Arborescent Lycopods Research Articles

A reassessment of the leafy shoots of Pennsylvanian-age arborescent lycopods

ABSTRACT The known fossil-species of upper Carboniferous (Pennsylvanian) arborescent lycopod leafy shoots are re-examined. The leaf characters used in species characterisation include size (length and breadth), angle of departure from the stems and the overall shape (straight, curved or S-shaped). Sometimes leafy shoots can be directly related to known species of stems that are defined on their surface features of leaf cushions as in Lepidodendron, Lepidophloios and Ulodendron, or directly on the stem surface as in Bothrodendron. They are also assessed in terms of the determinate growth pattern of the plants. A key is given to identify the fossil-species of leafy shoots described here.

Petrology, palynology, and geochemistry of the Pond Creek coal (Pennsylvanian, Duckmantian), Pike County, Kentucky: Overprints of penecontemporaneous tectonism and peat doming

The petrographic, palynologic, and geochemical character of the high volatile A bituminous Pennsylvanian (Bashkerian, Duckmantian) Pond Creek coal was evaluated for a series of mine samples in the Lick Creek and Jamboree 7 ½’ quadrangles in Pike County, Kentucky. In its prime years of production, the Pond Creek coal was among the most important coal resources in the leading coal producing state in the U.S. The thickness and quality of the Pond Creek coal was closely related to its position relative to the northwestward-plunging, N20°E-trending Belfry anticline with the main bed of the coal thinning and the thickness of rock between the latter and the high-S Pond Creek rider bed thinning across the anticline. This suggests that the Belfry anticline and the Pond Creek mire were contemporaneous features, with the rising anticline influencing the lithology and chemistry of the peat. Within the study area, the lower three lithotypes fill the original topography and the next higher lithotype pinching out along the rise towards the anticline. The next three lithologies, a thick bright zone (zone 4 in the nomenclature of this study), a bone coal, and a thinner bright zone are continuous through the study area, although they all thin towards the anticline. The upper durain, the termination of the coal seam, also pinches out towards the anticline. Zone 4 shows a decrease in total vitrinite towards the uppermost bench of the zone, an upwards increase in ash yield, the upwards increase in the floral diversity, and a higher concentration of Mn, CaO, and Ba + Sr in the lower lithologies of the zone. Towards the anticline, there is a greater floral stability within zone 4 compared to the relatively subsiding area to the east. Within the zone 4 bright lithologies, peat growth outpaced the level of the water table, but at the cost of the turnover of the arborescent lycopod forest to a more diminutive flora, the collapse of the ombrogenous peat, and the influx of deeper water and the consequent deposition of the overlying relatively high-ash bone coal.

Palynology, organic petrology and geochemistry of the Bell coal bed in Western Kentucky, Eastern Interior (Illinois) Basin, USA

The Bell coal bed is one of the stratigraphically oldest coals (Atokan, Duckmantian) in the Illinois Basin that has been commercially mined and occurs near the Morrowan-Atokan boundary, which was a time of significant lithologic change in the basin. The Bell coal occurs as a series of discontinuous pods, in contrast to younger (Asturian) coals in the basin that are thicker and more extensive in occurrence. Thirty-two samples of coal and carbonaceous shale, collected from surface mine, outcrop, and drill core locations were analyzed geochemically, petrographically and palynologically to ascertain the origin of the Bell coal bed in western Kentucky.The Bell coal exhibits a great deal of variability in thickness and composition, both temporally and spatially. Based on ash yields, the Bell coal consists of intercalated layers of coal (≤25% ash), impure coal (>25 to <50% ash) and carbonaceous shale (≥50% ash). Sulfur contents vary significantly, from 0.2% to 10.0%. Petrographically, the Bell coal is mainly a high vitrinite coal (>80%, mmf), with telovitrinite occurring more frequently than detrovitrinite and gelovitrinite. Certain layers, however, contain elevated amounts of liptinite and inertinite. Among the inertinite macerals, examples of both fire (e.g., fusinite) and degradation (e.g., macrinite) origin are evident. Samples with elevated amounts of inertinite are commonly, though not exclusively, high in ash, indicating that some of the inertinite may be of allochthonous origin.Palynologically, the Bell coal is dominated by arborescent lycopod spores (avg. >70%), occurring primarily as Lycospora, with some samples containing increased proportions of spores and pollen from other Pennsylvanian plant groups. Samples with more heterogenous palynofloras commonly have elevated ash yields, indicating that some portion of the assemblages may be also of allochthonous origin.Collectively, the Bell coal is interpreted to have formed from a series of small, disconnected paleomires that were planar and topogenous with paleotopography having an influence on peat development. A planar, topogenous origin helps to explain the highly variable ash yields and sulfur contents. Accumulating peat, principally from arborescent lycopod source material, was mainly well-preserved, but punctuated with intervals marked by sediment influx, the development of more heterogeneous palynofloras and degradation and oxidation of the surficial peat by both biologic (decay) and abiotic (fire) processes.

Geochemical, petrographic and palynologic characteristics of two late middle Pennsylvanian (Asturian) coal-to-shale sequences in the eastern Interior Basin, USA

Two coal-to-shale sequences of late Middle Pennsylvanian (Asturian) age from the southern portion of the Eastern Interior (Illinois) Basin, USA were examined geochemically, petrographically and palynologically. The Springfield coal was found to be moderately low in ash yield and high in total sulfur content. Petrographically, the coal is high in vitrinite content and low in liptinite and inertinite. Palynologically, the bed is co-dominated by spores of arborescent lycopod and tree fern affinities. The examination of closely-spaced bench samples revealed vertical species variation within both of these plant groups. Lycospora micropapillata+L. orbicula, both of which were produced by Paralycopodites, are most abundant in basal coal benches, whereas Lycospora granulata, produced by Lepidophloios is the dominant arborescent lycopod spore throughout the rest of the bed. Thymospora pseudothiessenii is the dominant tree fern spore throughout most of the coal, with Laevigatosporites globosus becoming dominant in the top-most coal benches.The Herrin coal bed is also moderately low in ash yield and high in total sulfur content. Unlike the Springfield coal, it contains two distinct inorganic partings that have regional extent. The Herrin coal also has several coal benches with increased ash and sulfur that were not present in the Springfield coal bed. Petrographically, it is dominated by vitrinite, with the partings and high ash coal benches containing more inertinite, and liptinite. Palynologically, the Herrin coal is dominated by arborescent lycopod spores with subdominant tree fern spores. As with the Springfield coal, Lycospora micropapillata+L. orbicula are the dominant arborescent lycopod spores at the base of the coal, with Lycospora granulata dominating the rest of the bed. Granasporites medius, which was produced by Diaphorodendron and Synchysidendron, occurs more frequently in the Herrin coal bed, and are most abundant in, and in proximity to, the two inorganic partings. Tree fern spores are less abundant in the Herrin coal, and do not display any discernable vertical species variation.Collectively, both the Springfield and Herrin coal beds are interpreted to have formed in extensive planar, topogenous mires. Consistently saturated peat conditions throughout the development of both paleomires are indicated by the high vitrinite contents, and prevalence of arborescent lycopods. The deposition of widespread inorganic partings in the Herrin coal represents significant events in peat accumulation, with high ash coal benches representing smaller, more local events.Both of the coals are overlain by black, very organic-rich (avg. TOC±20%) marine shales. The Turner Mine Shale, which directly overlies the Springfield coal, has layers at the coal/shale contact with fairly abundant vitrinite, primarily in the form of vitrodetrinite, near the base of the shale, but the majority of the shale is dominated by the liptinite macerals bituminite, lamalginite and amorphinite. Micrinite is a major organic component of the shale. The Anna Shale, which directly overlies the Herrin coal, is similar in overall maceral composition, but contains less vitrinite, and more solid bitumen and micrinite. Trace element ratios (Ni/Co, V/Cr, V/V+Ni), indicative of paleoredox conditions, indicate that both shales were deposited under mainly dysoxic to suboxic/anoxic conditions. The shales are interpreted to represent a progressively rising water table, caused by an increase in eustatic sea levels. Vitrinite reflectance values in the shales are lower than corresponding values measured from the coal, indicating some degree of vitrinite suppression occurring in the Turner Mine and Anna Shales.

Organic geochemistry of Duckmantian (Pennsylvanian) coals from the Ruhr Basin, western Germany

The molecular composition of 58 Duckmantian Ruhr coals and adjacent sedimentary rocks has been analyzed using organic-geochemical investigations representing a maturity range from 0.74 to 0.98% vitrinite reflectance. In addition eight samples of higher maturity (1.46 to 3.55% vitrinite reflectance) were studied for comparison. The composition of coals depends primarily on plant input into the peat swamps, but also to a large extent on thermal maturity. Several maturity-related parameters have been applied in this study such as MPI, DMAI, and diverse hopanoid-based maturity ratios. Especially diamantane-based parameters proved to be excellent for characterizing high rank samples, whereas hopane- and phenanthrene-based parameters are well-suited for the lower maturity range.Various specific biomarkers reflect the composition of the Duckmantian coals concerning the floral differences and floral shift during the Westphalian. The dominating n-alkanes, hopanes, and bicyclic sesquiterpanes show only marginal differences and reveal a quite homogenous floral composition within the six coal seams. Tetracyclic diterpanes, as approved markers for modern as well as Paleozoic conifers and "pre-gymnosperms", have been identified in all six coal seams, but in low concentration (one order of magnitude lower than bicyclic sesquiterpanes). A slight increase of the tetracyclic diterpane ent-beyerane in the younger seams indicates an increase in abundance of "pre-gymnosperms" (cordaites) during the Duckmantian. Significantly increased proportions of diverse compounds like bicyclic sesquiterpanes (eudesmane) or tetracyclic terpanes clearly testify an origin from higher land plants. The major part of the Duckmantian coal swamps biomass with its vitrinite rich coals originated presumably from barks of arborescent lycopods. High concentrations of hopanes mirror the input of bacterial organic matter and a strong microbial reworking of the deposited terrestrial plant organic matter.

Taxonomy and biostratigraphy of Pennsylvanian to Late Permian megaspores from Shanxi, North China

Well-preserved megaspores are described for the first time from Pennsylvanian to Late Permian strata of the Baode region in Shanxi province, North China. A total of 20 species in 13 genera are described, amongst which one species Biharisporites grosstriletus sp. nov. is new. The other 19 are previously known from the Euramerican and Gondwanan floral provinces, but are described here for first time from the Cathaysian Province. Using first appearances of selected megaspore species and changes in species abundance in the succession, four assemblage zones can be recognised. In ascending order these are the Auritolagenicula renaulti- Setosisporites brevispinosus (RB, Moscovian), the Bentzisiporites margaritatus- Spencerisporites striatus (MS, Kasimovian-Roadian), the Biharisporites grosstriletus (G, Wordian-Capitanian) and the Biharisporites cf. foskettensis (F, Wuchiapingian) assemblage zones. Comparison with already known in situ megaspores indicates that the parent plants of the dispersed megaspores were mainly lycopods and this in turn indicates their likely palaeoenvironmental significance. Selaginella-like herbs and subarborescent lycopods which were low in abundance compared with arborescent lycopods in the early Pennsylvanian appeared to have become prevalent from the Late Pennsylvanian in northern China. However, some arborescent lycopods (mainly sigillarians) still played an important role in the Permian coal forming plants of the region. Several Carboniferous megaspores characteristic of Euramerica persist into the Mid Permian in North China, indicating that a warm and humid climate prevailed in this area during Pennsylvanian to Roadian, whereas the climate of Euramerica had already become arid by the end of the Carboniferous. This warm and humid climate in northern China made it a refuge for some typically Euramerican Carboniferous plants. From Roadian, with the disappearance of coal and marine sediments together with the appearance of red beds, the MS megaspore zone progressively changed to the G zone. This probably reflects the adaptation of the parent plants to a more and more arid climate.

Petrography and palynology of the Blue Gem coal bed (Middle Pennsylvanian), southeastern Kentucky, USA

Petrographic and palynological trends in the Blue Gem coal bed (Middle Pennsylvanian Westphalian B, Breathitt Formation), a thin, low-sulfur, low-ash coal in southeastern Kentucky, were studied in order to establish a depositional model for the seam. Within the study area, the coal bed averages 67 cm and has two distinct zones. The lower and middle parts of the seam (the lower 45–55 cm) are enriched in well-preserved vitrinite and are dominated by arborescent lycopods, sphenopsids, and tree ferns. Fusinite-rich layers, dominated by arborescent lycopods, but also containing herbaceous lycopods and sphenopsids, occur within the lower and middle parts of the seam. The upper part of the seam (the upper 15–25 cm) is recognizable in the field and is distinct in that it contains a greater amount of degraded macerals, and is characterized by high palynomorph diversity, primarily by miospores that are associated with sphenopsids, herbaceous lycopods and arborescent lycopods. These data, in conjunction with geochemical data available for the seam, suggest that initially the peat swamp was fairly diverse and well-nourished (the base of the seam being characterized by a relatively diverse miospore assemblage and a slightly higher ash content). Following this initial planar stage, the Blue Gem peat swamp was probably planar to slightly domed during accumulation of most of the lower and middle parts of the seam, as suggested by the very low ash and sulfur contents, the high telovitrinite content, and the preponderance of arborescent lycopod spores. In its final stages, the peat swamp was domed and is characterized by a more diverse flora and greater levels of degradation of the peat constituents. Sulfur content of this seam is generally low (<1%) but can increase locally to 3–4%. Factors influencing sulfur content include the thickness and nature of the overburden (shale versus sandstone) and petrographic composition.

Depositional history of the Fire Clay coal bed (Late Duckmantian), Eastern Kentucky, USA

More than 3800 coal thickness measurements, proximate analyses from 97 localities, and stratigraphic and sedimentological analyses from more than 300 outcrops and cores were used in conjunction with previously reported palynological and petrographic studies to map individual benches of the coal and document bench-scale variability in the Fire Clay (Hazard No. 4) coal bed across a 1860 km 2 area of the Eastern Kentucky Coal Field. The bench architecture of the Fire Clay coal bed consists of uncommon leader benches, a persistent but variable lower bench, a widespread, and generally thick upper bench, and local, variable rider benches. Rheotrophic conditions are inferred for the leader benches and lower bench based on sedimentological associations, mixed palynomorph assemblages, locally common cannel coal layers, and generally high ash yields. The lower bench consistently exhibits vertical variability in petrography and palynology that reflects changing trophic conditions as topographic depressions infilled. Infilling also led to unconfined flooding and ultimately the drowning of the lower bench mire. The drowned mire was covered by an air-fall volcanic-ash deposit, which produced the characteristic flint clay parting. The extent and uniform thickness of the parting suggests that the ash layer was deposited in water on a relatively flat surface without a thick canopy or extensive standing vegetation across most of the study area. Ash deposits led to regional ponding and establishment of a second planar mire. Because the topography had become a broadly uniform, nutrient-rich surface, upper-bench peats became widespread with large areas of the mire distant to clastic sources. Vertical sections of thick (>70 cm), low-ash yield, upper coal bench show a common palynomorph change from arborescent lycopod dominance upward to fern and densospore-producing, small lycopod dominance, inferred as a shift from planar to ombrotrophic mire phases. Domed mires appear to have been surrounded by wide areas of planar mires, where the coal was thinner (<70 cm), higher in ash yield, and dominated by arborescent lycopods. Rectangular thickness trends suggest that syndepositional faulting influenced peat accumulation, and possibly the position of the domed mire phase. Faulting also influenced post-depositional clastic environments of deposition, resulting in sandstone channels with angular changes in orientation. Channnels and lateral facies were locally draped by high-ash-yield rider coal benches, which sometimes merged with the upper coal bench. These arborescent-lycopod dominant rider coal benches were profoundly controlled by paleotopography, much like the leader coal benches. Each of the benches of coal documented here represent distinctly different mires that came together to form the Fire Clay coal bed, rather than a single mire periodically split by clastic influx. This is significant as each bench of the coal has its own characteristics, which contribute to the total coal characteristics. The large data set allows interpretation of both vertical and lateral limits to postulated domed phases in the upper coal bench, and to the delineation of subtle tectonic structures that allow for meaningful thickness projections beyond the limits of present mining.

Coal-ball floras of Maritime Canada and palynology of the Foord seam: geologic, paleobotanical and paleoecological implications

Coal balls in the Canadian Carboniferous System are known from the Clifton Formation (late Bolsovian) of New Brunswick and from the Foord seam (Stellarton Formation, late Bolsovian) of the Stellarton Basin of Nova Scotia. Coal balls from these two units are dominated by arborescent lycopods but ferns, seed ferns, calamiteans, and cordaiteans also occur. Baxter's list (Baxter, 1960) of coal-ball plants from New Brunswick is updated and these fossil plants are illustrated here for the first time on the basis of an examination of his peels. The palynomorphs and coal-ball plants of the Foord seam of the Stellarton Basin are illustrated and their paleoecology is discussed. Five genera of arborescent lycopods were present in the Foord swamp: Diaphorodendron, Paralycopodites, Lepidophloios, Sigillaria and Lepidodendron. The first three genera are represented in coal balls; the second two are also represented as compressions in the Foord seam; and all genera are represented in the spore assemblages from the Foord seam. The palynostratigraphy indicates that Sigillaria and Diaphorodendron were almost exclusively confined to the upper bench, whereas the other three genera were probably present in the Foord mire throughout its entire history. Palynomorphic changes in the Foord mire probably reflect gradual changes in wet and dry conditions.

Late paleozoic phytogeographic provinces in China and its adjacent regions

China's tectonic history is complex. The country consists of a number of amalgamated plates, microcontinents, and terranes, and consequently contains a wide diversity of floras representing all of the major biogeographic provinces of the late Paleozoic-the Angaran, Cathaysian, Gondwanan, and Euramerican. The boundaries of the late Paleozoic phytogeographic provinces are mostly coincident with the fold belts and deep fault zones that mark the sutures between the four major tectonic blocks within the country. These areas are known as the Junggar-Hinggan Region (a part of the Angaran Realm), the Sino-Korean-Tarim (North China) Block (in the North China Cathaysian Subrealm), the South China Block (in the South China Cathaysian Subrealm), and the Southern Xizang (Tibet)-Western Yunnan Region (in the Gondwanan Realm). The occurrence of Chacassopteris in northern Xinjiang and Angaridium in the eastern part of the Junggar-Hinggan region suggests that the floras in the Junggar-Hinggan region were on the southern fringe of the Angaran Floral Province on the Siberian plate and that the Angaran floras began to differentiate from their Late Devonian ancestors earlier (by the Visean) than the surrounding Euramerican and Cathaysian floras. Intermixing of Angaran and Cathaysian floras beginning in the early Late Permian is interpreted as evidence that collision between the Siberian and the Sino-Korean-Tarim Blocks began at this time and that the floras began to spread north and south across the suture. Climates are interpreted to range between temperate and subtropical. The Cathaysian Floral province consists of two major tectonic blocks (the Sino-Korean-Tarim (North China) Block and the South China Block) and several floral subzones. The lack of provincial differentiation between the Visean floras on the two blocks suggests that collision between them occurred during the Devonian. North and South China were vegetated by Euramerican floras until the Late Carboniferous when Cathaysian elements first began to differentiate in response to differences in the paleogeographic position of the blocks and possibly to tectonic factors. Differentiation did not proceed uniformly across all of the Cathaysian landmass. Rather it began as early as the early Westphalian in some subregions and as late as the Stephanian in others. The two major Cathaysian provinces were established by the Permian. The Cathaysian flora is interpreted to have developed in a tropical, probably ever-wet climatic zone. Tropical conditions persisted in South China throughout the Permian, but in North China, by early Late Permian, climatic conditions alternated between wet and dry, and by late Late Permian most of the Northern Hemisphere was experiencing extreme arid conditions. Large leaved forms like Taeniopteris are more common in North China compared to South China and the genus Gigantopteris is almost completely restricted to South China. South China also contains an abundance of Psaronius tree ferns and Gleicheniaceous ferns. Though arborescent lycopods were in a general state of decline, some species like Lepidodendron oculus-felis were still widespread in the Late Permian of South China. In the southern Xizang (Tibet)-western Yunnan Regions, floras from the Devonian to the Early Carboniferous, though somewhat endemic in nature, closely resembled the Eurasian floras. After the Early Carboniferous, two floral sub-provinces developed in Tibet. The sub-province south of the Yarlung-Zangbu Suture characteristically contains sediments with diamictites, a cold-water Stephanoviella fuana during the Late Carboniferous and a Gondwana flora during the Early Permian. This region is accepted to be part of the Indian Plate and is unquestionably part of the Gondwana Floral Province. The sub-province between the Yarlung-Zangbu Suture and the Bangongco-Dengqen Suture (known also as the Gangdis-Nyainqentanglha tectonic region) also contains diamictites and a Stephanoviella fauna, but contains none of the elements typical of the Glossopteris flora. This subprovince occasionally contains a few faunal elements typical of South China. The tectonic characteristics and the distribution of marine invertebrates and diamictite deposits suggest that the Chinese Gondwana province was a coherent landmass, the Median Plate, located on the northern fringe of Gondwanaland.

A palynofacies analysis of the Dinantian (Asbian) Glenade Sandstone Formation of the Leitrim Group, northwest Ireland

Abstract A quantitative palynofacies analysis of the Dinantian (Asbian) Glenade Sandstone Formation in two boreholes from the Glangevlin area, northwest Ireland, was carried out. It was found that the sands of the Glenade Sandstone Formation prograded rapidly over an arid lagoonal environment in the area of the more proximal northern borehole, but were deposited directly on top of the laminated dolomites of the underlying Meenymore Formation in the area of the southern borehole. Fluvial conditions predominated in the northern area, while lagoonal conditions were established in the southern area, before a major anoxic marine transgression, 12.7 m above the base of the Glenade Sandstone Formation in both areas, submerged the flat landscape. In both areas the dominantly fluvial environment above the marine transgression was periodically replaced by more lagoonal environments. The flora at the time of deposition of the Glenade Sandstone Formation may have been dominated by ferns, tree-ferns and small seed-ferns, while herbaceous and arborescent lycopods, typically present in Carboniferous coal swamps, may have been absent.

Discovery of permineralized plant fossils (coal balls) in the Bolsovian (e.g., Westphalian C) (Middle Pennsylvanian, Upper Carboniferous), Stellarton Basin, Nova Scotia, Canada

Permineralized plant fossils (coal balls) of Bolsovian age (ex Westphalian C) were discovered in the Foord seam of the Stellarton Basin of Nova Scotia. The coal-ball plants were preserved in a siderite–dolomite matrix and formed in a nonmarine intermontane setting. The coal-ball flora is dominated by arborescent lycopods and contains a few ferns, as well as occasional seed ferns, calamiteans, and cordaiteans. The following taxa were identified: Diaphorodendron, Paralycopodites brevifolia, Lepidocarpon lomaxii, Stigmaria, Scolecopteris, Botryopteris tridentata, Medullosa, Heterangium, Astromyelon, and Cordaianthus. This assemblage contains plants typical of Westphalian coal-swamp floras and helps fill a stratigraphie gap in Westphalian coal-ball floras of Euramerica. Key words: permineralized plants, coal balls, Carboniferous, Canada.

Lyginopterid seed ferns in basal Upper Carboniferous marine black shale deposits of midcontinent North America

Permineralized plant remains occur individually and in small mats within anoxic and dysoxic marine black shales deposited seaward of the Wedington delta (Fayetteville Formation, Middle Chester) in northwestern Arkansas. Plant debris and associated cephalopods occur within 20 km of offshore bars that developed at the mouths of delta distributary channels. The bars were produced by longshore paleocurrents flowing eastward among the southwestern margin of the Ozark Dome. The flora includes several genera of arborescent lycopods, zygopteridalean ferns, filicalean ferns, calamites, medullosan seed ferns and seed fern remains with features that are characteristic of the Lyginopteridaceae. Among the lyginopteridalean stems are specimens that have been described as Megaloxylon wheelerae, an arborescent form, as well as several undescribed species.Two stems with prominent leaf scars represent one species of a new genus. The stems measure 35 cm and 34 cm long, and are approximately 2.5 cm in diameter. Leaf arrangement is helical, approaching a 3/8 phyllotaxis, with internodal lengths of about 3 cm. Stems are eustelic with a polygonal primary body 3-4 mm in diameter. Each leaf trace diverges from the cauline bundle as a single strand. The strand trifurcates in the cortex to produce a distinctive configuration of two c-shaped lateral bundles separated by a tangentially elongated central strand.Pith cells are large with prominent walls. Some show internal contents suggestive of secretory substances. The primary body is surrounded by a distinctive zone of wood 3-4 cm wide. Large rays 2-5 cells wide and more than 8 mm high separate wedges of tracheids that typically are 2-4 cells wide. Secondary tracheids display multiseriate oval bordered pits on the radial walls. Vascular cambium and secondary phloem are present, but incompletely preserved. The cortex is differentiated into an inner parenchymatous zone with horizontally elongated “sclerotic” nests, and an outer zone of alternating bands of vertically elongated sclerenchyma and parenchyma.This material significantly increases our knowledge of Namurian floras inhabiting non peat-forming environments, and emphasizes the systematic diversity among hydrasperman gymnosperms at the base of the Upper Carboniferous.

Reconciling the lithologic and paleobotanic records of climatic change during the Pennsylvanian

Both lithologic and paleobotanic data have been used to construct climatic curves for the Pennsylvanian of the Appalachian Basin (Figure 1). The strengths and weaknesses of each type of evidence must be considered when reconciling these data into a composite curve. (1) The calibrated lithologic curve is based ultimately on the geographic ranges of sediments and soils relative to modern precipitation. Although it provides quantitative estimates of precipitation, the calibrated curve cannot detect minor fluctuations in climate, and time-averaging of range data can lead to an over-estimate of the rate of climatic change. (2) The geochemical model, although uncalibrated, uses essentially the same data as the calibrated curve. It avoids some of the problems of time-averaging by incorporating rough estimates of abundance. Although the long-term curve portrays a uniform climate during the earlier Pennsylvanian, lithologic data may be insensitive to climatic fluctuations in extremely wet climates. (3) The abundance of arborescent lycopods in coal may be a useful climatic indicator through much of the Pennsylvanian, but its usefulness in the Mississippian (before the evolution of non-lycopod swamp trees) and the latest Pennsylvanian (after a major extinction of arborescent lycopods) must be questioned. (4) The abundance of coal resources (as with any other climatic indicator) depends on many factors other than climate. The lack of congruence between the coal abundance curve and the other curves emphasizes the importance of including non-climatic factors in any model that predicts coal resources based on paleoclimate.The composite curve takes its overall shape from the geochemical model, quantifies it using the calibrated curve, and details climatic trends in the wet lower Pennsylvanian based on lycopod abundance data. The major weakness of the composite curve is that it ignores potential variations in seasonality of precipitation.

Palynologic and petrographic variation in the Pond Creek coal bed, Pike County, Kentucky

Recent studies of the petrology and ash geochemistry of the Pond Creek coal bed (Middle Pennsylvanian Breathitt Formation) in Pike and Martin Countries, Kentucky, have defined vertical and lateral trends that are related to the development of the northeast-trending Belfry anticline contemporaneous with the deposition of the Pond Creek peat. To the northwest of the anticline the coal bed has a high-CaCO 3 middle zone and a high Fe 2O 3-high sulfur upper zone. To the east of the anticline, particularly in the Lick Creek and Jamboree 7 1 2 ′ quadrangles, the coal bed exhibits a distinctive petrographic zonation. In the latter area, the usual megascopic sequence is a basal durain followed by a bright clarain-durain/dull The palynology of the Pond Creek coal bed was investigated in six sets of bench/lithotype samples from the Lick Creek and Jamboree 7 1 2 ′ quadrangles. The low-vitrinite basal durain (zone 1) has a palynomorph assemblage which reflects the importance of tree ferns and herbaceous lycopods. The easternmost site has a bright clarain below the durain. The latter lithotype has a fair diversity of palynormph groups and also has the highest percentage of arborescent lycopod forms of any bench below the bone (zone 5). The bright zone 2 above the durain has the greatest maceral group range and the greatest floral diversity of any of the lithotypes. The zone 3 dull lithotype has increased amounts of herbaceous lycopods and decreased amounts of arborescent lycopods, sphenopsids and tree ferns. The zone 4 bright lithotypes are generally over 80% vitrinite and, in general, exhibit a dominance of arborescent lycopods although sphenopsid, tree fern and small fern forms exhibit varying importance. The high-ash bone (zone 5) has 71.6–77.0% vitrinite. This lithotype is marked by a dominance of herbaceous lycopods at the expense of arborescent lycopods and sphenopsids. The zone 6 bright clarian is marked by an increase in arborescent lycopods and a large decrease in herbaceous lycopods. The low-vitrinite terminal durain has an assemblage with high percentages of herbaceous lycopods and low percentages of arborescent lycopods as well as increase in tree fern spores over zone 6. In general, the petrology and palynology trends are predictable. Dull lithotypes have abundant herbaceous lycopod representation and bright lithotypes have abundant arborescent lycopod representation. The greatest deviation from this simple pattern is within the zone 4 bright lithotypes, where diverse palynomorph assemblages occur among the high-vitrinite benches. Overall, the greatest floral diversity appears to have occurred near the base of the coal bed.

Paleoecological interpretation of a middle Pennsylvanian coal bed in the central Appalachian basin, U.S.A.

At least 180 small spore species assignable to 62 miospore genera have been identified from the Middle Pennsylvanian Hernshaw coal bed in southern West Virginia, and its stratigraphic equivalent, the Fire Clay coal bed, in eastern Kentucky. The established natural affinities of a majority of these miospore taxa indicate that the Hernshaw-Fire Clay peat swamp supported a diverse flora consisting of arborescent and “herbaceous” lycopods, ferns (tree-like and small varities), calamities and cordaites. Four floral groupings are recognized in the Hernshaw-Fire Clay coal bed. The inferred paleoecology and vertical stratification of each of these four floral groupings is similar in structure to the “phasic” floral communities found in modern domed peat systems, suggesting that the ancient Hernshaw-Fire Clay peat swamp was a domed deposit. Compositional characteristics (petrographic make up, ash yield and sulfur content) associated with the four groupings are consistent with, and support this interpretation. Where uninterrupted by inorganic partings, the Hernshaw-Fire Clay coal bed commonly contains basal coal layers dominated by Lycospora-bearing arborescent lycopods, with successive increments showing a progression to a more fern- and “herbaceous”-lycopod-dominant flora in younger layers. These observations are corroborated by petrographic analyses, which show the bed to be compositionally stratified. Increments dominated by Lycospora have high vitrinite contents, in contrast to increments containing increased percentages of fern- and “herbaceous”-lycopod-affiliated taxa that are enriched in inertinite macerals. The volcanic ash fall, preserved as the flint-clay parting in the Hernshaw-Fire Clay coal bed, had a considerable effect on the development of the ancient Hernshaw-Fire Clay peat swamp. Besides interrupting peat formation, the presence of an inorganic substrate represent a major change in edaphic conditions within the swamp. This disruption is demonstrated by a change in palynflora and by the establishment and proliferation of some plant groups, notably cordaites and calamites, that may have been better adapted to growth on mineral soils. These palynologic and petrographic relationships, thought to be indicative of a domed peat-swamp origin, are not confined to the Hernshaw-Fire Clay coal bed, but appear to be characteristic of many coal beds in the Appalachian basin, and also of coal beds in other basins.

Phytogeographic patterns and continental configurations during the Permian Period

Abstract The climatic influences on vegetation in the present world can serve as an excellent model for the Permian, there being approximately the same level of floral differentiation and the same relatively cold polar regions. Accordingly, a system of present day climatically defined biomes, developed by Walter, is adapted herein for palaeophytogeographic purposes. There are ten biomes altogether which range from the tropical 'everwet' (biome 1) to the polar 'glacial' (biome 10). Biome 1 is represented by the tropical rainforests of the Cathaysian province sensu stricto which was populated by the arborescent lycopods and sphenophytes, and the Gigantopterids which are interpreted as lianas (vines). This is flanked by the lower diversity 'summerwet' biome 2, the Atlantic Province, a zone which today is characterized by savanna vegetation, and in the Permian was represented by the pteridosperm Callipteris and the primitive conifers. Biome 3 was effectively 'abiotic' and is expressed geologically by evaporite belts. The 'winterwet' or Mediterranean climate of today (biome 4) was not well developed in the Permian, or perhaps just not well preserved, but I attribute some low diversity floras of Kazakhstan to this biome. Biome 5, the 'warm temperate' biome is well developed in both hemispheres, and, like biome 1, is characterized by high diversity floras and abundant swamp deposits. Not surprisingly, the biome 5 floras have been mistaken for biome 1 with which they are transitional in the modern world and with which they share similar climatic conditions. In the Permian Angaran Realm, the Pechora Province represents this biome, while the Austroafroamerican Province is the Gondwanan equivalent. Often, biome 5 floras have been simply termed 'mixed'. Proceeding poleward across the 'hard frost line', the cool temperate floras of biome 6 were populated by diverse herbaceous sphenophytes and deciduous trees (the cordaitids of Angara and the similarly diverse glossopterids of Gondwana). Areas in the temperate zone that were remote from moisture sources are assigned to biome 7 and are only known in the southern hemisphere by some aeolian deposits in Argentina. The 'cold temperate' biome 8 is a low diversity equivalent of biome 6, and has been given the name Gangamopteris Flora in the southern hemisphere. The 'tundra' environment, biome 9, and the truly glacial deposits, biome 10, are known only from the southern hemisphere.

ONTOGENY AND PALEOECOLOGY OF THE MIDDLE PENNSYLVANIAN ARBORESCENT LYCOPOD BOTHRODENDRON PUNCTATUM, BOTHRODENDRACEAE (WESTERN MIDDLE ANTHRACITE FIELD, SHAMOKIN QUADRANGLE, PENNSYLVANIA)

Study of an in situ Bothrodendron punctatum community in a strip mine in Bear Valley, Shamokin Quadrangle, Pennsylvania, provides new insights into the ontogeny of Middle Pennsylvanian arborescent lycopods and into the ecological and environmental characteristics of lycopod‐dominated clastic‐swamp communities. Bothrodendron punctatum began growth as a monocaulous stem. The first branches developed when the stem attained a minimum height of 5 m. Lateral branches bore terminal cones and were determinate and deciduous. They grew to a maximum length of 1 m, and became smaller and more closely spaced with increasing stem height. The branch scars were not disrupted by secondary stem growth indicating that the branches stayed attached until the stem attained its determinate growth limit. The plant grew to a height of 25 m. Though B. punctatum is an uncommon component of Euramerican floras, the plant could become locally dominant under favorable environmental and edaphic conditions. The upper canopy was formed by B. punctatum and contained emergents of Lepidodendron aculeatum and a Sigillaria species. The understory contained pteridosperms and rare Calamites. Bothrodendron punctatum seems to have preferred environments transitional between clastic and peat swamp conditions. It was sensitive to local inhomogeneity in microhabitat characteristics, as well as to regional climatic fluctuations (drought stress). Both these variables produce specifically attributable effects on branch size and separation trends.

Paleoecology of an upper Middle Pennsylvanian coal swamp from Western Pennsylvania, U.S.A.

The first sufficient quantitative analysis of vegetation preserved in coal balls from the Allegheny Formation, late Middle Pennsylvanian age, was made in the present study by measuring 13,203 cm 2 from middle peels of over 300 coal balls or pieces of coal balls. The distinctive features of this flora are the dominance of lycopods, the absence of cordaitean plants, and the extremely low shoot/root ratio (0.74 for total plant remains, 0.24 for lycopods). It is suggested that the climate at the Derringer Corners coal swamps was a drier tropical climate, compared to that of some earlier coal-forming environment of the Appalachian Basin, and to those of coal swamps in the Illinois Basin during the Middle Pennsylvanian. The discrepancy between the abundance of lycopods (as an indicator of a wet environment or habitat) and the low shoot/root ratio (inferring relatively dry conditions) in the coal-forming peat swamps at the Derringer Corners indicates that the actual set of factors causing massive reduction of arborescent lycopods at, or near, the boundary between Middle and Late Pennsylvanian would be much more complex than simply a “drier climate”. Some local factors, such as edaphic, perhaps geomorphic conditions, and local events, might play an important role in creating a favorable environment for the growth of lycopod trees.

Vegetational history of the Springfield coal (Middle Pennsylvanian of Illinois) and distribution patterns of a tree-fern miospore, Thymospora pseudothiessenii, based on miospore profiles

The vegetational history of the Springfield (No. 5) Coal Member in the southwestern and southeasternmost portion of the Illinois Basin is reconstructed from palynological profiles of the coal seam. In most parts of the swamp dominance was shared by arborescent lycopods that produced Lycospora granulata, and two tree ferns that produced Thymospora pseudothiessenii and Laevigatosporites globosus. The profiles suggest that populations of the Thymospora producing tree fern occupied sites for long periods. In the Southwestern portion of the basin vegetation changes can be correlated to the splitting of a coal in the proximity to a paleochannel. A greater understanding of the ecological requirements of some of the spore taxa of the Springfield Coal is seen by the patterns of the same taxa in surrounding Spoon and Carbondale Coals. Some taxa appear to be more generalists and other more specialists that are more restricted to a certain type of coal.