First evidence of Devonian strata in Sweden - A palynological investigation of Ovedskloster drillcores 1 and 2, Skane, Sweden

Palynological analyses were carried out on 50 samples from the Övedskloster 1 (Ö1) and 2 drillcores (Ö2), southern Sweden. The study revealed well-preserved palynological assemblages including 77 spore species in 28 genera, and some additional forms retained under open nomenclature. The spore assemblages are collectively dominated by trilete spores in terms of abundance and diversity and have been ascribed to two informal palynozones (Assemblage A and Assemblage B), based on the representation of spore taxa. The presence of the spore species Acinosporites salopiensis, Chelinohilates erraticus, Cymbohilates allenii, Cymbohilates allenii var. magnus, and Retusotriletes maccullockii indicates that the stratigraphic succession spans the Silurian–Devonian boundary (Přídolí–Lochkovian), and thus constitutes the first robust evidence of Devonian strata on the Swedish mainland. These results have implications for the age of fossil faunas (e.g. fish) from the same deposits, previously dated as late Silurian. Palynofacies analyses reveal a shallowing-upward succession with nearshore marine marls at the base of the investigated core, grading into sandstones in conjunction with a decrease in the relative abundance of marine palynomorphs. The uppermost 70 m are mainly represented by red sandstones that are devoid of recognizable palynomorphs and host only phytodebris. We interpret this interval to represent predominantly paralic to fluvial deposits equivalent to facies represented in the Old Red Sandstone of Britain

Late Ordovician (Katian) spores in Sweden: oldest land plant remains from Baltica

A palynological study of the Ordovician–Silurian boundary (Katian–Rhuddanian) succession in the Röstaånga-1 drillcore, southern Sweden, has been performed. The lithology is dominated by mudstone and graptolitic shale, with subordinate limestone, formed in the deeper marine halo of southernBaltica. The palynological assemblages are dominated by marine microfossils, mainly chitinozoans and acritarchs. Sparse but well-preserved cryptospores, including Tetrahedraletes medinensis, Tetrahedraletes grayii and Pseudodyadospora sp., were encountered in the Lindegård Formation (late Katian–early Hirnantian), with the oldest record just above the first appearance of the graptolite species Dicellograptus complanatus. This represents the earliest record of early land plant spores from Sweden and possibly also from Baltica and implies that land plants had migrated to the palaeocontinent Baltica by at least the Late Ordovician

Baltica cradle of early land plants? Oldest record of trilete spores and diversecryptospore assemblages; evidence from Ordovician successions of Sweden

The origin of land plants is one of the most important evolutionary events in Earth’s history. The mode and timing of the terrestrialization of plants remains debated and previous data indicate Gondwana to be the center of land-plant radiation at ~ 470–460 Ma. Here we present the oldest occurrences of trilete spores, probably the earliest traces of vascular land plants yet recorded. The spores occur in Ordovician, Sandbian (455 million years old) successions in central Sweden, once part of the paleocontinent Baltica. These strata are independently dated by marine microfossils (conodonts) and 206Pb/238U dating of volcanic ash deposits. Our discovery extends the record of trilete spores globally by ~8 million years, and for Baltica by ~25 million years. Additionally, cryptospore assemblages are identified revealing a diverse and stable mid-Ordovician (Darriwilian: ~ 460 Ma) vegetation of free-sporing plants. The formation of regolith substrates on land as a consequence of permanent plant cover must in turn have affected the marine biota. We link these early land plant spore occurrences to the extensive, nutrient-rich volcanic ash deposits and propose Baltica as the possible original region of the radiation of early land plants.Financial support was also provided by Fondo para la Investigación Científica y Tecnológica (FONCYT), PICT 2017-0532 to C. Rubinstein, and by the Swedish Research Council (VR) through Lund University Carbon Cycle Centre (LUCCI) to V. Vajda.</p

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 (&gt; 20 km) of post mid- Devonian strata and is one of the main hydrocarbonproducing 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.The authors acknowledge the Karazin Kharkiv National University, the host organisation of the 100th anniversary of V.P. Makrydin during which the samples were collected. This is a contribution to the UNESCO/IGCP project 632, Continental Crises of the Jurassic: Major Extinction Events and Environmental Changes Within Lacustrine Ecosystems. The authors further acknowledge the support of the Swedish Research Council (Research links, 2013-6702), for O.S. and V.V. and that of Lund University Carbon Centre (LUCCI) for S.S. and V.V.</p

Palynostratigraphy of dinosaur footprint-bearing deposits from theTriassic–Jurassic boundary interval of Sweden

The Triassic–Jurassic boundary (c. 200 Ma) marks one of the five largest Phanerozoic mass extinction events and is characterized by a major turnover in biotas. A palynological study of sedimentary rock slabs bearing dinosaur footprints from Rhaeto–Hettangian strata of Skåne, Sweden was carried out. The theropod dinosaur footprints (Kayentapus soltykovensis) derive from the southern part of the abandoned Vallåkra quarry (Höganäs Formation) and were originally dated as earliest Jurassic (Hettangian) based on lithostratigraphy. Our results reveal that two of the footprints are correlative with the latest Triassic (latest Rhaetian) disaster zone typified by a high abundance of the enigmatic gymnosperm pollen Ricciisporites tuberculatus and Perinopollenites elatoides together with the key taxon Limbosporites lundbladii and fern spores. Two footprints are dated to correlate with the Transitional Spore-spike Interval. One footprint is interpreted as Hettangian in age based on the relatively high abundance of Pinuspollenites spp. together with the presence of the key taxa Retitriletes semimuris and Zebrasporites intercriptus. Our new palynological study suggests that the Kayentapus ichnogenus already appeared in the end of Triassic, and our study highlights the use of palynology as a powerful tool to date historical collections of fossils in museums, universities and elsewhere. The Hettangian footprint reflects a marine influence while all other studied ichnofossil specimens occur in non-marine (floodplain and delta interdistributary) sediments. The sediments associated with the Hettangian footprint include a significant proportion of charcoal transported from land after wildfires. The Rhaeto–Hettangian vegetation was otherwise characterized by multi-storey gymnosperm–pteridophyte communities