Palynological Associations Research Articles

Palinologia da Formação Piauí, Pensilvaniano da bacia do Parnaíba: biocronoestratigrafia de intervalo selecionado do poço 1-UN-09-Pi (Caxias, MA, Brasil)

PALYNOLOGY OF THE PIAUI FORMATION, PENNSYLVANIAN OF THE PARNAIBA BASIN: BIOCHRONOSTRATIGRAPHY OF A SELECTED INTERVAL WITHIN THE BOREHOLE 1-UN-09-PI (CAXIAS, MA, BRAZIL). The Pennsylvanian Piaui Formation, basal unit of the Balsas Group, is constituted by sandstones, shales and limestones, with scarce palynological records. This unit is interpreted mainly as continental to shorefacies in origin. This paper presents the palynostratigraphical results obtained for the interval between 110.60 m and 178.12 m of the borehole 1-UN-09-PI, located in Caxias, Maranhao State, which corresponds to the upper microclastic portion of this unit in the borehole. Most part of the twelve core samples studied furnished palynological associations. Among the continental palynomorphs, saccate pollen grains are dominant, mainly taeniate bisaccate and non tateniate monosaccate species. Taking into account that there is no available palynological zonation of the Pennsylvanian-Permian interval of this basin, the scheme erected for the neighboring Amazonas Basin was used for comparisons. The records of certain species from spores and pollen, such as Raistrickia cephalata Playford & Dino, Protohaploxypinus amplus (Balme & Hennelly) Hart, Lunatisporites onerosus Playford & Dino, Verticipollenites sp., Striatopodocarpites sp. and Meristocorpus explicatus Playford & Dino, allow the correlation of most of the studied interval with the Raistrickia cephalata Zone, which was recognized for the middle portion of the Nova Olinda Formation (Amazonas Basin), regarded as Pennsylvanian (Moscovian) in age.

Primer registro de palinomorfos de edad pérmica en la Formación Río Francia (Paleozoico Superior, San Juan, Argentina)

First record of Permian age palynomorphs in the Rio Francia Formation (Upper Paleozoic, San Juan, Argentina). The palynological content of the middle and upper section of the Rio Francia Formation (Paganzo Basin) is here presented. Two palynological associations referable to DM Biozone (Raistrickia densa-Convolutispora muriornata), dominated by trilete spores and scarce monosaccate pollen grains, were obtained from carbonaceous levels of the middle section of the unit. An association dominated by the bisaccate, monosaccate, striated pollen grains and scarce trilete spores, that between their components outstand the presence of Vittatina costabilis Wilson emend. Tschudy & Kosanke, V. subsaccata Samoilovich emend. Jansonius, V. minima Jansonius, Striatopodocarpites cancellatus (Balme & Hennelly) Hart, S. phaleratus (Balme & Hennelly) Hart, Kraeuselisporites punctatus Jansonius, Barakarites rotatus (Balme & Hennelly) Bhardwaj & Tiwari, Tuberisaccites varius Lele & Makada, Polarisaccites bilaterales Ybert & Marques-Toigo, and regularly preserved grains referable to the genera Lueckisporites, Weylandites, Klausipollenites and Minutosaccus; belong to carbonaceous shales of the upper part of the formation; that would allow to suggest a Cisuralian-Guadalupian age for this association, equivalent to LW Biozone (Lueckisporites-Weylandites), more likely. Rio Francia Formation age is considered, from it palynological content, Pennsylvanian-Cisuralian/Guadalupian.

Palynological correlation of Carnian humid pulses throughout western Tethys

The Carnian Pluvial Event is an Upper Triassic swing toward increased rainfall best documented in the Tethys tropical belt, and mainly recognized on its effects on sedimentary systems, as the demise of carbonate platforms and the enhanced siliciclastic supply. In some portions of western Tethys, and particularly in the Raibler Schichten of the Northern Calcareous Alps and in the Dolomites, the Carnian Pluvial Event is recorded by four discrete siliciclastic pulses. In the Raibler Schichten, three siliciclastic intervals are documented and take the name of first, second and third shale. In order to correlate these pulses at the basinal scale, the study of the palynological assemblages in a section of the Raibler Schichten near Rubland (Austria), and of the classical succession of the Lunz nappe, have been carried out. More than eighty palynomorph species are recorded. Most of them correspond to typical Carnian morphospecies of the Carnian Pluvial Event in Europe. On the base of their stratigraphic distribution, three different palynomorph assemblages are described: Aulisporites astigmosus assemblage, Lagenella martinii assemblage and Granuloperculatipollis rudis assemblage. A fourth, older assemblage is also informally defined. A palynostratigraphic correlation between the NCA, the Germanic Basin and the Dolomites has been obtained. The four siliciclastic pulses recognized in the Raibler Schichten and Lunz are also found in the Dolomites, and yield the same palynological associations. The base of the Schilfsandstein, that record the Carnian Pluvial Event in the Germanic Basin, is correlated to the second or third siliciclastic pulse (first or second shale of the Raibler Schichten). Siliciclastic pulses are thus correlated throughout western Tethys, and can thus be interpreted as short-lived humid climate wiggles within the Carnian Pluvial Event. A quantitative analysis of the Carnian successions of the NCA highlights a shift toward hygrophytic elements in the uppermost Julian, and an abrupt return to xerophytic associations in the lower Tuvalian. The palynological hygrophytic associations that characterize the Aulisporites astigmosus and Lagenella martinii assemblages are present in many other parts of Europe and Middle East, suggesting that the Carnian Pluvial Event determined a humid climate perturbation in a wide area of the northern hemisphere spanning from tropical to high latitudes.

A Danian subtropical lacustrine palynobiota from South America (Bororó Formation, San Jorge Basin, Patagonia - Argentina)

New results on a lacustrine Danian palynological association in extra-andean northern Patagonia (lower member of the Cerro Bororo Formation, San Jorge Basin, Chubut province, Argentina) are presented. This is a contribution to the largely unexplored field of Paleogene freshwater environments. The palynobiota includes representatives of the kingdoms Protoctista and Plantae. Twelve of the aquatic species are Protoctista. From the nine Chlorophyta form-species, four correspond to Botryococcaceae, one to Coelastraceae and four to Zygnemataceae (Gelasinicysta, Schizosporis, Ovoidites, and Pseudoschizaea). The remaining forms are dinoflagellate cysts (Peridinium and dinocyst indet.) and prasinophyceans (Leiosphaeridia). Plants are represented by spores and pollen of Bryophytes (Sphagnaceae and Ricciaceae), Pteridophytes (Salviniaceae), and Angiosperms (Arecaceae, Araceae and Sparganiaceae/Typhaceae, the latter representing macrophytes living in or near the swampy areas). Other palynomorph groups closely related with biotopes of permanent moisture are dominated by spores of the families Selaginellaceae, Lycopodiaceae, Cyatheaceae, Schizaeaceae, Polypodiaceae and Psilotaceae. The palynological assemblage reflects a freshwater lacustrine environment that developed in a marine coastal zone nearby brackish coastal swamps. Based on the composition of the palynoflora including palm pollen and other thermophilous taxa, humid, warm climatic conditions are inferred for the area of deposition.

First record of Early Devonian (Lochkovian) flora from the Santa Rosa Formation - Alarache, Southern Bolivia

New information on plants and palynomorphs from Angosto de Alarache, South Bolivia, is presented. The plant remains appear at the base of the section. Dichotomizing sterile forms are assigned to Hostinella sp. and scarce stems terminated in spherical structures are interpreted as indetermined sporangia. The palynological association 1 recovered from this level contains abundant phytodebris, trilete spores, few cryptospores, algae, very poorly preserved chitinozoans, and other elements (fungi, ?lichens). Trilete spores assignable to Apiculiretusispora sp., Punctatisporites sp. and Retusotriletes sp., are obtained from the maceration of some isolated sporangia. The dichotomous branching of the stems and the trilete spores recovered from the isolated sporangia support its tracheophyte affinity. The palynological assemblage 2, obtained three metres above, contains abundant phytodebris and more diverse palynomorphs. Two new species (Retusotriletes albarinii n. sp., Acinosporites macgregorii n. sp.) are described. Based on the presence of the trilete spores Dictyotriletes emsiensis (ALLEN) MCGREGOR, Retusotriletes maculatus MCGREGOR and CAMFIELD, Apiculiretusispora plicata (ALLEN) STREEL and the absence, mainly of Verrucosisporites polygonalis LANNINGER and Urochitina loboi VOLKHEIMER et al., we propose a Lochkovian age but restricted up to the Late not latest Lochkovian, and the correlation with the lower part of the Emsiensis Zone of the Amazon Basin and the MN Zone of Western Europe. The abundance of fragmented stems of varied size and parallel to bedding planes, along with the isolated sporangia in the plant assemblage suggests a short distance transportation under low energy conditions, probably from marginal palaeoenvironments to low energy marine settings.

Palynological biozones and radiometric data at the Carboniferous–Permian boundary in western Gondwana

Absolute radiometric data obtained recently in Upper Paleozoic basins of South America and Southern Africa are available to constrain the age of some palynological biozones defined in the Western Gondwana. Some dates obtained from Argentina coincide with southern Africa's and are useful to constrain the palynological associations. In this way, the Permian Argentinian Lueckisporites– Weylandites (LW) Biozone is compared with the Lueckisporites virkkiae Biozone of Brazil and Zone 3 of South Africa. On the other hand, the palynofloras from Dwyka (South Africa) are comparable with Argentinian and Brazilian associations recovered near the Carboniferous–Permian boundary. Tuffaceous intervals of the Dwyka Group in South Africa suggest the beginning of that sequence at 307 Ma reaching the 290 Ma at the top. The available palynological, paleoenvironmental and radiometric data from these three western Gondwanan areas are analyzed and compared.

Late Maastrichtian dinoflagellate cysts from the Cerro Butaló section, southern Mendoza province, Argentina

Abstract. The Late Cretaceous Atlantic transgression in southern South America is recorded in western Argentina in the upper part of the Malargüe Group. The Cerro Butaló section outcrops in the south of Mendoza Province and comprises sediments attributable to the Jagüel and Roca formations. Well-preserved palynological associations were recovered from this section. Only the marine associations – dinoflagellate cysts, acritarchs and green algae – are considered in this article. A Late Maastrichtian age is suggested for the Roca and Jagüel formations based on the presence of Deflandrea galeata and Disphaerogena carposphaeropsis in the lower part of the section and Glaphyrocysta perforata in the upper part of the section and the absence of any Danian cosmopolitan markers. Variations in dinoflagellate cyst species diversity throughout the section permit recognition of two intervals that are probably related to different palaeoenvironmental conditions connected with episodes of sea-level fluctuation.

Stratigraphical and palaeogeographical significance of the continental sedimentary transition across the Permian–Triassic boundary in Spain

The Permian–Triassic transition, a time of phenomenal palaeoenvironmental and palaeogeographical change, represents the largest episode of mass extinctions known to palaeontologists. This episode is, however, very poorly understood, and a lack of sediments and palaeontological data, particularly in the continental record, is a feature common to every basin. Despite compelling information on the continental Permian–Triassic boundary (PTB) emerging from recent efforts evaluating vertebrate evolution, fungal events and isotope curves, results are still insufficient to make any valuable correlations among continental basins and are even less appropriate for relating sediments of continental to those of marine origin. The present report discusses and attempts to locate the PTB in the basins of Iberia and Balearic Islands through an analysis of the palaeontological and sedimentary record across the Permian–Triassic transition. The aim of the paper is to contribute to our present knowledge of the palaeogeographical and stratigraphical significance of the Permian and Triassic continental units of Western Europe. The present-day Iberian Ranges, Catalonian Ranges and Balearic Islands hold the most complete Late Permian–Early Triassic sedimentary record in Iberia. This record consists of alluvial sediments, mainly of braided fluvial systems, corresponding to the “Saxonian” and Buntsandstein facies. All the units examined so far have been dated through palynological associations. The two “Saxonian” facies formations are of Thuringian age, although the lower one shows some palynological elements of Autunian affinities. The Buntsandstein units range from Thuringian to Anisian in age, there being no evidence up to now of the Scythian in Iberia. The exact position of the PTB in Iberia is up to now impossible to pinpoint with the precision of the marine series. Sedimentary characteristics and palynological data in the Iberian Ranges point that it lies at the sedimentary interval, 10 to 30 m thick, formed by the upper member of the La Hoz del Gallo Formation and the lowermost beds of the Cañizar Formation or its time equivalent the Prades and Eramprunyá units in the Catalonian Ranges and the Asá and B-1 in the Balearic Islands. We compare a normalized standard Late Permian–Middle Triassic column of the Iberian Ranges with standards from Western and Central Europe and the Southern Urals using recent Permian time scales. A palaeogeographic essay map of the Permian–Triassic transition is provided for the Iberian Plate. The plate was located in a northern subtropical position, 200–400 km from the westernmost Tethys coast, as part of the Central Pangean Mountain Range comprised of the Appalachian–Mauretanide–Variscan orogenic belts of estimated altitudes 2000–4000 m. Based on this palaeogeographic location, sedimentary characteristics and the main wind flows established for the Tethys, we can infer conditions of high precipitation dominated by monsoon and seasonal regimes with isolated semiarid areas for the Iberian Plate during the transition.

Environmental change across the Paleocene–Eocene transition from eastern New Zealand: A marine palynological approach

Recent improvements in the resolution and calibration of dinoflagellate cyst (dinocyst) bioevents across the Paleocene–Eocene (P–E) transition in New Zealand allow better understanding of the relation between dinocyst variations and environmental change in southern mid-high latitudes during this ‘greenhouse’ climate. Combining information from land spore/pollen assemblages with coeval dinocyst records allows evaluation of plant changes in a marine-based timeframe. Palynological associations at Tawanui and Moeraki-Hampden, eastern New Zealand, fluctuate across the P–E transition and ‘local palynological phases’ are recognized. The onset of major fluctuations in dinocyst assemblages coincide with the intense warmth and excess carbon of the Initial Eocene thermal maximum (IETM). Changes in sea surface temperature (SST) appear to have been the main environmental factor that affected dinoflagellates. Short-lived intervals of higher SSTs, suggested by a high relative abundance of the Apectodinium complex, are seen during the IETM and lower Eocene. Abundant cysts of probable heterotrophic dinoflagellates suggest surface waters remained relatively eutrophic for up to 0.5 Myr after the onset of the IETM, perhaps in response to enhanced terrigenous input related to changes in the character and pattern of continental weathering. In contrast to dinocysts, spore/pollen assemblages suggest plant communities remained rather stable across the P–E transition. Vegetation was dominated by a mesothermal conifer-dominated multistratal rainforest, and low-latitude Nypa mangroves were established by the uppermost Paleocene. Plants in this region show no clear response to the IETM and the predominant vegetation change may have occurred at least 1.5 Myr later, characterized by an increase in mesothermal–megathermal angiosperm plants.

The palynology of the Cenomanian‐Turonian (Cretaceous) boundary succession at Aksudere in Crimea, Ukraine

The Upper Cenomanian ‘black shales’ at Aksudere in Crimea contain a distinct palynological association dominated by prasinophyte phycomata, mainly leiospheres and tasmanitids, and peridinioid dinoflagellate cysts, mainly Trithyrodinium suspectum ukrainense subsp. nov. Prasinophyte dominated assemblages have not previously been reported from Cenomanian‐Turonian boundary organic rich deposits. Their presence confirms probable deposition under oxygen‐deficient bottom waters in this area.

Upper Triassic carbonate deposits of Seram (Indonesia): palaeogeographic and geodynamic implications

The Upper Triassic limestones of central and western and Seram, were deposited on an extensive carbonate platform, already identified in various localities all around the Banda Sea: Sinta Ridge, central–east Sulawesi, Buru, Misool and the Wombat Plateau (off NW Australia). The Triassic deposits are found in the parautochthonous, as well as in the allochthonous series of Seram; the facies of the two series are of Gondwanian–Australian type in the Parautochthonous and of Laurussian–Asian type in the Allochthonous. The Asinepe Limestone (=Manusela Formation), on which this study is based, has been considered as part of the allochthonous series. The Triassic reefal lithotypes can be divided into four main facies, as follows: (1) the boundstone facies forming the buildup cores; (2) the oncolitic grainstone-rudstone facies, indicating high energy conditions; (3) foraminiferal packstone-grainstone facies, characteristic of moderate to high energy conditions; and (4) the foraminiferal-megalodont mudstone facies, inferred to have accumulated in a quiet lagoonal environment. Forming the buildup cores of about 4 m long, 2 m high; they are separated by depressions filled with reef detrital sands; The Asinepe Limestone was deposited during the Late Triassic (Carnian–Norian to Rhaetian). This range is corroborated by foraminiferal and palynological data, and the coral framebuilders give evidence for a Norian–Rhaetian age. There is a some consensus that Seram and the Island of Buru, located west of Seram, belong to the same tectonic block (Seram-Buru Block). According to geochemical and geodynamic interpretations, the Seram-Buru Block is derived from Irian Jaya or from Papua New Guinea. The palynological results are consistent with reconstructions that place the Seram-Buru Block in a palaeogeographic zone distinct from that of Sulawesi, and therefore from the Kolonodale Block. For these reasons, it is here proposed that, during the Upper Triassic, the Seram-Buru Block and the Kolonodale Block were two separated entities, the former located in a more tropical position than the latter. In addition, the Seram palynological association shows a composite microflora of the warm Onslow and the cold Ipswich-types, suggesting that the Seram microcontinent moved progressively to the north and crossed the boundary between the temperate and the warm subequatorial belts at one point in the Late Triassic–Early Jurassic.

THE PALYNOLOGY OF THE CENOMANIAN-TURONIAN (CRETACEOUS) BOUNDARY SUCCESSION AT AKSUDERE IN CRIMEA, UKRAINE

The Upper Cenomanian ‘black shales’ at Aksudere in Crimea contain a distinct palynological association dominated by prasinophyte phycomata, mainly leiospheres and tasmanitids, and peridinioid dinoflagellate cysts, mainly Trithyrodinium suspectum ukrainense subsp. nov. Prasinophyte dominated assemblages have not previously been reported from Cenomanian–Turonian boundary organic rich deposits. Their presence confirms probable deposition under oxygen-deficient bottom waters in this area.

Depositional environment of Bagra Formation (Upper Triassic), Satpura Basin, India: a palynological approach

Bagra Formation is the youngest lithounit of non-marine Mahadeva Group in Satpura Basin. The recorded palynological assemblage from Bagra Formation contains prominence of fungal and algal remains. Palynomorphs of Denwa Formation such as Falcisporites, Satsangisaccite, Samaropollenites, Arcuatipollenites, Strialopodocarpites including Callialasporites, Cycadopites, Corollina (=Classopollis) simplex and Haradisporites are also represented in the Bagra Assemblage. The palynological assemblage (as a mixed flora) suggests a lateral continuity of the Denwa Formation with younger Bagra Formation, and the difference could be facies variations. The recovered palynological assemblage suggests a Rhaetian age of Upper Triassic to the Bagra Formation. The palynological associations indicate that Bagra Formation was deposited in lacustrine set up near shoreline under cool-temperate climate with derivation of palynomorphs from heavy rain forest upland areas.

Le bassin permien de Guardia Pisano (Sud-Ouest de la Sardaigne, Italie) : palynostratigraphie, paléophytogéographie, corrélations et âge radiométrique des produits volcaniques associés

The Permian section outcropping at Guardia Pisano (Sulcis area, SW Sardinia), comprises two successions, separated by an unconformity. The lower succession is composed of grey–black sandy shales, rich in plant remains and in sporomorphs, deposited in a fluvial-lacustrine to palustrine environment; followed by layers of rhyolithic lavas and volcanoclastites with silicified plant trunks. Most of the analysed samples yielded a profusion of pollen and spores in a very good state of preservation. Three associations were distinguished. The first one comprises mostly radial and bilateral monosaccate pollen grains and very few spores. This association is characterized by the presence of pollen grains of the genera Crucisaccites, Luberisaccites, Gondwanopollis and Lueckisporites, together with very abundant Potonieisporites and subordinate Florinites. The second association comprises mostly pollen grains of the genus Potonieisporites, represented by many species, together with Limitisporites, Costapollenites, Vittatina and others. Spores mainly represented by azonate trilete and monolete types are more frequent than in the previous association. These first two palynological associations reflect assemblages of meso-xerophilous plants growing in dryer environments, belonging to tropical and subtropical phytogeographic biomas. The third association, mainly composed of Sphenophyte spores, is autochthonous and corresponds to a swampy hygrophilous flora settled after the filling up of the basin. The age inferred by means of sporomorphs is early Asselian which is in good agreement with the mean radiometric age of the volcanic rocks obtained by the ‘SHRIMP’ and the lead-zircon evaporation methods (297 ± 5 Ma). The upper succession, is composed of grey to red sandstones and thin pelites deposited on an alluvial plain under very hot and humid climate; its Permian, post–Asselian age cannot be better constrained because of the scarcity of the fossil content.

Liptinite in coal and oil source rocks in northern Thailand

Palynological study of northern Thailand coal and oil deposits indicates a similar palynological association to that of the Borneo region. Coal petrographic studies of these deposits show variations in the liptinite macerals, especially alginite types. The oldest of these coal and oil deposits, which are of Late Oligocene to Early Miocene age, are dominated by Botryococcus sp. or Botryococcus-related algae. Thick-walled lamaginites and spores and pollen of temperate affinity, are found in some areas. By contrast, thin-walled lamaginite is dominant in late Middle Miocene time. Resinite, suberinite, and cutinite are dominant in forest swamp coal deposits whereas alginite, cutinite and lycopodium spores are dominant in lacustrine environments. Exsudatinite is common even at early levels of maturation. These liptinite macerals can be major sources of oil and gas.

New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe

The palynological associations of 16 Karoo samples, collected in the Mana Pools basin, Northern Zimbabwe, were studied, and four zonal assemblages can be recognized. Assemblage I (Kondo Pools Formation) is dominated by monosaccate pollen grains and diverse alete bisaccate pollen grains occur frequently. Important but rare marker genera include Limitisporites, Vittatina and Weylandites. These indicate a middle to late Early Permian age (e.g. Late Sakmarian to Early Artinskian). The palynological assemblage, derived from the Massive Sandstone Member, Angwa Sandstone Formation, is characterized by a small number of smooth and apiculate spores, but is lacking any age significant marker taxa. Assemblages II and III, both from the Alternations Member (Angwa Sandstone Formation), and Assemblage IV (Pebbly Arkose Formation) are dominated by alete bisaccate and multitaeniate pollen grains. The rare occurrence of Vittatina, Weylandites lucifer and Guttulapollenites hannonicus indicates a Late Permian to Early Triassic age for Assemblage II. Based on sedimentological data and literature, a preliminary age of Early Triassic (Induan) can be given. A range from latest Fassanian (Ladinian) to Lacian (Norian) for Assemblage III is indicated by the occurrence of Asseretospora gyrata, Cadargasporites senectus, Eucommiidites, Infernopollenites, Minutosaccus crenulatus, Retisulcites perforatus and Samaropollenites speciosus. Small amounts of Asseretospora gyrata, Cadargasporites senectus, Cycadopites, Microcachryidites and Minutosaccus crenulatus indicate a slightly larger age range for Assemblage IV (e.g. Carnien to Rhaetian).

Relations microfossiles organiques—paléoenvironnements: exemples de deux formations dévoniennes du Massif Armoricain et d'Aquitaine

In this study, bi- and multivariate analysis (CFA) have been used to interpret palynological residues recovered from the Devonian deposits of the Clairac Formation (northern Aquitaine) and the Saint-Céneré Formation (Armorican Massif). These analyses are based on a quantification of the abundance of the main groups of palynomorphs (scolecodonts, chitinozoans, acritarchs, spores, plant debris, Tasmanacea) present in the deposits. They allowed a differentiation of palynological associations characteristic of each palaeoenvironment in both studied formations. For the Saint-Céneré Formation, a palaeoenvironmental evolution from a shallow-marine near-shore environment, with limited land-derived input, to open-shelf conditions has been documented. On the other hand, the upper part of the Clairac Formation is characterised by a palaeoenvironmental evolution from a fairly distal and quiet shelf environment to shallow, shoaly and more agitated conditions.

Nuevos datos sobre la estratigrafía, paleontología y procedencia paleogeográfica del Triásico de las escamas del Corredor del Boyar (Cordillera Bética Occidental)

The Upper Triassic of the Boyar Corridor (External zones, Western Betic Cordillera) is constituted by a lower carbonate unit and an upper clayey-sandy unit. Both units provide Upper Carnian palynological associations. Besides, the lower unit contains associations of bivalves similar to those of the alpine «Raibler Schichten». These lithostratigraphic units were deposited in very shallow marine (subtidal) and coastal plain environments (peritidal in a broad sense), that constituted the internal areas of a marine shelf that evolved from mainly carbonatic to siliciclastic along the Uper Triassic. The Triassic of the Boyar Corridor is thinner than the typical Median Subbetic Upper Triassic, but it contains much less clays and evaporites and more carbonate marine intercalations than the former. This fact as well as its tectonic position along the contact between the Median Subbetic and the Penibetie, allow to locate it in the palaeogeographic transition between both domains.

PALINOLOGIA DE DEPÓSITOS RUDÁCEOS DA REGIÃO DE ITATIAIA, BACIA DE RESENDE – RJ

The Resende Basin is associated with rifting processes which characterize the Cenozoic geologic evolutionof southeastern Brazil. Some palynological information is available from alluvial plain deposits of itssedimentary fill, the Resende Formation. Other associated deposits, having questionable relationships withthis unit, have also been mentioned in the literature. One of these consists of rudaceous deposits of alluvialfans, in which the clasts are chiefly of alkaline rocks from the Itatiaia massif. These deposits, of controversedage, include silty-sand layers, very rich in organic matter, whose palynological potential motivated the researchreported here.The palynological association suggests an Oligocene age for the deposition of the organic matter. Froma paleoecological point of view, this deposition took place under stagnant conditions, in a tropical to subtropicalclimate.Geologically, these results reinforce the idea of a close genetic relationship between the rudaceousalluvial fan deposits and the alluvial plain sediments of the Resende Formation. It is proposed here the nameof Itatiaia Formation for the alluvial fan deposits.

Reworked pollen assemblages and the Eocene-Oligocene boundary in the Paleogene of the western external French Alps

A study of the palynological associations of various outcrops from the Eocene-Oligocene of the western area of the “Delphino-helvetique zone” has been carried out in the French Alps. The Le Vît section, near Castellane and the Le Clouet section near Barrême, both in the Southern Subalpine Ranges, and several outcrops in the Le Déserts syncline (Savoy) in the Northern Subalpine Ranges have been examined. All these sections clearly show taxa reworked from earlier Paleogene deposits. The first occurrence of the reworked material was found at different levels in the various sections. However, a tentative correlation highlights a coincidence between reworking, shown in all sections, and the Eo-Oligocene boundary.