John Utting

Palynology of Upper Permian and Lower Triassic rocks, Meishan, Changxing County, Zhejiang Province, China

Abstract The marine sequence exposed at Meishan, Changing County, Zhejiang Province, China, is a candidate for the stratotype of the youngest Permian stage in the world, the Changhsingian, and also for the Permian-Triassic boundary. Three microfloral assemblage zones, documented here for the first time, have been recognized. In ascending order they are: (1) Leiosphaeridia changxingensis-Micrhystridium stellatum Assemblage Zone from the Changhing Formation (Changhsingian); (2) Vittatina-Protohaploxypinus Assemblage Zone from the basal part of the Lower Chinglung Formation (earliest Griesbachian); and (3) Lunatisporites-Ephedripites Assemblage Zone from the upper part of the same formation (Griesbachian). The Vittatina-Protohaploxypinus Assemblage Zone occurs in “mixed” fauna beds 1 and 2, and in the lower part of 3, whereas the Lunatisporites-Ephedripites Assemblage Zone occurs in the middle and upper parts of “mixed” fauna bed 3 and slightly above. The age implications, the problems of transitional floras, miospore reworking and paleoenvironments are discussed. Miospores and a few acritarchs, are illustrated; two new species, Lunatisporites orientalis and Leiosphaeridia changxingensis , and two new combinations, Platysaccus insignis and Platysaccus sp. cf. P. canadensis , are described. The thermal maturity of the palynomorphs is low and falls within the ‘oil window’. Sedimentological, paleontological and geochemical elemental analyses suggest that sedimentation may have been continuous across the Permian-Triassic boundary at Meishan, or that any hiatus was small.

Stratigraphy and palynostratigraphy, Karoo Supergroup (Permian and Triassic), mid-Zambezi Valley, southern Zambia

Abstract The Karoo Supergroup outcropst in the mid-Zambezi Valley, southern Zambia. It is underlain by the Sinakumbe Group of Ordovician to Devonian age. The Lower Karoo Group (Late Carboniferous to Permian age) consists of the basal Siankondobo Sandstone Formation, which comprises three facies, overlain by the Gwembe Coal Formation with its economically important coal deposits, in turn overlain by the Madumabisa Mudstone Formation which consists of lacustrine mudstone, calcilutite, sandstone, and concretionary calcareous beds. The Upper Karoo Group (Triassic to Early Jurassic) is sub-divided into the coarsely arenaceous Escarpment Grit, overlain by the fining upwards Interbedded Sandstone and Mudstone, Red Sandstone; and Batoka Basalt Formations. Palynomorph assemblages suggest that the Siankondobo Sandstone Formation is Late Carboniferous (Gzhelian) to Early Permian (Asselian to Early Sakmarian) in age, the Gwembe Coal Formation Early Permian (Artinskian to Kungurian), the Madumabisa Mudstone Late Permian (Tatarian), and the Interbedded Sandstone and Mudstone Early or Middle Triassic (Late Scythian or Anisian). The marked quantitative variations in the assemblages are due partly to age differences, but they also reflect vegetational differences resulting from different paleoclimates and different facies. The low thermal maturity of the formations (Thermal Alteration Index 2) suggests that the rocks are oil prone. However, the general scarcity of amorphous kerogen, such as the alga Botryococcus sp., and the low proportion of exinous material, indicates a low potential for liquid hydrocarbons. Gas may have been generated, particularly in the coal seams of the Gwembe Coal Formation, that are more deeply buried.

Lower Karroo pollen and spore assemblages from the coal measures and underlying sediments of the Siankondobo coalfield, Mid‐Zambezi valley, Zambia

Abstract A palynological investigation of three boreholes in the Lower Karroo of the Kazinze area of the Siankondobo coalfield (GS 31, 35 and 36), has indicated pollen and spore assemblages in the coal measures and underlying arenaceous beds. The arenaceous sediments occuring at the bottom of the Karroo succession, are part of the Siankondobo Sandstone Formation. They are relatively unfossiliferous, although rare thin mudstone intercalations found in one of the boreholes (GS 36), contain assemblages dominated by monosaccate forms (Cannanoropollis obscurus and Plicatipollenites indicus). The Gwernbe Coal Formation, (Ecca series), which rests unconformably on the Siankondobo Sandstone Formation contains at its base a dominantly arenaceous member (Maamba Sandstone), and in one of the boreholes (GS 31) carbonaceous shale intercalations contain mainly trilete spores e.g. Punctatisporites gretensis, Acanthotriletes filiformis and Apiculatisporis levis. Overlying the Maamba Sandstone is a coal seam (Main Seam), ...

Palynostratigraphy of Mississippian and Pennsylvanian rocks, Joggins area, Nova Scotia and New Brunswick, Canada

Carboniferous rocks in the Joggins area, Nova Scotia, and the Maringouin Peninsula, New Brunswick, are world renowned for their well-preserved macroflora, but this paper is the first detailed study of the palynoflora. The section is comprised of the Mississippian Windsor and Mabou groups overlain disconformably by the Lower Pennsylvanian Cumberland Group. The Windsor Group rocks proved to be barren of palynomorphs but the Mabou Group yielded spores and pollen of Brigantian (late Viséan) to Arnsbergian age (early Namurian = early Serpukhovian). The assemblages are assigned successively to the Schopfipollenites acadiensis—Knoxisporites triradiatus, the Grandispora spinosa—Ibrahimispores magnificus, and the Reticulatisporites carnosus Zones. A major palynofloral change takes place between the Mississippian Mabou and the Pennsylvanian Cumberland assemblages. This is believed to reflect a significant regional hiatus in the Joggins section and elsewhere in eastern Canada. The Cumberland Group is characterized by an abundance of Lycospora spp. and monosaccate gymnosperm species of Yeadonian? (Late Namurian = middle Bashkirian?) to late Duckmantian (late Bashkirian?) age. The palynological succession is divided into the Raistrickia saetosa, the Raistrickia fulva, and the Vestispora magna zones. Age determinations of the zones, based on comparisons with Western Europe and the North Sea, are tentative because the Cumberland assemblages lack diversity and many taxa diagnostic in Western Europe are absent in the assemblages of the Joggins area, possibly due to environmental and climatic differences. Geological Survey of Canada Contribution Number: 20090031

The geology, petrology, palynology and geochemistry of Permian coal basins in Tanzania. 1. Namwele-Mkomolo, Muze and Galula coalfields

Abstract Permian coal-bearing strata occur in a number of intracratonic rift basins in Tanzania. This study examines coals, shales and mudstones of the Namwele-Mkomolo, Muze and Galula coalfields (Rukwa basin) by coal petrological, palynological and rock eval techniques. For the coals the focus was on the establishment of coal seam characteristics and related quality and utilization potentials, whereas the shales and mudstones were examined for age relationships, flora and related palaeodepositional environments and source rock potential. The coal seams, which have a thickness of up to 2.95 m are high in ash yields (25–63 wt%) and have calorific values ranging from 5344 to 18947 J/g. Typical for many of the seams is their detrital nature as indicated by the high content in finely disseminated clay minerals, quartz and detrital macerals. Pyrite content is variable (0.60–5.81 wt%). Vitrinite reflectance ranges from 0.43 to 0.66% Rrandom (subbituminous to high volatile B bituminous). Use of the coals in small-scale power generations and for domestic use would greatly reduce the dependency of rural Tanzania on wood and wood-derived charcoal as the main source of fuel. Palynomorph assemblages are characterized by the predominance of nontaeniate and taeniate pollen, and trilete spores in the Namwele-Mkomolo and Muze coalfields. At Galula coalfield the palynomorph assemblages were poor (rare trilete, alete and monolete spores). On the basis of age correlations with Karoo basins to the south and the Collie Basin of western Australia, an Artinskian to Kungurian(?) age is suggested for the coal measures in the Rukwa basin. The diversity of palynomorph assemblages suggests a variety of floras and contemporary depositional environments throughout deposition of the Karoo strata. This is consistent with coal petrographic parameter, which would indicate that peat accumulation occurred in upper delta plain, braided plain and lacustrine depositional environments. Rock eval parameters indicate kerogen type III for all samples investigated and indicate very poor hydrocarbon source rock potential.

REWORKED MIOSPORES IN THE UPPER PALEOZOIC AND LOWER TRIASSIC OF THE NORTHERN CIRCUM-POLAR AREA AND SELECTED LOCALITIES

Abstract Reworking of Devonian, Carboniferous and Permian palynomorphs into the Lower Triassic of western Canada, Yukon, the Canadian Arctic Archipelago and Alaska has been documented by a number of workers. The phenomenon occurs in other northern circumpolar localities, such as East Greenland and the Barents Sea, and was probably widespread. Examples are given from western and eastern Europe, Russia, the Middle East, Pakistan, China, Brazil and Australia. The abundance and diversity of reworked palynomorphs from a number of stratigraphic units of different ages into the Lower Triassic is an important palynostratigraphic phenomenon of chronostratigraphic value. It may be the result of a major regional regression in the late Permian, followed by a widespread marine transgression in the Early Triassic, or it may be due to tectonic activity resulting in eustatic sea-level rise. Whatever the mechanism, the advancing transgression resulted in erosion of exposed Devonian, Carboniferous and Permian rocks, but by Mid-Triassic times most pre-Triassic rocks had been covered by sediment, and the supply of reworked material much reduced. Reworked Devonian taxa belong to a variety of suprageneric groups including cavate trilete spores (lycopsids), acavate trilete spores (ferns) and monolete spores; Lower Carboniferous taxa include cingulate trilete spores. Possibly reworked Upper Carboniferous and Permian pollen includes that of Gymnosperms—Cordaites, conifers, pteridosperms (taeniate bisaccate and polyplicates), and cycads and gnetophytes. Lower Triassic palynomorphs, possibly in situ, may include (sometimes abundant) acanthomorph acritarchs such as Micrhystridium breve, M. setasessitante, M. fragile and Wilsonastrum colonicum. Lack of recognition of reworking has many implications concerning chronostratigraphy, palynostratigraphy, paleoenvironments, paleoclimates, coal petrography, thermal maturity, geochemistry, and chemostratigraphy. For example, if the Upper Permian and Lower Triassic Densoisporites playfordii, D. complicatus, D. nejburgii, Lundbladispora obsoleta and Aculeisporites variabilis are not in situ, but reworked specimens of the Devonian progymnosperm cavate morphon Geminospora lemurata, one has to question the commonly held view that a lycopsid dominated macroflora, with a large biomass, re-colonised the land in the Early Triassic. Lower Triassic assemblages in which reworking occurred but has not been recognised may give the impression of palynofloral diversity, whereas low diversity and low abundance would be more consistent with the hostile arid environment of the Lower Triassic. One Upper Permian and Lower Triassic plant entity, well-adapted to harsh conditions, was the algal cyst Chordecystia chalasta. Nevertheless, some higher plants must have survived the Permian–Triassic crisis as witnessed by the presence of gymnosperm pollen in the Mesozoic. This is Geological Survey of Canada (Calgary), Contribution no. 2004237.

Petrographical, palynological and geochemical analyses of the Hub and Harbour seams, Sydney Coalfield, Nova Scotia, Canada—implications for facies development

Abstract Benched channel samples and continuous block samples of the Hub and Harbour seams from the Sydney Basin, Nova Scotia were studied to define the variations in petrography, geochemistry and palynology of the seams and to interpret the depositional environments of the precursor mires. Petrographic compositions of the seams are very similar with high vitrinite content, low inertinite, moderate liptinite and negligible clastic mineral content. Pyrite content is moderate. There is little variation in petrographic composition between benches in either seam. There are marked variations in petrographic compositions at the lithotype scale. Petrographic facies parameters indicate deposition of the bulk of both seams under fairly uniform conditions in relatively wet mires. Unusually wet or dry periods were rare. The palynological assemblages of both seams indicate a middle to late Westphalian D age. The common to abundant palynomorphs are derived from “arborescent” and “herbaceous” lycopsids, tree ferns and other ferns(?), and sphenopsids. The palynological assemblages support the petrographic interpretation of relatively wet mires. Cordaites pollen (Florinites) is rare, suggesting that there was little contribution from plants growing in dry or upland areas. The absence of the Densospore miospore phase, and the petrographic data, indicate there were no periods in which domed mires occurred. The distinctive dull bands occurring in the Hub and Harbour seams are characterised by low vitrinite contents, high inertinite content, high liptinite and common detrital minerals. Sporinite, showing varying degrees of degradation, is commonly highly concentrated in thin bands. The geochemistry is marked by much higher hi values than normally reported for coals but other indices are typical for coals of this rank. The palynological assemblages of the dull bands are dominated by tree fern spores and other ferns(?) with only a minor contribution by sphenopsid spores. The dull bands were deposited during periods of inundation of mires. Relatively low mineral content indicates that the distributary channels which flooded the mires were quite distant from the depositional sites of the samples.

The geology, petrology, palynology and geochemistry of Permian coal basins in Tanzania: 2. Songwe-Kiwira Coalfield

Abstract This study provides coal quality, petrological, palynological and geochemical (Rock Eval) data on Permian coal seams and associated shales and mudstones of the Karoo Supergroup of the Songwe-Kiwira Coalfield, Tanzania. The coal seams, which have a cumulative thickness of 6.80 m, occur in the shale–coal–sandstone facies of the Mchuchuma Formation of Artinskian to Kungurian(?) age. Coal quality data (calorific values, volatile matter contents) and vitrinite reflectances indicate high volatile C bituminous to high volatile A bituminous coals, having relatively high ash yields (22–49 wt.%) and highly variable sulphur contents (0.17–9.2 wt.%). They could be used to fuel small-scale power generation units thereby providing electricity to nearby towns and villages. Also, the coals could be used as a substitute for wood, which is becoming increasingly scarce. In rural Tanzania, charcoal is still the main energy source for cooking, and wood is used extensively in brick kilns and for making roofing tiles. Petrological analysis indicated that the coals are dominated by dull to banded dull lithotypes, with seams at the base of the Mchuchuma Formation enriched in inertinite macerals (up to 83 vol.%), whereas up-section vitrinite contents increase. Palynological analyses indicated that the assemblage in the lower Mchuchuma Formation ( Scheuringipollenites assemblage) is dominated by trilete spores, whereas in the remainder of the section, non-taeniate disaccates dominate ( Scheuringipollenites–Protohaploxypinus assemblage). Facies critical macerals suggest for most seams a marsh/wet forest swamp depositional setting, which is consistent with the palynological data. Rock Eval analyses indicate type II/III kerogen, with Tmax (°C) values ranging from 426 to 440, corresponding to the early stage of hydrocarbon generation. Thermal Alteration Indices (2 to 2+) and vitrinite reflectance levels (0.60–0.83 Ro (%) support the Rock Eval maturity assessment, and despite the predominance of terrestrial-derived organic matter, there is evidence of oil generation and expulsion in the form of cavity and fracture filling exsudatinite.

Late Early Permian plant fossils from the Canadian High Arctic: a rare paleoenvironmental/climatic window in northwest Pangea

Abstract Recently discovered megafossil plant remains in late Early Permian (Kungurian) marine sediments on northern Axel Heiberg Island, Canadian Arctic Archipelago, provide a much needed datum point for paleobiogeographic considerations in this part of North America. The fossil plants represent at least ten families belonging to several major groups (sphenopsids, ferns, pteridosperms, ginkgos, cordaitaleans, and conifers). The conifers Rufloria and Walchia are the most commonly represented taxa, while other gymnosperms constitute much of the remaining collection. Lycopsids are absent and sphenopsids as well as ferns are present, but rare. The plant material probably originated from Crockerland and has a complex taphonomic history. There appears to be a strong phytogeographic connection with the Angaran floral realm. In addition, some floral elements occurring here are known mostly from the Early Mesozoic elsewhere. These findings support the idea that plant evolution was most intensive in extrabasinal settings; with migration into the depositional lowlands often occurring at times when climatic conditions became favorable for range expansion out of the uplands. The Axel Heiberg Island flora is another datum point for rare, but significant late Early Permian age floras on the North American continent.

Kennetcook thrust system: late Paleozoic transpression near the southern margin of the Maritimes Basin, Nova Scotia

A major zone of deformation affects Early Carboniferous rocks in the southern part of the Maritimes Basin of Nova Scotia, close to the boundary between the Avalon and Meguma terranes of the Appalachians. Field relationships at Cheverie indicate thrusting of Tournaisian Horton Group clastics over Visean Windsor Group carbonates, evaporites, and clastics, a relationship confirmed by the Cheverie #01 well. Mapped relationships to the south indicate that a system of thrusts, here termed the Kennetcook thrust system, climbs upsection to the southeast, becoming a decollement within Windsor Group evaporites. Industry seismic profiles clearly show deformed Windsor Group, and include fold and fault structures indicative of evaporite flow and solution collapse. Below the Windsor Group, half-grabens filled with Horton Group are clearly imaged; offsets at graben-related faults show that these structures were inverted during later shortening. Above the Windsor Group, less deformed rocks of the Pennsylvanian Scotch Vil...