Publication Date:
2023-07-10
Description:
Tropical climates reached their northernmost expansion during the early Paleogene greenhouse phase, supporting a paratropical biota as far north as the southern shore of the ancient North Sea. There, relative sea-level fluctuations led to the formation of transgressive-regressive sequences, exposed in open-cast lignite mines in the area of Helmstedt (Lower Saxony, Germany), which record environmental changes at the marine-terrestrial interface. We studied an example from the middle Eocene of the Helmstedt Mine from which we reconstruct ecological successions from open estuary to meandering river environments, which represent vegetation at the Paleogene climatic optimum. In the absence of vertebrate and shelly fossils, environmental interpretations are made exclusively on plant matter in the sediment. Vegetational reconstructions are based mainly on quantitative palynological analyses, supported by paleobotanical and organic-petrographical evidence and confirmed by Principal Component Analysis. Diverse dinocyst assemblages in conjunction with Ophiomorpha-type bioturbation indicate open estuarine conditions. These are succeeded by mangrove, represented by pollen of Rhizophora, Avicennia, Nypa and the form species Psilodiporites iszkaszentgoergyi, and marsh environments, indicated by pollen of Restionaceae, Sparganiaceae/Typhaceae and fern spores. Subsequent lowland mire forests are characterized by a dominance of either the Tricolporopollenites cingulum group (Fagaceae) or triporate pollen of the Triporopollenites robustus/rhenanus complex (Myricaceae/Betulaceae). Within this landscape coexists a meandering river system, represented by channel lag and point-bar deposits of the active channel and by the clastic to lignitic sedimentary fill of an abandoned channel.
Keywords:
Araliaceoipollenites spp.; Arecipites sp.; Baculatisporites sp.; Basopollis orthobasalis; Bombacacidites sp.; Botryococcus; Brevaxones undifferentiated; Brosipollis salebrosus; Camarozonosporites sp.; Caryapollenites triangulus; Celtipollenites spp.; Cicatricosisporites sp.; Compositoipollenites rhizophorus; Dicolpopollis kockeli; Dinoflagellate cyst; Droseridites sp.; Emmapollis pseudoemmaensis; Ericipites spp.; Helmstedt; Ilexpollenites spp.; Inaperturopollenites sp.; Intratriporopollenites maxoides; Labraferoidaepollenites menatensis; Labrapollis labraferus; Laevigatosporites sp.; Leiotriletes sp.; Lithology/composition/facies; Lower Saxony, Northern Germany; Milfordia minima; Momipites punctatus; Momipites quietus; Monocolpopollenites tranquillus; Nepenthes-type; Nudopollis terminalis; Nyssapollenites kruschi; ORDINAL NUMBER; OUTCROP; Outcrop sample; Ovoidites sp.; Pentapollenites pentangulus; Pityosporites labdacus; Planctonites stellarius; Platycaryapollenites spp.; Plicapollis pseudoexcelsus; Plicatopollis plicatus; Pollen, tricolporate undifferentiated; pollen analytical standard techniques (Faegri & Iversen, 1989, Textbook Pollen); Polypodiaceoisporites sp.; Polyporopollenites spp.; Pompeckjoidaepollenites subhercynicus; Porocolpopollenites rarobaculatus; Porocolpopollenites sp.; Prasinophytes; Psilodiporites iszkaszentgyoergyi; Pterocaryapollenites stellatus; Punctilongisulcites microechinatus; Reticulataepollis intergranulatus; Sparganiaceaepollenites sp.; Spinaepollis spinosus; Spinizonocolpites spp.; Spores, trilete undifferentiated; Stereisporites sp.; Subtriporopollenites anulatus; Subtriporopollenites constans; sum spores; Tegumentisporis sp.; Tetracolporopollenites spp.; Thomsonipollis magnificus; Triatriopollenites bituitus; Triatriopollenites excelsus; Triatriopollenites rurensis; Tricolpopollenites asper; Tricolpopollenites liblarensis; Tricolpopollenites microhenrici; Tricolpopollenites quisqualis; Tricolpopollenites retiformis; Tricolpopollenites vegetus; Tricolporopollenites cingulum; Tricolporopollenites crassiexinus; Tricolporopollenites edmundii; Tricolporopollenites eofagoides; Tricolporopollenites mansfeldensis; Tricolporopollenites marcodurensis; Tricolporopollenites megaexactus; Tricolporopollenites messelensis; Tricolporopollenites microporitus; Tricolporopollenites microreticulatus; Tricolporopollenites parmularius; Tricolporopollenites pseudocingulum; Tricolporopollenites satzveyensis; Tricolporopollenites sole de portai; Tricolporopollenites sp.; Tricolporopollenites vancampoae; Triporopollenites coryloides; Triporopollenites rhenanus; Triporopollenites robustus; Varia; Verrucatosporites favus; Zonocostites ramonae
Type:
Dataset
Format:
text/tab-separated-values, 2820 data points
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