Mercedes di Pasquo

The palynology of the Lower Permian (Asselian-?Artinskian) Copacabana Formation of Apillapampa, Cochabamba, Bolivia

The palynostratigraphy of the lower and Coal members of the Copacabana Formation from Apillapampa, central Bolivia was investigated. Twelve samples yielded abundant and diverse, moderately well-preserved pollen and spores. One new spore species, Dictyotriletes cousmineri, is described and 52 species are recorded for the first time in Bolivia. Two species each of acritarchs and scolecodonts are also present. The lowermost assemblage yielded Vittatina and taxa such as Pakhapites ovatus and Marsupipollenites striatus, which are characteristic of the Asselian—Early Artinskian Vittatina costabilis Zone of the Paraná Basin, Brazil. The uppermost assemblage is defined by the appearance of several species of Lueckisporites, together with species of Vittatina, Lunatisporites, Pakhapites, Hamiapollenites, Corisaccites, Mabuitasaccites, Striomonosaccites, Striatoabieites, Striatopodocarpites and Weylandites. Abundant monolete and trilete spores with subordinate pollen grains are present in the Coal Member. Those species suggest correlation to the Middle Artinskian—Wuachiapingian Lueckisporites virkkiae Zone of the Paraná Basin. Highly variable associations of gymnosperms occur in the lower member whereas pteridophytes, sphenophylls and lycopods are dominant in the overlying Coal Member. These groups of plants characterised terrestrial landscapes along marine margins during the Early Cisuralian, and confirm the widespread distribution of the Glossopteris flora during the Permian in Gondwanaland. Preliminary radiometric data from interbedded tuffs suggest an Asselian—Sakmarian age for the marine Copacabana Formation and a Sakmarian—?Artinskian age for the overlying Coal Member. These new data are highly significant in terms of Permian correlations in central South America.

Global biostratigraphic comparison and correlation of an early Cisuralian palynoflora from Bolivia

This paper presents new data about Early Permian (Cisuralian) strata, palynostratigraphy and absolute dating from the Copacabana Formation in central Bolivia. Recent stratigraphic and palynologic data from marine and transitional rocks at Apillapampa refine the age of Cisuralian palynomorphs in South America. Twelve samples interbedded with five volcanic ashes (processed and productive) yielded 94 palynomorph species arranged in two informal palynoassemblages: the lower assemblage Vittatina costabilis corresponds to one sample near the base of the Copacabana Formation and the upper Lueckisporites virkkiae assemblage occurs in overlying marine and coal-bearing transitional intervals. Ages were also independently refined by a modern review of conodonts, fusulinids, along with those U–Pb radiometric ages (Isotope Dilution Thermal Ionization Mass Spectrometry [ID-TIMS] of zircon-bearing interbedded tuffs). These data suggest that the lower marine member of the Copacabana Formation at this location is Asselian and Sakmarian. Lueckisporites virkkiae is a key species of palynomorph utilised in South American and global Permian biostratigraphic reconstructions. Hence, a thorough global comparison of these palynofloras and correlations is addressed in this contribution, considering first appearances of mainly cosmopolitan diagnostic taxa. Correlations are established with many similar Permian palynofloras, some also constrained with radiometric data, in South America (Brazil, Uruguay and Argentina) and elsewhere.

Integrated study of fauna and microflora from the Early Devonian (Pragian–Emsian) of northwestern Argentina

The Devonian System in northern Argentina has been broadly analysed, but details of its lithologies, biostratigraphy and fossil content have not been presented in a comprehensive study. We performed the first integrative analysis of the palynological and macrofossil content from the Pescado Formation at the Zenta Range, Argentina. We define a new species of cryptospore and extend the stratigraphic record of the ichnogenus Psammichnites isp. for South America. The stratigraphic ranges of the palynomorphs suggest a time span from the ?late Lochkovian to Pragian–earliest Emsian, but the co-occurrences of key invertebrates narrow the age of the beds to the late Pragian and early Emsian. Moreover, sedimentary analysis indicates a proximal shoreface–foreshore depocenter during this time range for the Zenta region. The contraction phase of the basin during the middle Pragian and Emsian is evidenced by the presence of sand bodies at the top of the column and the higher supply of terrigenous components. During this regression event, a low diversity Malvinokaffric Realm brachiopod assemblage occurs, with dominance of Australospirifer hawkinsi. The predominance of the latter species during this event is coeval with the first decline of the Malvinokaffric Realm in the neighbouring Paraná basin.

The occurrence of Potamomyces palmarensis sp. nov. in the Late Holocene of El Palmar National Park (Colón, Entre Ríos, Argentina) and transfer of fossil species of Mediaverrunites to Potamomyces

ABSTRACT We present the first record of Potamomyces Hyde (Ascomycota, Dothideomycetidae) from soil sediments of the El Palmar National Park, Entre Ríos, Argentina. Nineteen samples were taken (each 2–4 cm from the surface) of a 80 cm thick core composed of a homogeneous lithology of argillaceous fine-grained sands. This taxon was only identified in the basal sample of the core (371 ± 30 years BP), located in a palm area (Butia yatay) with a semi-dense herbaceous-shrub layer. We propose an amendment of the generic diagnosis based on the revision of the species described up to now, and of a new one here defined (P. palmarensis). Additionally, we confirm that the morphotaxon Mediaverrunites Jarzen & Elsik ex Nandi & A. Sinha is its junior synonym, so we propose new combinations for seven species. We recommend the use of this natural taxon instead of the morphotaxon in future contributions. In terms of the geographical and stratigraphical distribution of Potamomyces, our record is the first mentioned for Argentina and the southernmost for South America. Based on its ecological requirements, a humid sub-tropical environment and abundant organic matter in the soil are suggested for the Latest Holocene of the study region. This hypothesis is supported by current knowledge of regional climatic and environmental conditions for the study area during the short humid interval of the Little Ice Age.

Airborne fungal richness: proxies for floral composition and local climate in three sites at the El Palmar National Park (Colón, Entre Ríos, Argentina)

The analysis of the content of the airborne mycofloras from three Tauber traps (monthly from March 2011 to March 2013) located at a dense palm (EP3), a grassland (EP2) and a mixed area (EP1, composed of grassland, palms and wetland communities) was carried out. Their affinity with the floral composition of each site and a possible influence of local atmospheric conditions on total fungal spore richness were tested. This analysis allowed the recognition of 82 fungal morphotypes as a whole. The cluster analysis (Jaccard index) showed that EP1 and EP3 are similar communities and separated from the EP2 community (with a similarity index <52xa0%). The principal component analysis showed a positive correlation between the affinities of fungi substrates preferences and the floral physiognomy and composition in EP1 and EP3, whereas the EP2 area revealed a community of fungal taxa typical of grassland environments. Three peaks of species richness per year were registered: (1) from January to April (summer to beginning of autumn), (2) in July (winter) and (3) from October to November (spring) each year. In this exploratory research these peaks are related to warmer and rainy conditions during summer and spring and of maximum accumulation of organic matter during the winter. In summary, aeromycoflora communities could be used as ecological proxies to infer the main floral composition of a study site and as indicative of the climate regime of the area.

Palynologic delineation of the Devonian–Carboniferous boundary, West-Central Montana, USA

ABSTRACT Cratonic depositional systems in the Central Montana Trough involve the Devonian--Carboniferous boundary (DCB), and reflect both subtle regional epeirogeny and significant global glacioeustatic controls. A palynologic analysis of the upper Three Forks, Sappington and lower Lodgepole formations was carried out at the classic Logan Gulch location in Horseshoe Hills. The lower Trident Member of Three Forks Formation yielded low-diversity cosmopolitan, long ranging phytoplankton and few spores species (LAs1), attributed to the middle Famennian. The upper part of the same green seaway shale yielded only leiosphaerids and Botryococcus (LAs2), along with an external mold of a clymenid ammonoid. Age-diagnostic spores Retispora lepidophyta, Verrucosisporites nitidus and Vallatisporites vallatus from middle Sappington siltstone (LAs3) indicated a Strunian LN Zone. Two more assemblages from upper Cottonwood Canyon Member (LAs4) and false Bakken (LAs5), in the lower Lodgepole Formation yielded scarce, poorly preserved spores. The presence of Waltzispora polita in LAs4 indicated a Tournaisan-Visean age.

Late Pennsylvanian and Early Cisuralian palynofloras from the Rajmahal Basin, eastern India, and their chronological significance

ABSTRACT This work documents for the first time a palynological assemblage in the Rajmahal Basin, tentatively considered probable youngest Late Pennsylvanian assemblage, which was hitherto considered early Permian. The palynocomposition consists of 39 species (5 spores, 25 monosaccate, 5 bisaccate- 3 non striate and 2 striate grains, scarce Navifusa sp., scolecodont, algae and fungal hyphae). Two assemblages are described based on the first appearance of taxa, Assemblage I (608.90–599.00 m) dominated by monosaccates and absence of bisaccates and spores. Assemblage II (592.0–590.80 m) also dominated by monosaccates but with the inception of spores, bisaccates and marine palynomorphs. The Assemblage I is correlated to the oldest Potonieisporites neglectus Assemblage Zone of Tiwari and Tripathi based on their similarities and the absence of species recorded in the Assemblage II which is correlated to their overlying Plicatipollenites gondwanensis Assemblage Zone. Palynoassemblages similar to the Assemblage I, radiometrically constrained to the Late Pennsylvanian across Gondwana, along with the lack of diagnostic Permian pollen grains as well as marine Eurydesma fauna and terrestrial glossopterids, tentatively support an older age at least for the lower interval of the Talchir Formation. The latter fossils associated to Assemblage II confirm an early Permian age.