation tools, such as palynology, sedimentology, and organic geochemistry were applied to understand the formation, accumulation and diagenesis of land derived organic matter in different geological realms and environments.

High latitude meteoric δ18O compositions: Paleosol siderite in the Middle Cretaceous Nanushuk Formation, North Slope, Alaska

Siderite-bearing pedogenic horizons of the Nanushuk Formation of the North Slope, Alaska, provide a critical high paleolatitude oxygen isotopic proxy record of paleoprecipitation, supplying important empirical data needed for paleoclimatic reconstructions and models of “greenhouse- world” precipitation rates. Siderite δ 18 O values were determined from four paleosol horizons in the National Petroleum Reserve Alaska (NPR-A) Grandstand # 1 Core, and the values range between −17.6‰ and −14.3‰ Peedee belemnite (PDB) with standard deviations generally less than 0.6‰ within individual horizons. The δ 13 C values are much more variable, ranging from −4.6‰ to +10.8‰ PDB. A covariant δ 18 O versus δ 13 C trend in one horizon probably resulted from mixing between modified marine and meteoric phreatic fluids during siderite precipitation. Groundwater values calculated from siderite oxygen isotopic values and paleobotanical temperature estimates range from −23.0‰ to −19.5‰ standard mean ocean water (SMOW). Minor element analyses show that the siderites are impure, having enrichments in Ca, Mg, Mn, and Sr. Minor element substitutions and Mg/Fe and Mg/(Ca + Mg) ratios also suggest the influence of marine fluids upon siderite precipitation. The pedogenic horizons are characterized by gleyed colors, rare root traces, abundant siderite, abundant organic matter, rare clay and silty clay coatings and infillings, some preservation of primary sedimentary stratification, and a lack of ferruginous oxides and mottles. The pedogenic features suggest that these were poorly drained, reducing, hydromorphic soils that developed in coal-bearing delta plain facies and are similar to modern Inceptisols. Model-derived estimates of precipitation rates for the Late Albian of the North Slope, Alaska (485–626 mm/yr), are consistent with precipitation rates necessary to maintain modern peat-forming environments. This information reinforces the mutual consistency between empirical paleotemperature estimates and isotope mass balance models of the hydrologic cycle and can be used in future global circulation modeling (GCM) experiments of “greenhouse- world” climates to constrain high latitude precipitation rates in simulations of ancient worlds with decreased equator-to-pole temperature gradients.

Holocene evolution of the western Orinoco Delta, Venezuela

Research Article| April 01, 2003 Holocene evolution of the western Orinoco Delta, Venezuela Andres Aslan; Andres Aslan 1Department of Physical and Environmental Sciences, Mesa State College, Grand Junction, Colorado 81501-7682, USA Search for other works by this author on: GSW Google Scholar William A. White; William A. White 2Bureau of Economic Geology, John A. and Katherine G. Jackson School of Geosciences, University Station, Box X, University of Texas, Austin, Texas 78713-8924, USA Search for other works by this author on: GSW Google Scholar Andrew G. Warne; Andrew G. Warne 3U.S. Geological Survey, GSA Center, 651 Federal Drive, Guaynabo, Puerto Rico 00965-5703, USA Search for other works by this author on: GSW Google Scholar Edgar H. Guevara Edgar H. Guevara 4Bureau of Economic Geology, John A. and Katherine G. Jackson School of Geosciences, University Station, Box X, University of Texas, Austin, Texas 78713-8924, USA Search for other works by this author on: GSW Google Scholar GSA Bulletin (2003) 115 (4): 479–498. https://doi.org/10.1130/0016-7606(2003)115<0479:HEOTWO>2.0.CO;2 Article history received: 11 Jan 2002 rev-recd: 04 Sep 2002 accepted: 04 Nov 2002 first online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Andres Aslan, William A. White, Andrew G. Warne, Edgar H. Guevara; Holocene evolution of the western Orinoco Delta, Venezuela. GSA Bulletin 2003;; 115 (4): 479–498. doi: https://doi.org/10.1130/0016-7606(2003)115<0479:HEOTWO>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The pristine nature of the Orinoco Delta of eastern Venezuela provides unique opportunities to study the geologic processes and environments of a major tropical delta. Remote-sensing images, shallow cores, and radiocarbon-dating of organic remains form the basis for describing deltaic environments and interpreting the Holocene history of the delta.The Orinoco Delta can be subdivided into two major sectors. The southeast sector is dominated by the Rio Grande—the principal distributary—and complex networks of anastomosing fluvial and tidal channels. The abundance of siliciclastic deposits suggests that fluvial processes such as overbank flooding strongly influence this part of the delta. In contrast, the northwest sector is represented by few major distributaries, and overbank sedimentation is less widespread relative to the southeast sector. Peat is abundant and occurs in herbaceous and forested swamps that are individually up to 200 km2 in area. Northwest-directed littoral currents transport large volumes of suspended sediment and produce prominent mudcapes along the northwest coast.Mapping of surface sediments, vegetation, and major landforms identified four principal geomorphic systems within the western delta plain: (1) distributary channels, (2) interdistributary flood basins, (3) fluvial-marine transitional environments, and (4) marine-influenced coastal environments. Coring and radiocarbon dating of deltaic deposits show that the northern delta shoreline has prograded 20–30 km during the late Holocene sea-level highstand. Progradation has been accomplished by a combination of distributary avulsion and mudcape progradation. This style of deltaic progradation differs markedly from other deltas such as the Mississippi where distributary avulsion leads to coastal land loss, rather than shoreline progradation. The key difference is that the Orinoco Delta coastal zone receives prodigious amounts of sediment from northwest-moving littoral currents that transport sediment from as far away as the Amazon system (∼1600 km).Late Holocene progradation of the delta has decreased delta-plain gradients, increased water levels, and minimized overbank flooding and siliciclastic sedimentation in the northwest sector. These conditions, coupled with large amounts of direct precipitation, have led to widespread peat accumulation in interdistributary basins. Because peat-forming environments cover up to 5000 km2 of the delta plain, the Orinoco may be an excellent analogue for interpreting ancient deltaic peat deposits. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Tuffaceous deposition in the Newcastle Coal Measures: challenging existing concepts of peat formation in the Sydney Basin, New South Wales, Australia

The Late Permian Newcastle Coal Measures of the northern Sydney Basin, Australia, contain numerous volcanic ash deposits occurring as both interseam tuffs and intraseam tonsteins. These tuffaceous units have been used to correlate seams of the Newcastle Coal Measures with the stratigraphically equivalent Wollombi Coal Measures in the adjacent Hunter Coalfield. Such correlations across the width of the northern Sydney Basin are based not on only tuffaceous markers, but also on chemical and maceral profiles within individual coal plies and carbonaceous shales. These correlations imply a lateral continuity of the peat-forming environment previously unrecognised in the Sydney Basin, and have led directly to the discovery of a new open-cut coal resource in the Hunter Coalfield. The uniform distribution of tonsteins and coal plies also challenges many existing concepts of peat formation. It is proposed that the peat surface was predominantly below the water table, and the term “lowered mire” is proposed to describe this environment. A subaqueous peat surface would protect thin volcanic ash deposits from subsequent redistribution by rainfall and surface runoff, and is consistent with a lack of tree preservation within the intraseam tonsteins. It is envisaged that trees were generally restricted to the peat margins, and to specific horizons where the peat surface was exposed by a fall in the water table. Long-distance correlations of tonsteins also contradict models of coal formation incorporating lateral peat migration, where time constant horizons such as tonsteins should transgress the coal seam profile over large distances.

Fern ecological implications from the Lower Jurassic in Western Hubei, China

The Lower Jurassic Hsiangchi Formation in western Hubei, China is well known for its abundant and diverse fossil ferns, including Marattiaceae, Osmundaceae, Matoniaceae, Dipteridaceae and Dicksoniaceae. Through recent collections and investigation of the fossil plants in this area, an autochthonous/hypoautochthonous fern community has been recognised from the upper part of the Hsiangchi Formation in Zigui, Hubei. This community is dominated by the matoniaceous ferns of the genus Phlebopteris; Dipteridaceous ferns mainly characterised by Dictyophyllum rank second in abundance. Marattiaceae ( Marattia) and Osmundaceae ( Todites and Cladophlebis) are often dispersed spatially among the dominant ferns, whereas the small and slender herbaceous Dicksoniaceae, characterised by Coniopteris, are sparsely distributed within the community. This fern community colonised the fluviatile peat-forming environment and indicates a tropical to subtropical climate with warm and humid conditions, which is favourable for the peat accumulation. It is also a representative fern community recognised from the Southern Floristic Province in China during late Early Jurassic period.

Characterization and quantification of inorganic constituents of tropical peats and organic-rich deposits from Tasek Bera (Peninsular Malaysia): implications for coals

Since the Carboniferous, tropical latitudes have been the site of formation of many economic coal deposits, most of which have a restricted range of mineralogical composition as a result of their depositional environment, climatic conditions, and diagenesis. Mineralogical and microscopic investigations of tropical peats from Tasek Bera, Peninsular Malaysia, were performed in order to better understand some of these factors controlling the nature, distribution and association of inorganic matter in peat-forming environments. Distribution and nature of the inorganic fraction of peat deposits give insight into the weathering conditions and detrital input into the mire system. Because the inorganic composition of peat deposits is determined by plant communities, height of water table, and climate, the results of the quantitative and qualitative analysis can be used to reconstruct palaeoclimatic conditions. Tasek Bera is a peat-accumulating basin in humid tropical Malaysia with organic deposits of low- to high-ash yield and thus representative of many ancient peat-forming environments. Clay minerals dominate the mineralogical composition of the peat and organic-rich sediments, while quartz and clays dominate the underlying siliciclastic deposits. Kaolinite is the most abundant clay mineral in the organic deposits with minor amounts of illite and vermiculite. Particle size analyses indicate that >50% of the inorganic detrital fraction is <2 μm. Most detrital quartz grains range in size from fine silt to fine sand. The fine sand fraction accounts for a maximum of 5 wt.% of the inorganic constituents. In addition, abundant biogenic and non-biogenic, Al- and Si-rich amorphous matter occur. In the ombrotrophic (low-nutrient) environment, biogenic inorganic material contributes up to >75% of the ash constituents. As a consequence, the vegetational communities make an important contribution to the inorganic and overall ash composition of peats and coals. The ash content of the often inundated peat consists on average of 10% opaline silica from diatoms and sponge spicules, while the ash of the top deposits may have up to 50% biogenic silica. Hence, Al- and Si-hydroxides and the opaline silica from diatoms and sponges represent a large repository of Al and Si, which may form the basis of mineral transformation, neoformation and alteration processes during coalification of the peat deposits. As a result, most coal deposits from paleotropical environments are anticipated to have little to no biogenic inorganic material but high amounts of secondary clays, such as kaolinite (detrital kaolinite, resilisified kaolinite, or desilisified gibbsite) or illite, and various amounts of detrital and authigenetic quartz.

Comparing maceral ratios from tropical peatlands with assumptions from coal studies: do classic coal petrographic interpretation methods have to be discarded?

Petrographic investigations of tropical peat deposits from the Tasek Bera Basin, Malaysia, show that petrographic methods can contribute valuable information about paleoecological settings of mire deposits. Comparing modern peat-forming environments and the pre-maceral composition of peat samples allows the reconstruction of paleoecological conditions, such as floral composition, fires, microbial activity, etc., and gives insight into paleodepositional environments. In the past, maceral ratios of coals have been used to interpret paleodepositional settings of coal deposits. Such a procedure assumes that coal texture and coal maceral composition are dictated solely by the depositional environment, and thus different depositional environments should be clearly discriminated based on maceral ratios. In the modern peat deposits of Tasek Bera, divergent petrographic results occur in similar depositional environments, hence, poor correlation occurs between the petrography, the degree of decomposition, and the depositional environment. Furthermore, from the time of peat deposition, peat is subject to considerable alteration. During subsequent diagenesis, preservation of structured and strongly altered material, such as inertinite, gelified material or funginite, is favoured and results in biased coal maceral compositions. Because maceral indexes in modern peat studies are of little utility in the reconstruction of paleoenvironmental settings, it follows that coal maceral indexes should not be utilized in the future to interpret paleodepositional environments of coals.

Drowning of a nearshore peat-forming environment, Atane Formation (Cretaceous) at Asuk, West Greenland: sedimentology, organic petrography and geochemistry

The Cretaceous Atane Formation, Nuussuaq basin, West Greenland, is dominated by non-marine sandstones, shales, coals, and delta-front deposits. Marine incursions are frequent, however, and near Asuk, Disko, a coal seam is encased in shallow marine deposits. Notable changes in both petrography and geochemistry occur through the seam. At the base and top of the seam, the proportions of inertinite and liptinite increase at the expense of the huminite maceral group, and within all maceral groups proportions of detrital macerals increase. Geochemical changes include systematic variations in TOC, TS, n-alkane, acyclic isoprenoid, aromatic hydrocarbon, and di- and triterpenoid biomarkers, which include a number of rearranged hopanes and hopenes, and six isomers of 28,30-bisnorhopane. The variations reflect diagenetic changes related to the availability of clay, as well as changes in depositional environment going from shallow marine conditions, through fresh water mire back to open water conditions and to the eventual return of shallow marine conditions, shown by the occurrence of delta-front deposits containing Ophiomorpha nodosa trace fossils c. 50 cm above the top of the coal seam.

Sulphur and iron geochemistry of Holocene coastal peats (NW Germany): a tool for palaeoenvironmental reconstruction

A drill core from the marshlands of NW Germany covering the entire Holocene was analysed at high-resolution by geochemical (XRF, Cirm-MS) and microfacies methods (diatoms, thin sections, SEM) in order to provide information about the palaeoenvironmental development. In addition, microbial experiments were carried out with sulphate-reducing bacteria (SRB) and cellulose fermenting fungi in seawater using peat as substrate. The core contains an intercalated reed peat layer (2.73–3.02 m) and a basal peat (5.78–6.42 m). The basal peat consists in the lowest part of fen woodland and raised bog peat, while the upper part is formed by a reed peat bed. The peat layers are characterised by a distinct enrichment of pyrite with negative bulk sediment δ 34S values (av. −11.5‰, range −2.6 to −26.7‰) reflecting microbial sulphate reduction in some peat intervals under almost open system conditions with respect to the input of seawater sulphate. Pyrite occurs exclusively with framboidal texture in close vicinity to the organic matter which indicates localised pyrite formation at the decay site in microenvironments with high concentrations of dissolved Fe. Microbial experiments reveal that peat does not represent an appropriate substrate for SRB and that SRB have to rely on the preceding decomposition of peat by other microorganisms in microenvironments. The total sulphur content of the peat layers averages to 7.8 wt% with a maximum value of 28.2 wt% unusually found within the basal peat at the transition of fen woodland and raised bog peat. The pyrite enrichments can be explained by two different scenarios which are related to the intensity of the sea-level rise. The first scenario applies to a moderate sea-level rise and is decisive for the reed peats where pyrite formation coincides with peat growth. A brackish zone is assumed for the peat-forming environment which is influenced by iron-rich freshwater and sulphate-rich seawater. As the freshwater forms the major Fe source the amounts of pyrite increase to a certain degree with decreasing salinity in this environment. The palaeosalinity is estimated by the investigation of littoral and pelagic diatoms. The second scenario applies to the extensive pyrite formation within the basal peat at the transition of fen and bog peat. This pyrite was likely formed after peat growth favoured by a steep sea-level rise. Thin sections of this peat interval reveal clastic layers (1–3 mm) with completely pyritised interfaces. As these clastic layers contain marine pelagic diatoms (e.g. Paralia sulcata) we propose that they are caused by tidal channel activities during a phase of a steep sea-level rise. The marine incursion led to a partial buoyancy of the basal peat at weak transition zones, i.e. the transition from fen to bog peat. As a result of the bouyancy, marine suspended particulate matter can be introduced laterally in-between the peat sections. When the peat settles down a clastic layer remains whose interface with the peat may have favoured the inflow of waters of higher salinity. Therefore, an enhanced formation of pyrite was possible due to the combination of sulphate-rich ground water and iron-rich peatland waters.

Mineralogical and elemental variation of coal from Alberta, Canada: an example from the No. 2 seam, Genesee Mine

Mineralogy and elemental contents were determined on 18 samples from a vertical profile of the No. 2 seam, Genesee mine, AB. The samples analyzed consist of coal, coaly shale, shaly coal, carbonaceous shale, shale, mudstone and siltstone. Proximate analysis was determined on all samples. Elemental analyses were determined by instrumental neutron activation analysis (INAA) for all elements except As, B, Cd, Hg, Mo, Pb, Se (Atomic Absorption) and B, Ba, Be, Co, Cr, Cu, Li, Mn, Nb, Sr and V (inductively coupled plasma-emission spectroscopy, ICP-ES). Samples were low temperature ashed (LTA), X-ray diffraction (XRD) and X-ray fluorescence (XRF) were used to determine quantitative major mineralogy. Accessory mineralogy was determined with Scannining Electron microscope/energy dispersive X-ray analyzer (SEM/EDX) on four samples. In general, the coals in the Genesee mine are within the low end of the range for trace element contents given by Swaine [Swaine, D.J., 1990. Trace Elements in Coal. Butterworths, London, 278 pp.] for most coals. High contents of Cr (9–2620 ppm) and Ni (1–1440 ppm) can be related to an increased amount of a Cr–Ni–Fe oxide (chromite–magnetite?) likely derived from ultrabasic diatremes in the Golden-Columbia Icefields, BC area. The No. 2 seam of the Genesee mine can be divided into two geochemical cycles on the basis of mineralogy, trace element contents and rare earth element (REE) behavior. Cycle I consists of quartz, calcite and kaolinite, lower trace element contents, REE slightly enriched in high rare earth elements (HREE), and thick coal with few partings. Cycle II consists of quartz, calcite, kaolinite, illite, mixed layer and/or expandable lattice clays, feldspar, gypsum, calcium aluminum sulfate hydrate, clinoptilolite, calcite and diopside, higher trace element contents, REE slightly enriched in light rare earth elements (LREE) and thin coal with a greater frequency of partings. The differences between the two geochemical cycles can be accounted for by a decreasing stability of the peat-forming environment resulting from an increasing fluvial influence and volcanogenic input.

APPLICATIONS OF MODERN AND ANCIENT GEOLOGICAL ANALOGUES IN CHARACTERISATION OF FLUVIAL AND FLUVIAL-LACUSTRINE DELTAIC RESERVOIRS IN THE COOPER BASIN

Reservoir characterisation in fluvial and fluvial- lacustrine delta successions is enhanced by the use of appropriate modern and ancient analogues to understand subsurface reservoir architecture and to help build appropriately scaled reservoir models. Two case studies of reservoir characterisation in the Cooper Basin are used to illustrate the value of analogues. Firstly the Late Permian Toolachee Formation crevasse splay reservoirs of the Cooper Basin, southwest Queensland are outlined, and analogues from the Ob River in Western Siberia illustrate the relative scale of crevasse splay deposits within avulsion belts in a cool-temperate peat-forming environment. The South Blackwater coal mine in the Permian Bowen Basin is used as an analogue to quantify the 3D geometry and reservoir architecture of crevasse splays and to highlight subsurface reservoir heterogeneity.Secondly, the Early Permian Epsilon Formation shallow water lacustrine delta reservoirs are outlined, and analogues from the extant geometry of the distributary channels and relict mouth bar deposits from the fluvial dominated Neales Delta in Lake Eyre are used to interpret flow rate decline trends and probable reservoir architecture. The subsurface Tertiary lacustrine deltaic complex of the Sirikit Field from the Phitsanulok Basin, central Thailand, is selected as an ancient analogue for the multistorey reservoirs developed within amalgamated mouth bar complexes intersected in the lower Epsilon Formation.

Coal geology and coal quality of the Miocene Mugla basin, southwestern Anatolia, Turkey

This work focuses on the relationship between the coal geology and coal quality of the Miocene Mugla basin, Southwestern Anatolia, Turkey. To this end, detailed petrographical, mineralogical and geochemical studies were performed on composite profile samples from the nine coal fields in the Mugla basin (Alatepe, Bagyaka, Bayir, Çakiralan, Ekizköy, Eskihisar, Hüsamlar, Sekköy and Tinaz coal fields). The Mugla lignite is a high ash (from 16 to 56%) and sulphur (from 2.1 to 5.7%) lignite which is petrographically characterised by a high huminite content, mainly gelinite macerals. The mineral matter of the studied lignite samples is made up mainly of clay minerals and quartz, with the exception of the Sekköy and Ekizköy lignites, in which calcite is the dominant mineral phase with minor amounts of quartz, clay minerals, pyrite and gypsum and traces of aragonite. Syngenetic opal is also frequently identified in these samples. The differentiation of these two types of lignite with specific mineralogical patterns is attributed to the contemporaneous development of peatlands with a high detrital input, dominated by the quartz and clay mineral setting, and peatlands with low detrital supply and a dominant carbonate-rich lacustrine environment. The higher water table of the latter allowed the precipitation of micritic carbonates and the development of lakes with abundant mollusc fauna. This differentiation is also evidenced by the geochemical data. Thus, the Sekköy, Ekizköy, Hüsamlar, Bayir and Alatepe lignites are characterised by relatively low Al and Fe contents (<1.4%) and high sulphur contents (4.2 to 5.7%). In addition Sekköy and Ekizköy show relatively high contents of Ca (6.3–7.1% compared to 1.6–3.8% in the other lignites). All the lignite samples studied are characterised by relatively high Mo and U contents when compared with the worldwide averages of trace elements in coal. Relatively high alkaline syngenetic conditions of the peat-forming environment of the Mugla coal are deduced from the following mineralogical, petrographical and geochemical evidence: (a) the precipitation of syngenetic opal (dissolution of quartz and re-precipitation as opal) and calcite; (b) minor and very early syngenetic sulphide precipitation (only framboidal and euhedral pyrite); (c) high bacterial activity, typical of high pH conditions, inferred from low preservation of tissue structures; (d) preservation of aragonite gastropod shells; and (e) the anomalous enrichment of U, Mo and W. A key result of the study of Mugla limnic coals (at least of the Sekköy and Ekizköy coal fields) is that a major influence was exerted on the early diagenetic evolution of the coal by the hydrochemistry of the lacustrine waters. This hydrochemistry was largely linked to the lithology of the surrounding source rock areas although the final evolutionary trend of the solute composition in the lake waters, characterized by very high carbonate and sulphate contents, was largely enhanced by the endorheic river drainage system and the arid–semiarid paleoclimatic situation under which organic matter accumulation took place.

Illitization in a Paleozoic, peat-forming environment as evidence for biogenic potassium accumulation

Potassium enrichment is common in surface horizons of many paleosols and has been attributed to the formation of authigenic illite from smectites during burial diagenesis. In such cases, the presence of primary smectite is key to the illitization process, which then results in potassium enrichment as a byproduct. Potassium enrichment in paleosols where no primary smectite was present, however, requires a different process of accumulation. A Lower Pennsylvanian, tropical Ultisol from the Southern Anthracite Field in Pennsylvania is enriched in potassium in the surface horizon and formed in an environment unfavorable for smectite accumulation. Kaolinite dominates clay mineral fractions of soils that form in such highly weathering environments. In the absence of primary smectite to scavenge potassium during illitization, there should be no potassium enrichment during burial diagenesis. However, in Lykens Valley paleosol, the pattern of potassium concentration, organic matter distribution and authigenic illite growth suggests that organic matter may have provided an important source of potassium for illite formation. Illitization of kaolinite in the organic-rich surface horizon is complete but, illite coexists with kaolinite in the B horizon. Within the paleosol matrix, illitization is more complete in areas of high organic concentration where organic fragments often have illite haloes with illite whorls growing from their edges. We propose that the potassium enrichment both in the soil profile and in the overlying coal is the result of the luxury uptake of potassium by peat-forming plants (nutrient intake at rates exceeding metabolic requirements). Further, potassium immobilized by adsorption on the peat provided interlayer cations for illite authigenesis to begin. If, as we suggest, luxury nutrient uptake during peat formation sequestered sufficient potassium to promote later illite formation, the pattern and extent of illitization within the paleosol profile reflects early biogenic nutrient accumulation. Thus, illite, in some paleosols, may represent fossil evidence for a biological process: the luxury uptake of potassium.

Peat-forming environments of Westphalian A coal seams from the Lower Silesian Coal Basin of SW Poland based on petrographic and palynologic data

The petrographic and palynologic compositions of coal seams of the Żacler formation (Upper Carboniferous, Westphalian A) from northwestern and southeastern part of the Lower Silesian Coal Basin (LSCB) were examined. Coals studied are highly volatile bituminous coal, where R o ranges from 0.91% to 1.09%. Seam 430 from the northwestern part of the basin contains high vitrinite percentage with rather low inertinite and liptinite contents, while percentage of mineral matter is variable. This petrographic composition is associated either with a predominance of Lycospora in miospore assemblage, or with a miospore assemblage of mixed character. The abundance of Lycospora reflects vegetation composed of the arborescent lycopsids while the mixed miospore assemblage is connected with diverse palaeoplant communities, namely, arborescent lycopsids, calamites and ferns. Seams 409 and 412/413 from the southeastern part of the LSCB are rich in inertinite and liptinite, while the vitrinite content is moderate. Their characteristic feature is the occurrence of a diagnostic crassisporinite (densosporinite). Amount of the mineral components in these coals is very low. Densosporites and related crassicingulate genera are main components of these miospore assemblages and were produced by herbaceous and/or sub-arborescent lycopsids. These petrographic and palynologic features were the basis for distinguishing three maceral–miospore associations: an arborescent lycopsid and mixed associations, occurring in the seam 430 and a herbaceous and/or sub-arborescent lycopsid association which was recorded in seams 409 and 412/413. The first two assemblages are interpreted as having been deposited in a planar rheotrophic mire, whereas the herbaceous and/or sub-arborescent lycopsid association is thought to have developed in an ombrotrophic, domed mire.

Geological factors influencing the concentration of trace elements in the Philippi peatland, eastern Macedonia, Greece

Six peat samples obtained from the Holocene and the Weichselian of the Philippi peat deposit, eastern Macedonia, Greece, were analyzed for 48 trace elements by Inductively Coupled Plasma–Mass Spectrometry (ICP–MS). The ash contents of these samples were also determined. Most of the trace elements are associated with the minerals in the peat, while Ge, Mo, Pb, Se, Ta, Tl, U, and W display a greater affinity with the organic matter. Compared with crustal averages (Clarke concentrations), the Philippi peat is enriched in some elements (Ag, As, Au, Cd, Mo, Se, Te, U, and W) because of the respective mineralizations in the area. The Philippi peat is also enriched in Cr, Cu, Mo, Pb, Sc, Sn, T, V, Y, and Zn in comparison with typical fen peats, as well as in As, Cr, Mo, Se, and U in comparison with typical coals. Climatic and hydrogeological conditions strongly influenced the peat-forming environment resulting in a differentiation between Holocene and Weichselian peat. Generally, the Holocene peat contains lower concentrations of trace elements in the northern and southern part of the fen, than the Weichselian one. The opposite trend is observed in the fen area close to the western basin margins.

Petrographic changes induced by artificial coalification of peat: comparison of two planar facies (Rhizophora and Cladium) from the Everglades-mangrove complex of Florida and a domed facies (Cyrilla) from the Okefenokee Swamp of Georgia

Petrographic changes during coalification of three peat samples were investigated by artificial coalification experiments using a semi-open reactor system. Compressions of from 83 to 88% produced dark brown to black, shiny, flattened pellets exhibiting microscopic banding. Overall amounts of compression inversely correlated with the framework to matrix ratios ( F M ); although, certain tissue fragments remained relatively uncompressed due to the presence of tanniniferous cell fillings and also, hypothetically, to the presence of colorless plant secretions or gelified wall materials that were present in the cells but only recognizable after a change in color during coalification. The most distinct microscopic banding (longest and widest bands) developed in samples of the dome-formed peat facies, which had the highest framework to matrix ratios of any type and the greatest contents of surface litter composing the framework (i.e. highest S N ratio). The planar, root-dominated, Rhizophora facies showed the greatest change in microbanding character during coalification; in that, the numerous lens-like bands produced by the compressed roots were very distinct at the 60°/2100 psi (121.4 kg/cm 2) stage but nearly disappeared at the 175°/5000 psi (289.1 kg/cm 2)) stage. This is explained as a result of differences in rates of coalification of the different telinitic precursors in the roots (multilinear vitrinization) and could explain why roots are significant components of many modern peats (and ancient coal ball concretions) but are difficult to recognize in bituminous coals. Similarly, separation of cuticles from leaves in modern peat-forming environments, due to irreversible shriveling and subsequent enhanced microbiological decay, partially explains why leaf remains are also difficult to recognize in most coals, even those with abundant cutinites. Microcracks developed in all pellets, with dominant orientations of cracks being either perpendicular to induced banding or horizontal to it. Minute, vertical microcracks (interpreted as ‘dewatering’ features) were observed primarily in gelinitic bands, especially in the most fire-prone, Cladium coal facies; but, these rarely extended into juxtaposed microlithotypes as did most of the larger vertical cracks. Horizontal cracks tended to form at microband boundaries. Almost all humotelinitic and humocollinitic precursors showed some changes in color during artificial coalification, with humotelinites exhibiting less or slower changes than humocolinites or humodetrinites (finer-grained matrix material). Additionally, nearly all dark brown, degraded tissues in the peats became dark orange or red during coalification; but, many of these tissue masses were observed to contain significant amounts of minute inertinite derived from microorganisms (‘pseudomicrinite’) that only became prominent after coalification and subsequent change in color of surrounding macerals. Fusinite precursors were only found in the fire-prone Cladium facies; and, although, the coalified, doming-generated, Cyrilla facies exhibited evidence of significant drying events (i.e. occasional bands or parts of bands containing significant pseudomicrinites, macrinites and sclerotinites), it was dominated by huminitic (vitrinitic) components. Liptinites were most common in the coalified, dome-formed, Cyrilla facies and displayed a slight qualitative increase in red/green fluorescence during coalification and some possible flow of components into nearby cracks. Changes in mean random reflectance of huminitic macerals, although still requiring more data and only measured to the 60°C/2100 psi (121.4 kg/cm 2) level, indicated increasing directions of change during artificial coalification, with humocollinitic macerals progressing from an average of about 0.21% to 0.32% and humotelinitic macerals (which consistently had lower inherent reflectances in the peats) progressing from 0.15 to 0.25%. The above petrographic results, along with previously reported chemical results, all suggest that the methods that we have used in these experiments have produced changes that might reasonably be expected to occur during natural coalification (despite the fact that we have speeded up the process). Although more work needs to be done to verify and refine these results and to establish a correlation between these artificial ‘coalification steps’ and true coalification, the new observations and conclusions from these studies might still be helpful in constructing models to predict or interpret coal seam characteristics and to establish the timing and release-potential of gaseous or liquid hydrocarbons from coals.

The origin and distribution of HAPs elements in relation to maceral composition of the A1 lignite bed (Paleocene, Calvert Bluff Formation, Wilcox Group), Calvert mine area, east-central Texas

The origin and distribution of twelve potentially Hazardous Air Pollutants (HAPs; As, Be, Cd, Cr, Co, Hg, Mn, Ni, Pb, Sb, Se, and U) identified in the 1990 Clean Air Act Amendments were examined in relation to the maceral composition of the A1 bed (Paleocene, Calvert Bluff Formation, Wilcox Group) of the Calvert mine in east-central Texas. The 3.2 m-thick A1 bed was divided into nine incremental channel samples (7 lignite samples and 2 shaley coal samples) on the basis of megascopic characteristics. Results indicate that As, Cd, Cr, Ni, Pb, Sb, and U are strongly correlated with ash yield and are enriched in the shaley coal samples. We infer that these elements are associated with inorganic constituents in the coal bed and may be derived from a penecontemporaneous stream channel located several kilometers southeast of the mining block. Of the HAPs elements studied, Mn and Hg are the most poorly correlated to ash yield. We infer an organic association for Mn; Hg may be associated with pyrite. The rest of the trace elements (Be, Co, and Se) are weakly correlated with ash yield. Further analytical work is necessary to determine the mode of occurrence for these elements. Overall, concentrations of the HAPs elements are generally similar to or less than those reported in previous studies of lignites of the Wilcox Group, east-central region, Texas. Petrographic analysis indicates the following ranges in composition for the seven lignite samples: liptinites (5–8%), huminites (88–95%), and inertinites (trace amounts to 7%). Samples from the middle portion of the A1 bed contain abundant crypto-eugelinite compared to the rest of the samples; this relationship suggests that the degradation of plant material was an important process during the development of the peat mire. With the exception of Hg and Mn, relatively low levels of the HAPs elements studied are found in the samples containing abundant crypto-eugelinite. We infer that the peat-forming environment for this portion of the coal bed was very wet with minimal detrital input. Relatively high concentrations of crypto-humotelinite were found in samples from the top and base of the coal bed. The presence of abundant crypto-humotefinite in this part of the coal bed suggests the accumulation of wood-rich peat under conditions conducive to a high degree of tissue preservation in the peat mire. Although several of the trace elements (Be, Co, Ni, and Sb) exhibit enrichment in these samples, they are not necessarily chemically associated with humotelinite. We infer that these elements, with the exception of Be, are possibly associated with deposition of the roof and floor rock of the coal bed; however, further analytical work would be necessary to confirm this hypothesis. Beryllium may have an organic origin.

Striking liptinitic bark remains peculiar to some Late Permian Chinese coals

An unusual liptinite coal component has been reported in the Chinese literature over the past sixty years. It has been described as a maceral in the Chinese National Standard (1991), but it has not been named internationally. In Chinese literature it is called “barkinite”, on the basis of its morphological features and because it is believed to have originated as bark tissue. “Barkinite” occurs in Late Permian, marine-influenced coals and is best represented in the Changguang, Leping and Shuicheng Basins of southern China. The material originates from plant periderm or the bark of higher plants. However, “bark” contains a variety of substances, including resin and suberin, which are recognised as the precursors of the resinite and suberinite macerals. “Barkinite” is distinguished by (i) its thickness; individual pieces can be more than ten cells thick and several centimetres long and (ii) it fluoresces strongly at 0.6% vitrinite reflectance and loses its fluorescence at about 1.1% vitrinite reflectance. The reporting of “barkinite” from only Chinese coals may be due to its origin from Lepidodendron and Psaronius flora, which was common in the Northern Hemisphere during the Carboniferous, but which was isolated to China by the Late Permian. It is proposed that the remnant flora evolved into unique forms in China by the Late Permian. Lepidodendron and Psaronius remains, coupled with a strongly marine-influenced, peat-forming environment have given rise to “barkinite” and to its restricted distribution.