Miospore Assemblages Research Articles

Petrographic, palynological and geochemical recognition of dispersed organic matter in the black Anthracosia Shales (Sudetes, south-west Poland)

We describe the organic petrography, palynology and Rock-Eval pyrolysis values of lacustrine black shales termed the Anthracosia Shales (Upper Carboniferous/Lower Permian) in the Intrasudetic Basin (Sudetes, SW Poland). Samples were taken from cores of two boreholes: Rybnica Leśna PIG 1 and Ścinawka Średnia PIG 1. Maceral composition, miospore assemblage composition, palynofacies and geochemical characteristics of dispersed organic matter in the Anthracosia Shales were used to determine conditions of the environment and to evaluate their petroleum potential. Data from both organic petrography and palynology analyses enabled recognition of three broadly distinct organic associations in these shales: bituminous, humic, and intermediate, while Rock-Eval pyrolysis revealed the presence of bituminous and humic kerogen types I and III. Type I corresponds to the bituminous association, with amorphous organic matter (AOM) dominant in the palynofacies, and type III corresponds to the humic association with phytoclasts prevailing in the palynofacies. The thermal maturity of the organic matter is determined by the values of: (1) vitrinite reflectance V Ro = 0.53–0.73%, (2) palynomorph 3–4 colour index, and (3) T max = 443–447°C, which indicate oil window maturity. Some of the TOC results (1.6–2.9 wt.%) indicate that the Anthracosia Shales are good and very good petroleum source rocks, though the thickness of this interval is low (4–5 m). Shales with TOC values <0.5 wt.% prevail, and may be classifed as poor source rocks.

A diverse Early Devonian palynoflora from the Waxweiler Lagerstätte (Klerf Formation, Rhenish Massif, Western Germany): palaeobotanical implications

The Lower Devonian Klerf Formation is an exceptional Konservat-Lagerstätte, exposed at multiple sites in the Waxweiler region in the Eifel area, western Germany. It has been studied for its various fossils, mainly arthropods, fishes, plants, molluscs, brachiopods and crinoids. At Waxweiler, the strata are palaeoecologically interpreted as a prograding deltaic depositional system elongate from NW to SE in the Ardenno-Rhenish area. The Klerf Formation has, however, not been studied in full in terms of its microflora and microfauna. Our study of the formation from two different quarries in the Waxweiler area yielded fairly diverse miospore assemblages dominated by abundant organic matter in varying degrees of coalification. The miospore assemblages are mainly composed of classic Lower Devonian taxa of the Old Red Continent (Laurussia). These belong, among others, to the genera Ambitisporites, Apiculiretusispora and Retusotriletes. Biostratigraphically more important species recovered include Acinosporites lindlarensis, Apiculiretusispora brandtii, Cymbosporites asymetricus, Diatomozonotriletes franklinii, Emphanisporites annulatus, Verruciretusispora dubia and Verrucosisporites polygonalis. In addition, Emphanisporites foveolatus, which is known only from a limited area in the Ardenno-Rhenish region, is also identified, indicating an earliest Pragian to middle Emsian age for the composite section. These assemblages are found to be accompanied by reworked phytoplankton to a much lesser extent. Our results reveal a much larger palaeobotanical diversity from the Rhineland outcrops than previously known, indicating a well-developed Psilophyton-type vegetation with related plants. The results further suggest a likely presence of plants such as Leclercqia and Pertica.

Early Devonian organic-walled phytoplankton from the Ponta Grossa Formation, Paraná Basin, Brazil

The depositional succession of the Ponta Grossa Formation (Paraná Basin) corresponds to a wave-dominated shallow-marine environment, represented by four coarsening-upwards cycles, limited by flooding surfaces. Previous studies on a well-preserved and diverse assemblage of miospores indicated a late Pragian to possibly middle Emsian age. The palynological analysis of the Jaciara section is completed herein with the analysis of the marine fraction, composed of highly abundant and diverse organic-walled phytoplankton, with 222 species recognized. Preservation and abundance of some species, that were previously informally described or mentioned, are here formally described. Additionally, two new species are instituted: Pterospermella jaciarense sp. nov. and Florisphaeridium brasiliensis sp. nov. The phytoplankton species, such as Bimerga paula, B. sp. aff. B. bensonii, B. nuda, Cordobesia oriental, C. uruguayensis, Palacanthus ledanoisii, Pyloferites escobaides, P. paranaensis and Winwaloeusia distracta, recorded in the lower part of the section, indicate a late Pragian age, in coincidence with the miospore age. Navifusa spp. and Pterospermella pernambucensis first appear in the middle part of the studied section, suggesting an Emsian age, as do the miospores. The diversity and preservation quality of the phytoplankton tend to decrease towards the top of the section, probably related to a general shallowing trend.

Pollen and Spores Recovery in Tunga Buzu Carbonaceous Shale Type Section Member: Significance in Sequence Stratigraphy, Age Dating and Paleoenvironment Deduction of the Early Miocene Gwandu Formation, Sokoto Basin, Northwestern Nigeria

Feld samples were collected from an outcrop at Tunga Buzu with the intention of comparing field relationship between the claystone member and the underlying carbonaceous shale Type Section for palynological study. The study was carried out in order to determine the geologic age relationship of the facies sequence, sequence stratigraphy and paleoenvironment of deposition of the sediments. Lithological description of the beds follows notation of colour, facies composition, texture, fossil content, structure and post depositional diagenetic effects. Laboratory preparation of palynological slides involved decarbonisation, sample digestion using hydrofluoric acid, sieving with 10µm mesh, bleaching of organic debris with nitric acid, maceral separation with zinc bromide, rinsing of separated maceral with ethanol and final mounting of the organomaceral on the slides for microscopic analysis.The carbonaceous shale is light grey in colour, fissile, carbonaceous, slightly bioturbated and ferruginized. Pollen, spores, dinoflagellates and algae were recovered from samples N1-N4. The samples N1-N3 are claystone samples characterised by relatively low assemblage assemblage of miospores with downhole increase in dinoflagellate cysts. The carbonaceous shale (sample N4) is relatively rich in palynomorphs with corresponding high palynomorph population and diversity compared with the claystone facies. Both the claystone and carbonaceous shale contain marker fossils such as Striamonocolpites sp., Retibrevitricolporites obodoensis, Verrutricolporites sp., Praedapollis sp., Belskipollis elegans and Peregnipollis nigericus; indicative of Early Miocene age. The litho-sequence of claystone and carbonaceous shale indicated alternation of continental and marginal marine deposits characterised by paucity and preponderance of peridinacean dinocysts. This suggests eustatic change in sea level of continental Lowstand Systems Tract (LST) and marginal marine Transgressive Systems Tract (TST) deposits respectively. The Tunga Buzu Carbonaceous Shale Type Section constitutes a member of the Early Miocene Gwandu Formation of the Sokoto Basin, Nigeria.

Appalachian coal bed palynofloras: changes in composition through time and comparison with other areas

Abstract This paper presents a summary of palynological data for Pennsylvanian age coal beds in the Appalachian Basin, discussed primarily from a biostratigraphic perspective. Coal bed palynofloras of Lower Pennsylvanian through early Permian age are compared and correlated with miospore assemblage zones established for western Europe, and the Eastern Interior (Illinois) and Western Interior Basins of the mid-continent USA. Lower Pennsylvanian palynofloras, which are dominated by lycopsid spores, are correlative with the Langsettian of western Europe and the Morrowan of the Eastern and Western Interior mid-continent USA Basins. Stratigraphically useful palynotaxa include Dictyotriletes bireticulatus , Radiizonates striatus , Schulzospora rara , Granasporites medius , Laevigatosporites minor and Endosporites globiformis . Middle Pennsylvanian palynofloras change through time, being lycopsid dominant in the lower part and more heterogeneous in the middle and upper parts with increased contributions from other Pennsylvanian plant groups. They are correlative with the Duckmantian, Bolsovian and Asturian of western Europe and the Atokan and Desmoinesian of the Eastern and Western Interior mid-continent USA Basins. Stratigraphically useful palynotaxa include Secarisporites remotus , Microreticulatisporites sulcatus , Vestispora fenestrata , Triquitrites sculptilis , Laevigatosporites globosus , Radiizonates difformis , Torispora securis , Triquitrites minutus , Mooreisporites inusitatus , Murospora kosankei , Thymospora pseudothiessenii and Schopfites dimorphus . Upper Pennsylvanian and lower Permian coal beds in the Appalachian Basin, in contrast to their Lower and Middle Pennsylvanian counterparts, are strongly dominated by tree fern spore palynotaxa. Palynofloras correlate with the Stephanian and Autunian of western Europe and the Missourian, Virgilian and Wolcampian of the Eastern and Western Interior mid-continent USA Basins.

Palynological analysis of the lower member of the Hongguleleng Formation and discussion of the Frasnian/Famennian boundary in Western Junggar, NW China

Palynological investigations have been carried out on samples from the Upper Devonian Hongguleleng Formation of Western Junggar, Xinjiang, NW China. In total, 26 miospore species belonging to 19 genera and 28 acritarch species assigned to 19 genera have been recognized from the lower member of the Hongguleleng Fm. in the Bulongguoer section. The palynofloral assemblages, in particular the miospore taxa, are similar to those from the eastern European early Famennian Corbulispora vimineus–Geminospora vasjamica (VV) and Cyrtospora cristifer–Diaphanospora zadonica (CZ) miospore biozones, albeit quantitatively and qualitatively depauperate. The miospore assemblage zone is also consistent with the previous zonal schemes in light of brachiopod and conodont fauna assemblages, as well as carbon isotope geochemistry, that indicates a correspondence to the Palmatolepis crepida conodont Biozone. Part of the earliest Famennian Corbulispora vimineus–Geminospora vasjamica (VV) (more or less equivalent to the Palmatolepis triangularis conodont Biozone) miospore Biozone is most likely to be missing in the Hongguleleng Fm. of the Bulongguoer section. The palynostratigraphy and sedimentary sequence in Western Junggar are very similar to those from some other regions of western and eastern Europe, which increases the knowledge of the evolution of the paleoclimate, paleogeography and regional sedimentary environment of the Central Asian Orogenic Belt (CAOB), Eastern European Platform, and Laurussia.

New data on the palynology of the Triassic–Jurassic boundary of the Silves Group, Lusitanian Basin, Portugal

New evidence is presented on the Triassic–Jurassic boundary in the northern Lusitanian Basin, Portugal, based on miospore assemblages from a composite Upper Triassic to Lower Jurassic succession of the Silves Group. The latter comprises, from base to top, the Conraria, Penela, Castelo Viegas and the Pereiros formations. Three informal palynological zones have been documented and compared with coeval palynozones from West and South Europe providing new biostratigraphic data to detail the age of the lower and upper formations of the Silves Group and to review previous age attribution.A Norian, possibly earliest Rhaetian age, is documented for the Conraria Formation on the basis of a palynological assemblage referable to the Classopollis meyerianus–Granuloperculatipollis rudis (CG) zone. The Penela and Castelo Viegas formations did not allow a palynostratigraphic revision, due to the not promising lithology for palynological studies. The Pereiros Formation is dated on the basis of microflora assemblages referable, from bottom to top, the Ischyosporites variegatus–Kraeuselisporites reissingeri (IK) zone of late Rhaetian–earliest Hettangian age and Pinuspollenites minimus (Pm) zone of Hettangian age. The discontinuity between the underlying Castelo Viegas Formation and the overlying Pereiros Formation did not allow to define the lower boundary of the IK palynozone. The Triassic–Jurassic boundary lies in the lower part of Pereiros Formation within the IK zone. The microflora assemblages from the Lusitanian Basin show close affinity to those of eastern N America and western Tethys areas.

Age revision of Carboniferous rocks in the northern part of the Intra-Sudetic Basin (SW Poland) based on miospore data

Palynostratigraphic studies of the Carboniferous strata of the Szczawno and Walbrzych formations, outcropping in the vicinity of Walbrzych in the northern part of the Intra-Sudetic Basin, are reported. Rocks of the Szczawno Formation in a section near Konradow had earlier been assigned to the Upper Visean, while rocks of the Walbrzych Formation in the Bialy Kamien section were included to the Lower Namurian [the Stenozonotriletes triangulus – Rotaspora knoxi (TK) Miospore Zone]. This study describes abundant palynological material with many taxonomically diverse miospore assemblages from these rocks, allowing precise palynostratigraphic conclusions. These showed that the rocks of the Szczawno Formation studied should be referred to the lower part of the Serpukhovian [ Verrucosisporites morulatus (Vm) Subzone], correlated with the lowest Namurian, while rocks of the Walbrzych Formation from Bialy Kamien belong to the Lower Bashkirian [ Lycospora subtriquetra–Cirratriradites rarus (SR) Subzone], correlated with the Upper Namurian A. These results indicate that the rocks from both sections studied are younger than they were earlier believed. This revises the age of the Szczawno and Walbrzych formations in the northern part of the Intra-Sudetic Basin which belong to four miospore zones, from Vm to SR, corresponding to the Serpukhovian and lowermost Bashkirian (Namurian A corresponding to the Pendleian to Alportian of British chronostratigraphy).

Palynofacies analysis and depositional environments of Upper Cretaceous sediments in the ST‐9H well, offshore South Tano Basin, Western Ghana

Palynofacies analyses were carried out on 43 cutting samples from the ST 9H well in the Tano Basin, with the view of reconstructing the palaeoenvironment of the Upper Cretaceous sediments in the well. The stratigraphic distribution of the palynofacies assemblages defined four palynofacies units. Palynofacies PA reflects deposition in near shore/shallow marine (inner neritic) environment under distal dysoxic‐anoxic shelf condition. Palynofacies PB was deposited in an inner–middle neritic environment under mud‐dominated oxic shelf conditions, Palynofacies PC in an open marine (outer neritic) environment under distal suboxic‐anoxic basin conditions, and Palynofacies PD in a proximal–marginal marine environment under dysoxic‐anoxic basin conditions. These palynofacies assemblages (PA–PD) are characterized by kerogen types II (oil prone), III‐IV (gas prone), II > I (oil prone), and III (gas prone), respectively. Marker dinoflagellate and miospore assemblages recovered from the sediments –are indicative of a Campanian–Maastrichtian age. The palaeofloral association and the perideanacean dinocysts assemblage are typical of Senonian Palme Province and the Malloy suite, respectively. These assemblages are indicative of a warm and humid tropical‐subtropical climatic condition.

Palynostratigraphic reassessment of the Late Devonian of Bjørnøya, Svalbard

A comprehensive study of the Late Devonian palynostratigraphy of Bjørnøya, Svalbard Archipelago is presented. A total of 61 samples collected from 10 outcrops located along the eastern coast of the island were analyzed for palynology yielding a mid- to latest Famennian age. A reassessment of the existing palynostratigraphy of the Ursa Sandstone Unit of the Røedvika Formation was undertaken. As no independent age control exists for this succession, the palynological assemblages were correlated to well-calibrated palynological zonations from the Eastern and Western Europe. The middle to upper part of the Vesalstranda Member and the Kapp Levin Member were assigned a mid- to late Famennian age (CVa to VF biozones), and the middle to lower-upper part of the Tunheim Member was dated as latest Famennian in age (LL to LN biozones). For the first time, a palynological age was assigned to the upper part of the Kapp Levin Member. Correlation with other Arctic areas show close resemblance to Late Devonian assemblages from Europe and the Arctic region. However, differences in the stratigraphical ranges of several taxa were identified. In terms of Late Devonian paleophytogeographic provinces the miospore assemblages are assigned to the Northern Euroamerican Cornispora varicornata Realm for the mid-Famennian. A more cosmopolitan trend was recognized for the latest Famennian (Strunian), with assemblages including abundant Retispora lepidophyta. The paleobotanical affinities of the palynomorphs reveal a flora of lycopods and progymnosperms occupying this area during the Late Devonian, with Retispora lepidophyta becoming a common element in the latest Famennian.

Paleoenvironmental interpretation and palynoflora of Devonian–Carboniferous subsurface sections from the eastern part of the Moesian Platform (Romania)

Palynomorph assemblages and palynofacies analyses have been performed on several core samples from the Devonian–Carboniferous deposits identified in five wells located within the eastern region of the Moesian Platform. The investigated sections include, in ascending stratigraphic order, the Ţăndărei, Smirna, Călăraşi and Vlaşin formations. Based on the stratigraphic distribution of key taxa identified (miospores, chitinozoans, acritarchs), seven biozone intervals (four for the Devonian and three for the Carboniferous) have been recognized. The oldest samples were dated as being part of the micrornatus–newportense (MN) – lower part of breconensis–zavallatus (BZ) Assemblage Zones (Early Devonian), while the younger ones are assigned to the kosankei–varioreticulatus (KV) – nobilis–junior (NJ) Assemblage Zones (Pennsylvanian). Palynofacies observations suggest a fairly distal depositional environment during the period between the Lochkovian and Pragian times, followed by some proximal/fluvio-deltaic conditions in Emsian–Early Eifelian (top of the Ţăndărei Formation). The upper Tournaisian to Serpukhovian sedimentary rocks of the Călăraşi Formation and lower part of Vlaşin Formation were deposited in inner neritic environments. Mud-dominated dysoxic/anoxic conditions of the Bashkirian, abruptly transitioned to deltaic deposition and oxidizing environments that persisted to the Moscovian.The Early Devonian terrestrial palynoflora is dominated by trilete spores which belong to lowland vegetation (vascular plants), the latter preferring areas with open connections via rivers to marine sedimentary basins. Carboniferous samples yielded only terrestrial miospores of various types of arborescent and herbaceous lycopsids and ferns, suggesting different habitats such as non-flooded wetlands or swamps within coastal plain and continental interiors. These assemblages of Carboniferous miospores are an indication of neutral-humid climatic conditions which existed at the time of deposition.

The first Cretaceous megaspores from Ukraine

The first megaspores recovered from Ukrainian Lower Cretaceous strata are described and illustrated by reflected light and scanning electron micrography. Four lycopsid megaspore taxa are identified in core samples from north of Kherson (Khersons'ka Oblast), in the Black Sea Basin, southern Ukraine. Miospore assemblages recovered from the same samples reveal a slightly higher diversity of lycopsid microspores and, in conjunction with previous foraminiferal biostratigraphy, indicate an Aptian–Albian age for the strata. The megaspore suite shares genera with mid-Mesozoic assemblages from widely distributed parts of the world, but most of the Ukrainian specimens have subtle morphological differences from congeneric forms established in other regions. The megaspores accumulated in fluvial floodplain facies and highlight the potential of this region for investigating other Cretaceous mesofossils including early flowers.

Biostratigraphy and paleoecology of Asbian–Brigantian (Mississippian) miospores from Berwick-upon-Tweed, Northumberland, UK: Preliminary results

Well-preserved, late Visean miospore assemblages from the coastline south of Berwick-upon-Tweed, Northumberland, UK, show a sequence of palynostratigraphic events stretching from the mid Asbian to the Brigantian. The assemblages belong to the Raistrickia nigra–Triquitrites marginatus (NM) and Tripartites vetustus–Rotaspora fracta (VF) biozones. Several taxa previously only recorded from pre-Brigantian strata (including Murospora parthenopia and Verrucosisporites eximius) are recorded from Brigantian rocks. The section is composed of “Yoredale” cycles reflecting cyclical changes in sea level. These features exerted control over the distribution of miospores in the section with notable trends in the vertical distributions of miospores indicative of forest mire and colonizer vegetation. Miospores representing forest mire vegetation dominate in coarser-grained rocks deposited in more proximal environments and have similar distribution patterns to rounded-triangular miospores. Conversely, non-forest mire vegetation is better represented in more proximal depositional settings, as are rounded-triangular miospores. Some samples contain mutated examples of the miospore Tripartites vetustus Schemel 1950. Mutagenesis is probably related to some, unspecified ecological stress.

Palynology, Palynofacies and Geochemistry on the Triassic Casa Piedra Formation, Rincón Blanco Group, Argentine Precordillera: Depositional Environment and Hydrocarbon Potential

This paper presents the study of the kerogen recovered from the Casa de Piedra Formation. The analysis includes systematic palynology, palynofacies, organic geochemistry (total organic carbon – TOC – and pyrolysis Rock-Eval) and inorganic geochemistry (X-ray fluoroescence). A new spore species is introduced: Rugulatisporites claudiae sp. nov. Three palynofacies are defined throughout the unit. The uppermost horizons, P1, fluvial in origin, include low TOC contents, a kerogen Type III, mostly terrigenous-derived, and a relatively diverse miospore assemblage largely dominated by disaccate pollen grains of umkomasiaceous/ peltasperm affinity; the K/Rb ratio is high, V is scarce, and Mo is absent. The middle, lacustrine section, P2, includes relatively high TOC values, a mostly amorphous rich kerogen Type II, and abundant Botryococcus sp.; the K/Rb ratio is relatively low, V is high, and Mo is present. The kerogen at the basalmost horizon, P3, is similar to the uppermost section, but includes relatively high percentages of amorphous organic matter and Botryococcus sp.; the K/Rb ratio is the lowest of the section, V is relatively low, and Mo is absent. The kerogen from the lacustrine P2 exhibits a moderate hydrocarbon genetic potential (ca. 3 to 31 kg HC/ ton). doi: 10.5710/AMGH.31.05.2019.3247

Higher plants and miospore assemblage of Burtnieki Regional Stage (Givetian) of South Estonia

The flora of Joosu Quarry (Estonia) is additionally studied from the deposits of Abava Member of Givetian Burtnieki Regional Stage. Its systematic composition has been expanded to four species instead of the previously known single species. The predominance of representatives of Pseudosporochnus and presence of single lycopsid is reported. The diagnostic features of Pseudosporochnus species are revealed and the specific composition of this genus is inspected. Spores from sporangia of Pseudosporochnus for the first time along with the miospore assemblage from the deposits of Abava Member, containing plants are allocated and illustrated. The age of Abava Member deposits is determined by macroflora as the possible Lower Givetian. Dispersed miospores allowed us to take Abava Member to the Geminospora extensa (EX) Zone which corresponds to the modern view the lower and middle parts of Givetian.

Palynology of the Lower Cretaceous Hundleby Clay Member of the Claxby Ironstone Formation in eastern England and its biostratigraphic and palaeoenvironmental significance

Palynomorph assemblages recovered from five samples of the Hundleby Clay Member of the Claxby Ironstone Formation contain abundant dinoflagellate cysts and miospores (spores and pollen grains). The cyst assemblages are sufficiently diverse to enable an age determination of early Valanginian for all five samples, although it is possible that evidence from the highest two samples indicates a younger age, but no younger than earliest Hauterivian. The miospore assemblage is consistent with these suggestions. A close comparison can be made with palynomorph assemblages from the Speeton Clay Formation at outcrop in East Yorkshire, and indicates a possible correlation with Beds D4–D3 ( Paratollia – Polyptychites ammonite zones), supporting the age determination. The overall composition of the palynological matter recovered from each sample, i.e. their palynofacies, suggests that the whole of the sedimentary succession accumulated in a nearshore marine setting, with deposits at the base of the exposure (samples 1 and 2) reflecting a more distal shelf environment than those from higher up and at the top of the section examined (samples 4, 5 and 3).

Vegetation and climate of the central and northern Qinghai–Xizang plateau from the Middle Jurassic to the end of the Paleogene inferred from palynology

The collision between India and Eurasia and the subsequent uplift of the Qinghai–Xizang plateau region of the Eurasian continent during the latest Mesozoic and Cenozoic had a significant environmental impact on the region. Understanding the vegetation of both palaeocontinents prior to the collision is crucial for interpreting the evolution of their floras and climatic changes during this period. The composition of the vegetation and climate of the plateau from the Middle Jurassic until the end of the Oligocene are inferred herein from the composition of 14 palynofloras and compared with other regions of China. The palynofloras are similar to those of eastern and northwestern parts of China but bear their own unique features brought about by differing climatic influences. Overall, a warm–hot, arid–semi-arid climate prevailed over the plateau during most of the period from the Middle Jurassic until the end of the Cretaceous. The climate cooled and humidity increased in the Paleogene, and especially during the Oligocene. The long-term climatic change in the Qinghai–Xizang plateau region of the Eurasian continent during the Middle Jurassic–Paleogene that is indicated by the miospore assemblages is broadly comparable to the isotope-based SST (sea-surface temperature) changes that have been identified. It is apparent that climatic changes on a global scale were primarily responsible for controlling the composition and distribution of the vegetation on the plateau; no monsoon features are detectable in the northwestern interior of China. A maximum estimation of 2890 m surface palaeoelevation is inferred for the central and northern plateau during the Oligocene based on vegetation analysis, which is lower than previous estimations based on oxygen isotope and coexistence analyses. The elevation of the southern part of the study area, i.e. the area south of the Gandise Mountains, was low, close to sea-level.

Triassic vegetation and climate evolution on the northern margin of Gondwana: a palynological study from Tulong, southern Xizang (Tibet), China

We present vegetation reconstructions based on an almost complete succession through the Triassic of Tulong, Nyalam County, southern Xizang (Tibet), China. The Permian and earliest Triassic samples were barren of palynomorphs, however, in overlying strata we identified well-preserved and diverse miospore assemblages. Seven pollen and spore zones spanning the Olenekian to the Rhaetian were recognized. These palynological zones were amalgamated into three floral stages that comprise distinct vegetation types: (1) an early Olenekian lycophyte-dominated flora with common pteridosperms, indicative of a warm and dry climate; (2) a late Olenekian transitional flora composed of abundant conifers with low abundances of lycophytes, signifying a decrease in temperature and increase in humidity; (3) a Middle to Late Triassic mature conifer-dominated flora with diverse sphenophytes, ferns and cycadophytes, indicative of a stable, temperate and humid climate. The changes in vegetation and climate tentatively correlate with the rifting of northern Gondwana, suggesting that regional tectonics was a contributive driving factor to local floral community change.

Stratigraphy of the Northern Pulo do Lobo Domain, SW Iberia Variscides: A palynological contribution

We present palynological results from the northern sector of the Pulo do Lobo Domain, combining sections studied in Portugal and Spain. A total of 139 samples were studied, of which 56 are positive for palynology. The first age determination for the Pulo do Lobo Formation was achieved, indicating a mid-Frasnian age (Verrucosisporites bulliferus and Pustulatisporites rugulatus). The sediments of Peramora Mélange (Spain) yielded the same palyno-assemblage as that of the Pulo do Lobo Fm. and are interpreted as a part of this formation. The Ribeira de Limas Fm. also yielded mid-Frasnian miospore assemblages, indicating the same age as the Pulo do Lobo Fm. The Santa Iria and Horta da Torre formations present spore assemblages assigned to the late Famennian in both Portugal and Spain. The phyllites interbedded with the quartzites of the Alájar Mélange yielded a palyno-assemblage late Famennian in age that can be correlated to the Horta da Torre Fm. Therefore, the Alájar quartzites are interpreted as a lateral equivalent of the Horta da Torre Fm. in Spain. The palynological results obtained for the units of the northern sector of the Pulo do Lobo Domain are highly consistent and in agreement with stratigraphic mapping and structural interpretations. A detailed discussion of the palynological versus geochronological ages based on detrital zircons is included in this study. The palynological results and their comparison with the worldwide Upper Devonian palynological record suggest a close affinity with NW European palynofloras, placing the Pulo do Lobo Domain within the Avalonian paleobiogeographical province.

Palynology of Jurassic (Bathonian) sediments from Donbas, northeast Ukraine

A palynological and sedimentological study of an outcrop succession adjacent to the village of Kamyanka within the Kharkiv region of northeast Ukraine was carried out. The successions occur within the Dnieper–Donets Basin, which hosts vast successions (> 20 km) of post mid-Devonian strata and is one of the main hydrocarbon-producing basins in Europe. Middle Jurassic sandstones, siltstones and claystones represent the sedimentary successions at the Kamyanska locality. Few palynological studies have been performed on the Jurassic of Ukraine and even fewer presented in the international literature. Thirty spore taxa and 21 pollen taxa were identified, together with taxa kept in open nomenclature (e.g. bisaccate pollen). Two palynological assemblages were identified within the Kamyanska succession (assemblages A and B) dated as Bathonian. Assemblage A is dominated by the fern spores (Cyathidites and Osmundacidites) and gymnosperm pollen produced by Cupressaceae (Perinopollenites elatoides), ginkgophytes/Cycadales/Bennettitales (monosulcates) and Cheirolepidiaceae (Classopollis). Assemblage B differs in also comprising high abundances of Gleicheniidites and higher percentages of Pinuspollenites and Araucariacites compared to assemblage A. Another difference between the two units is the high relative abundance of seed fern pollen (Alisporites) in the upper part of assemblage B. The thermal alteration index (TAI) of the palynomorphs is estimated to range from 3 to 3.5, indicating a burial depth corresponding to the mature main phase of liquid petroleum and, to some extent, gas generation. Comparisons between the miospore and macrofloral assemblages show that the palynoflora and macroflora are strongly similar at broad taxonomic levels. Importantly, the miospore assemblages described here compare well with European Middle Jurassic assemblages indicating limited provincialism, with similar vegetation extending from eastern Ukraine and across most of Western Europe.