Palynological Assemblages Research Articles

Kimmeridgian–Volgian Palynological Assemblages of the Eganovo Section (Moscow Region) and Their Possible Application for Biostratigraphy, Correlation, and Facies Analysis

Kimmeridgian–Volgian Palynological Assemblages of the Eganovo Section (Moscow Region) and Their Possible Application for Biostratigraphy, Correlation, and Facies Analysis

Middle Triassic lake deepening in the Ordos Basin of North China linked with global sea-level rise

The Yanchang Formation was deposited during the Middle Triassic in a vast lacustrine basin in the modern Ordos Basin and is a main target for hydrocarbon exploration in Central China. It is divided, based on sedimentary cycles and lithology , into the Chang 10 (the oldest) to Chang 1 (the youngest) members. During the deposition of the Chang 7 Member, the Ordos lake system reached its maximum depth and large volumes of organic-rich sediments were deposited. The evolution of the Ordos Basin sedimentary system during this phase is, however, not completely understood, and uncertainty still exists as for the chronostratigraphy of Chang 7 Member. We acquired palynological markers and palynofacies and a high-resolution δ 13 C org record through the entire Chang 7 Member, and a ID-TIMS 206 Pb/ 238 U date of 240.95 ± 0.033 Ma from a volcanic ash bed in the middle of this Member. These imply that the maximum deepening phase of the lacustrine system was during the earliest Ladinian . Evidence of marine influence in the Ordos Basin at that time and comparison to the sea-level oscillations observed in Western Tethys suggest that a global eustatic rise and highstand may have played a role in determining lake-level variations. • We report a zircon age of 240.950 ± 0.033 Ma from the middle portion of Chang 7 Member that indicates an early Ladinian. • The identified palynological assemblage also supports a late Middle Triassic age for Chang 7 Member. • The maximum expansion of the Ordos lake was probably influenced by the early Ladinian maximum in eustatic sea level.

Palynological assemblage of the Lower Devonian of Hezhang, Guizhou, southwestern China

Abundant and diverse palynomorphs are firstly recovered from the Lower Devonian Danlin Formation of the Caoziping Section, Hezhang, Guizhou Province, southwestern China. A palynological assemblage, summarized as Retusotriletes triangulatus–Latosporites ovalis–Apiculiretusispora plicata (TOP) assemblage, contributes a better understanding of the Early Devonian flora of South China. Hezhang TOP palynological assemblage is dominated by trilete spores and includes 36 genera and 72 species of spores. Qualisaspora sinuata and Gneudnaspora divellomedia var. divellomedia, are for the first time discovered from the Lower Devonian of China. The TOP assemblage dates the Danlin Formation as Pragian to early Emsian (Early Devonian) and indicates a coastal palaeoenvironment with co-occurrences of acritarchs and scolecodonts. As a supplementary part of Lower Devonian palynological flora of South China, the Hezhang palynological assemblage shows similarities to those in Euramerica, northern Africa, Saudi Arabia, and Australia in spore components and abundances, suggesting closely-related Early Devonian floras of South China, Euramerica, and Gondwana.

Hydrocarbon source rock potential and paleoecological studies of the Surma sediments of Manipur region, India: Insights from palynology and organic geochemistry

The palynological assemblages, organic content, Rock-Eval analysis and stable isotope ratios of three outcrop sections were studied of the Miocene Surma Group in Indo-Myanmar Range to characterize the lithology, and assess kerogen types. The well-preserved palynological assemblages from the ATF, AAN and AAS sections indicate a tropical-subtropical climate with humid conditions. The δ13C values of the organic matter in these sections ranges from −19.92 to −26.08 ‰, indicative of C3 vegetation. Among these sections, our data indicates ATF has the driest and AAN wettest climate. Results from Rock-Eval analysis suggests that all the rock samples have poor organic richness (TOC < 0.5 %) and poor hydrocarbon generation potential (S2 < 0.5 mgHC/g). The organic matter of these samples is mixture of Type III and Type IV. The Tmax and Productive Index values support the results of visual kerogen analysis suggesting immature with mature and contaminant zones. The Surma sediments are poor source of gaseous hydrocarbons based on the results of this work.

PALYNOLOGY OF THE PERMIAN OF THE MAKHTESH QATAN-2, RAMON-1 AND BOQER-1 BOREHOLES ARQOV FORMATION, NEGEV, ISRAEL

Palynological assemblages from cores 11 to 14 of Makhtesh Qatan-2, core 3 of Ramon-1 and core 3 of Boqer-1 boreholes from the Arqov Formation of the subsurface of the Negev, southern Israel, suggest that at least part of the Arqov Formation can be characterised by Cedripites priscus, Reduviasporonites chalastus and particularly Pretricolpipollenites bharadwajii, while the Saad Formation contains a slightly less diverse assemblage lacking the three taxa above. Palynological evidence is broadly consistent with other palaeontological evidence suggesting that the Saad Formation is in part likely to be Wuchiapingian in age, and the Arqov Formation is at least in part Changhsingian. These conclusions are tentative because core data is restricted to very few well penetrations and a total lack of surface exposure of the Permian.

Pliocene Lythrum (loosestrife, Lythraceae) pollen from Portugal and the Neogene establishment of European lineages

The fossil record of Lythrum is scarce and every new find brings an extra piece of the puzzle to the obscure phytogeographic history of this genus. Lythrum pollen is unique and has the potential to be recognized in palynological assemblages. Therefore, the few pre-Holocene fossil records are all pollen described from North America, Russia, and Europe. The European records are both most numerous and geologically younger than those from other parts of the Northern Hemisphere. Earliest European Lythrum pollen records are of late Miocene age and parallel to starting crown group radiation in the Eurasian clade of Lythrum. European Miocene to Pliocene Lythrum pollen morphology is comparable to that of extant species. Interestingly, the late Miocene expansion of Lythrum into Europe coincides with the decline of Decodon, and Lythrum appears to replace Decodon in late Neogene fossil palynological assemblages.

A new Late Devonian flora from Sonid Zuoqi, Inner Mongolia, northeastern China

AbstractThe Silurian and Devonian plant fossil record is the basis for our understanding of the early evolution of land plants, yet our appreciation of early global phytogeographic evolution has been constrained by the focus of most studies on deposits from Europe, North America, and, more recently, South China. Devonian plants have been recorded rarely from northeastern China, and among previous records, few plants have been illustrated and formally described. In this article, megafossil plants representing a Late Devonian-aged (probably Famennian) flora are described from a locality at northern Sonid Zuoqi, Inner Mongolia, NE China. The flora includes Melvillipteris sonidia new species, Archaeopteris sp., and fragments of some other plants. The new plant shows main axes and two orders of lateral branches. The first-order branches of this plant show a typical zigzag appearance and are borne in pairs on main axes. Second-order branches are straight or slightly flexed, and are borne helically or alternately on first-order branches. Sterile ultimate appendages and fertile structures of M. sonidia n. sp. are borne alternately on second-order branches. An associated palynological assemblage, as well as U-Pb ages of detrital zircon grains from adjacent horizons, are also reported, indicating a Late Devonian age in accord with the megafossil plants. The present study contributes to our appreciation of the Devonian floristic diversity of the Xing'an Block, and, through our review of the record of early vascular plants from NE China, more broadly to the understanding of the mid-latitude vegetation of the Northern Hemisphere during the Late Devonian.

An investigation of a Devonian/Carboniferous Boundary section on the Bolivian Altiplano

AbstractThe Devonian/Carboniferous Boundary (DCB) interval is associated with mass extinction, isotope excursions and a short glacial episode. This study investigates how boundary extinction and environmental change is expressed in the glacial high-palaeolatitudinal record of the Bolivian Altiplano (western Gondwana). A latest Devonian and early Carboniferous section has been investigated using sedimentology, palynology, total organic carbon and bulk δ13Corganic. The Colpacucho Formation is a Late Devonian shelfal–marine siliciclastic sequence. It is overlain in the study area by a unit of coarse sandstones and sandy diamictites, interpreted as glaciomarine. This distinctive glaciomarine unit is at least 7 km wide and 60–120 m thick with a variably incisive basal contact (&lt;100 m). It is of very latest Famennian age and is a stratigraphic equivalent of proven glacigenic deposits across central South America. The offshore marine Kasa Formation overlies the glacigenic unit above a basal flooding surface. The DCB is 12 m above this flooding surface on the last occurrence of Retispora lepidophyta and significant palynological assemblage changes. This includes the loss of the Umbellasphaeridium saharicum phytoplankton bioprovince, endemic to Gondwana. Marine and terrestrial palynological extinctions are synchronous with a 2 ‰ positive carbon isotope excursion interpreted to be reflective of changes in organic matter delivery and preservation during an interval of environmental stress. These results inform wider debates on global environmental change and mass extinction at the DCB.

Facies analysis, petrography, and palynology of the Pirara Formation (Upper Jurassic-Lower Cretaceous) - Tacutu Basin (Roraima, Brazil)

The Tacutu Basin formed from the rifts system that occurred in the Caribbean region during the Mesozoic and culminated with in the opening of the North Atlantic Ocean. It evolved as a half-graben inserted in the Guiana Shield north of the Amazonian Craton. The Pirara Formation corresponds to the rift phase of the evolution of this basin, however the studies characterizing this unit are very scarce and little accurate due to the absence of outcrops. Therefore, there is much debate about the origin and depositional environment of the Pirara Formation, as some authors argue that the basin was episodically connected to the sea during the rifting, whereas others claim that was a continental-lacustrine environment, under arid to semi-arid climatic conditions. This work was based on investigations carried out on recently drilled rock cores of the Pirara Formation, which provides substantial new information regarding lithological and sedimentological data. The main objective was to characterize the lithofacies petrography palynofacies and constrains the paleoenvironmental interpretation of this unit. Three main lithofacies were identified: marlstone, siltstone, and black shale, with the latter yielding TOC content between 5% and 13.7% and organic matter consisting of phytoclasts, palynomorphs, and amorphous particles. Highly hypersaline conditions are indicated by the presence of pseudomorphs of evaporitic minerals, occurring in the marlstone and siltstone facies. Conversely no marine components take place in the palynological assemblages. The results demonstrate that the Pirara Formation represents a playa lake environment that evolved in the Southern Caribbean region in the Late Jurassic-Early Cretaceous during the opening of the Central Atlantic Ocean.

Dicroidium (Zuberia) zuberi (Szajnocha) Archangelsky from exceptional Carnian leaf litters of the Ischigualasto Formation, westernmost Gondwana

ABSTRACT The Carnian Ischigualasto Formation of Argentina is known worldwide by its great abundance of palaeovertebrates, including the oldest dinosaurs and a palaeoflora represented by Onslow-type palynofloras, permineralizations, and compressions of foliage. However, thin deposits composed exclusively by cuticles are also preserved in this unit. This unusual type of preservation, where cuticles have accumulated as thousands of superimposed specimens without sediment between them, represents leaf litters of autochthonous or parauchthonous origin. Leaf litters are preserved into periodically flooded abandoned fluvial channels, which received accumulations of leaves from the riparian vegetation that, combined with pyroclastic inputs, generated ideal diagenetic conditions for their fossilisation. The excellent preservation of the cuticles allows the description of fine epidermal and cuticular features. One of the most common species in the Ischigualasto Formation, Dicroidium (Zuberia) zuberi (Szajnocha) Archangelsky, is described using optical and scanning electronic microscopy. Cuticles are thick, amphistomatic, with stomata sunken and randomly distributed, and with papillae on epidermal and subsidiary cells. Comparisons with previous hypostomatic records of the species suggest phenotypic plasticity of this Umkomasiaceae species. Palynological assemblages recovered from the same deposits indicate humid conditions under a seasonal climate. The vegetation flourished after a biotic turnover dated at 228.91 Ma by radiometric method.

Reconstruction of the latest Eocene-early Oligocene paleoenvironment in the Hoh Xil Basin (Central Tibet) based on palynological and ostracod records

As the largest intracontinental basin in the Tibetan Plateau hinterland, the Hoh Xil Basin is an ideal area for exploring the coupled history of climate-tectonic relationships in the plateau's interior. However, the detailed paleoenvironmental research on the Hoh Xil Basin is quite insufficient. In this study, we collected palynological and ostracod samples from well-exposed Cenozoic lacustrine strata in the Hoh Xil Basin to reconstruct the paleoenvironment and paleoelevation of the Hoh Xil Basin. Based on the discovery of two key index fossils (Austrocypris cf. posticaudata and Lychnothamnus vectensis), we propose the latest Eocene-early Oligocene (latest Priabonian-earliest Rupelian) age for the strata of the Yaxicuo Formation in the Tongtianhe section. The palynological assemblage suggests that the Hoh Xil Basin was dominated by temperate broadleaved forest and that a warm climate prevailed in this region during the latest Eocene-early Oligocene. Roughly consistent with the overall warm climate confirmed by palynological evidence, the ostracod record indicates that a large freshwater lake existed within the warm environment of the Hoh Xil Basin during the latest Eocene-early Oligocene. By using the coexistence approach (CoA) to evaluate the fossil palynological assemblage, combined with the calibration of the effects of temperature differences and lapse rates, a paleoelevation of 2700 ± 200 m a.s.l. was estimated for the Hoh Xil Basin during the latest Eocene-early Oligocene, representing the height between the basin lake and the crests of the surrounding mountains.

Palynology of the Early to Middle Devonian Pescado Formation, Subandean Range, Salta Province, Argentina

We present the palynoflora recovered from the Pescado Formation in the Subandean Range, Salta Province, Argentina. The palynological assemblage comprises well-preserved marine and terrestrial palynomorphs, including cryptospores (one species), trilete spores (16 species), acritarchs (six species), prasinophytes (three species), and chlorophytes (three species). Based on the quantitative analysis and stratigraphic distribution of palynomorphs, two palynological associations are recognized (RC1, RC2). The presence of Dictyotriletes emsiensis morphon and Acinosporites apiculatus, together with Duvernaysphaera angelae and D. tenuicingulata, suggests a late Emsian–Eifelian age for RC1 and RC2. The studied assemblages contain many taxa in common with other coeval assemblages of Gondwana that confirm the paleogeographical relationships among the Argentine Precordillera, the Tarija Basin, and the southern Chacoparaná Basin in Uruguay. The relative abundance of the palynomorphs encountered suggests a marine depositional environment close to the paleo-shoreline for the RC1, and a more distal marine setting for the RC2, possibly nearshore, reflecting the Eifelian transgression. This event, already documented by different authors, is also recognized in the southern portion of the Tarija Basin.

Sedimentation, depositional environments, and hydrocarbon potential of the Maastrichtian-Paleocene Araromi Formation, eastern Dahomey (Benin) Basin, southwestern Nigeria

The Cretaceous sediments in southwestern Nigeria are host to one of the largest bitumen deposits in the world. In the current paper, an integrated study on sedimentology, palynology, and applied petroleum geochemistry of the Maastrichtian-Paleocene Araromi Formation was used to determine the depositional environments and hydrocarbon potentials of the formation on the eastern Dahomey Basin. Four sedimentary lithofacies were identified from core samples, namely, lower limestone (F1); medium to coarse-grained sandstone (F2); lower loosely consolidated sandstone (F3); and shale and siltstone (F4). Sedimentation in the eastern Dahomey Basin occurred mainly in fluvial and shallow-marine (shelf) environments. The palynological assemblages of the Araromi Formation reflect deposition in coastal through brackish water to shallow shelf environment with periods of localized wind-induced storms. The shale and siltstone samples of the Araromi Formation are characterized by total organic carbon (TOC) values of up to 2.50 wt % and S2 (hydrocarbon-generating potential) values ranging from 0.26 to 0.70 mgHC/g rock, indicating poor source rocks. Shales show poor quality and thermally immature organic matter at shallow depth and could neither have generated liquid hydrocarbon nor contributed to the heavy oil occurrence on the bitumen and tar-sand belt of eastern Dahomey (Benin) Basin.

High-precision U-Pb CA-ID-TIMS calibration of the Permian Lueckisporites-dominated assemblages in westernmost Gondwana: inferences for correlations

Palynology is one of the most useful tools for constructing biostratigraphic charts in the late Paleozoic basins of South America, but the lack of radiometric ages often makes it difficult to establish the precise age of the biozones. This paper focuses on two points: (i) the description of new Argentinian palynological assemblages referred to the Lueckisporites/Weylandites (LW) Biozone and (ii) the application of a new isotopic age that enables more confident large-scale correlations with the neighboring Paraná Basin of Brazil. The palynofloras were recovered from the upper part of the De La Cuesta Formation that crops out in the retroarc basin of the Paganzo Basin, more specifically obtained from mudstones intercalated with limestones, cherts, and tuffs interpreted as being deposited in a shallow water body. The assemblages are characterized by an abundance of bi-taeniate pollen grains of the Lueckisporites complex and multitaeniate pollen grains such as Lunatisporites, Protohaploxypinus, Striatopodocarpidites, Tornopollenites, and Vittatina. Colpate pollen grains are also represented by Marsupipollenites and Pakhapites. A U-Pb CA-ID-TIMS age of 278.84 ± 0.22 Ma, obtained from a tuff level interstratified with the fossiliferous strata, allows the age of the LW Biozone in the Paganzo Basin to be constrained for the first time and the adjustment of the record Lueckisporites virkkiae in Gondwana. Moreover, this date enables precise correlations with other basins, such as the San Rafael Basin (Yacimiento Los Reyunos Formation) in Argentina and the Brazilian Paraná Basin (Iratí Formation).

Low-latitude ?upper Barremian–lower Aptian palynoflora and paleovegetation of the Biyadh Formation (Arabian Plate, eastern margin of northern Gondwana): evidence for a possible cold snap

A palynological analysis of core and cuttings samples from successions assigned to the Biyadh Formation of Saudi Arabia in the Arabian Gulf (eastern margin of northern Gondwana) revealed diverse and well-preserved palynological assemblages including bryophyte and fern spores, gymnosperm and flowering plant pollen, dinocysts, and acritarchs. Palynological data corroborates earlier geological and stratigraphic models, indicating a ?late Barremianearly Aptian age. The fluctuations of dinocyst abundance and diversity proved extremely useful to detect fine-scale sea-level changes in carbonate platforms with episodic terrigenous inputs. In agreement with current understanding of dinocyst paleoenvironmental distribution trends, Cribroperidinium and Aptea? vannophora are restricted to inner neritic/?fluvial-influenced settings, while Spiniferites and Trichodinium have been confirmed as more open marine water (middle/outer neritic) indicators. The composition of the terrestrial assemblages is dominated by fluvially-transported spores, mainly released by ferns and probable tree ferns. The overall floral composition is considered to reflect a seasonal, humid, climate punctuated by episodic droughts. Recurrent increases in abundance of wind-pollinated cheirolepid and Araucariaceae pollen, observed in assemblages otherwise characterized by low dinocyst content, are interpreted to represent sea-level falls and basinward expansion/migration of conifer-dominated coastal vegetation. The abundance of the dinocysts Cepadinium variabilis and Pseudoceratium nohrhansenii sp. nov., previously recorded at higher latitudes, is interpreted to reflect the invasion of cooler/colder water masses, confirming a significant ?latest Barremian/early Aptian global cold episode, possibly related to the OAE1a event. The following new dinocyst taxa are described: Pseudoceratium nohrhansenii sp. nov. and Protobatioladium alhajrii sp. nov.

A transient south subtropical forest ecosystem in central China driven by rapid global warming during the Paleocene-Eocene Thermal Maximum

Rapid global warming during the Paleocene-Eocene Thermal Maximum (PETM) profoundly affected the marine and terrestrial environments. However, details of the climate and vegetation of subtropical and arid regions of central China during the hyperthermal event are poorly understood. Here, we report a palynological record from the black shale of the lowermost Yangxi Formation exposed in Songzi city, western Jianghan Basin, central China. Biostratigraphy, magnetostratigraphy and isotope stratigraphy indicate a PETM age for the sedimentary succession. The palynological assemblage was characterized by high abundances of diverse tropical and subtropical broadleaved tree pollen, providing strong evidence of a dense south subtropical forest ecosystem that once existed in the arid belt of central China during the PETM. The reconstructed climatic parameters indicate an extremely warm and humid south subtropical climate, with mean annual temperatures (MAT) ranging from 21 to 24 °C and mean annual precipitation (MAP) ranging from 1396 to 1997 mm. The reconstructed precipitation was surprisingly high for such an arid setting that widespread arid climate prevailed in central China at that time. These findings demonstrate that rapid global warming during the PETM significantly increased precipitation, leading to the growth of dense forest ecosystems as well as increasing lake eutrophication in central China. The changes to precipitation and terrestrial ecosystems during this warming event are considerably more significant than previously reported in other mid-latitude regions, and highlighting the need to consider regional geographic characteristics to fully understand how the environment responds to rapid global warming.

A new Late Triassic palynological assemblage from western Gondwana (Carrizal Formation, Marayes Basin, Argentina)

The Carrizal Formation, exposed in the Marayes-El Carrizal Basin (western Argentina), has been the focus of palaeobotanical studies since the late 1800s. The recent finding of well-preserved palyno­logical assemblages provides the first detailed studies about its palynofloras. In this paper, the 63 taxa identified in the unit are illustrated and discussed, as well as their stratigraphic distribution in equivalent palynological assemblages of Argentina. Some spore species are revised: Uvaesporites hammenii (Herbst) Césari, comb. nov., Retusotriletes wielandii (Jain) Césari, comb. nov. and Lundbladispora stellae (Herbst) Césari, comb. nov. The recognition of Cadargasporites baculatus de Jersey &amp; Paten emend. Reiser &amp; Williams, Craterisporites rotundus de Jersey, Enzonalasporites vigens Leschik, ­Leptolepidites argenteaeformis (Bolkhovitina) Morbey, Protodiploxypinus americus Dunay &amp; Fisher and Rugulatisporites permixtus Playford, among others, appears to be useful for local and intercontinental correlations. A Carnian age is proposed for the palynofloras.

U-PB ages and environmental evolution of the De La Cuesta Formation (late Paleozoic): Record of the Choiyoi Volcanism in the retroarc area of the Paganzo Basin, Western Gondwana

This paper examines the relationship between the sedimentation in the retroarc Paganzo Basin and the activity of the magmatic arc developed in the neighboring Andean Cordillera during the Late Pennsylvanian-Cisuralian. The temporal relationships between the Choiyoi Volcanism (Andean region) and the retroarc Paganzo Basin were investigated according to three lines of research: 1. Sedimentology and lithostratigraphy of the De La Cuesta Formation, 2. Geochronology and, 3. Biostratigraphy.Paleoenvironmental studies indicate that small alluvial fans (facies association A) and braided river (facies association B) deposits prevailed in the lower third of the De La Cuesta Formation, which includes a thin intercalation of shallow marine sediments only present in the western part of the area (facies association C). A progressive decrease in the energy of the fluvial systems occurred at the middle part of the unit, where dominant finning-upward successions correspond to meandering rivers (facies association D). In contrast, interbedded sandstones and mudstones were subsequently deposited by low-energy ephemeral rivers (facies association E). Finally, the upper third of the De La Cuesta Formation corresponds to eolian sandstones (facies association F) and shallow water bodies deposits, including evaporites, limestones, and tuffs (facies association G) sedimented under semiarid to arid conditions with periods of explosive volcanism.A U–Pb age of 278.84 Ma was obtained from a tuff level at the uppermost part of the De La Cuesta Formation (facies association G). This age, together with one previously obtained of 311.89 ± 0.21 Ma corresponding to the base of the unit, indicate that the De La Cuesta Formation is Moscovian-Kungurian in age and that it was mostly deposited before the main phase of the Choiyoi magmatism, synchronically with the so-called Pre-Choiyoi magmatism. Furthermore, a rich palynological assemblage belonging to the Lueckisporites/Weylandites Biozone (LW), recovered from deposits of the facies association G, is equivalent to the Lueckisporites virkkiae (Lv) Biozone from the Paraná Basin (Brazil), pointing out a Kungurian age for these biostratigraphic units.The new radiometric age and the palynological taxa recovered from the top of the De La Cuesta Formation (facies association G) confirm a Kungurian age for this interval, establishing a key level for correlation between the sedimentation in the retroarc with the onset of the Choiyoi Volcanism in the magmatic arc.

Late Jurassic-Early Cretaceous palynostratigraphy and palaeoclimate in the Andigama Basin, Sri Lanka

Sri Lanka consists of only ten percent of sedimentary rocks, and high-grade metamorphic rocks underlie the rest. Most of these sedimentary terrains are post-Gondwanic and such formations help to understand the geological history of the island. We report the first record of an age diagnostic (Late Jurassic-Early Cretaceous) palynological assemblage of the sedimentary rocks in the Andigama Basin (borehole AND BH01) Sri Lanka. The study was undertaken to assess the palaeoenvironmental settings in this basin based on palynological and palynofacies investigations. A palynofloral study suggests luxuriant gymnospermous forests proliferation in the Andigama Basin during this time. The palynological assemblage is characterized by the predominance of coniferous pollen grains of Araucariacites spp., Callialasporites spp. along with some stratigraphically significant taxa viz., Cicatricosisporites spp., Aequitriradites verrucosus, Triporoletes sp., Impardecispora indica, Concavissimisporites verrucatus, Distaltriangulisporites perplexus, Verrucosisporites verrucosus, and Contignisporites fornicates of Tithonian-Berriasian time. Palynofacies records suggest three distinct Palynofacies Assemblages (PF 1–3). PF 1 indicates the forest swamp; PF 2 represents the mixed assemblage of forest swamp and reed marshes, while PF 3 suggests reed marshes/lakeshore deposits under oxic-anoxic environments. These palynofacies assemblage along with variable lithological counterparts varying from carbonaceous shale laminae interlayered with calcareous sandstone to brown shale and carbonaceous shale strata reflects diverse hydrodynamic conditions. Palynofloral and palynofacies records of the present study denote the warm and humid climatic conditions, which directly corroborates with global oxygen isotopic studies of the Late Jurassic-Early Cretaceous sediments.

Palynological Studies of Upper Creataceous-Paleocene Rocks in Auchi Sheet 266, Benin Flank, Western Extension of the Anambra Basin, Southwestern Nigeria

Out crop samples from Mamu and Nsuka Formation at different locations and ditch cutting samples gotten from a water borehole at Ugbekpe-Ekperi road at different intervals collected from Benin Flank, Western extension of the Anambra Basin, were used for sedimentologic and palynology studies with the aim of establishing palynological assemblage zones, age and paleoenvironments of the sediments. Out crops and Ditch cutting samples were lithologically described using a transmitted light microscope in order to obtain their lithofacies and latter subjected to palynological slides preparation to identify the presence of palynomorphs. Lithofacies units identified were clay, sandy clay, silt, sandstone, shale and sandy shale facies. From the analyzed palynological slides, ninety one (91) palynomorphs species were identified in the outcrop samples, eighty three (83) were Miospores (pollen and spores) and seven (7) were Dinocysts while the borehole samples recorded fifty five (55) palynomorph species, forty three (43) were Miospores while fifteen (15) were Dinocyst. Clusters analysis were used to establish four (4) Palynological Assemblage zones which are Palynological Assemblage zones 1, 2, 3 and 4. Late Maastrichtian to Early Paleocene age is suggested for Nsukka Formation because of the presence / abundance of Spinizonocolpites baculatus with admixture of Apectodinium homomorphum and Homotryblium tenuispinosum. The occurrence of Monocolpites marginatus, Retidiporites magdalenensis, and non-occurrence of Spinizonocolpites baculatus in the outcrop samples suggests that Mamu Formation did not penetrate Late Maastrichtian. Thus Early to Middle Maastrichtian is suggested for Mamu formation. The occurrence of mangrove palynomorphs Zonocostites ramonae, fresh water algae Botryococcus braunii and Concentricyst circulus indicates sedimentation in coastal to shallow marine environment close to mangrove vegetation.