Devonian-Carboniferous palynoflora
Description
Palynomorph assemblages and palynofacies analysis have been performed on several core samples from the Devonian–Carboniferous deposits identified in five wells located in the eastern part of the Moesian Platform. The investigated sections include, in ascending stratigraphic order, the Ţăndărei, Smirna, Călăraşi and Vlaşin formations. Based on stratigraphic distribution of key taxa identified (miospores, chitinozoans, acritarchs), seven biozone intervals (four for Devonian and three for Carboniferous) have been recognized. The oldest samples were dated as being part of the micrornatus-newportense (MN) – lower part of breconensis-zavallatus (BZ) interval zones (early Devonian), while the younger ones are assigned to the kosankei-varioreticulatus (KV) – nobilis-junior (NJ) interval zones (late Carboniferous). Palynofacies observations suggest a more distal depositional environment during the period between Lochkovian and Pragian times, followed by some proximal/fluvio-deltaic conditions in Emsian–early Eifelian (the top of Ţăndărei Formation). The upper Tournaisian to Serpukhovian sedimentary rocks of the Călăraşi and lower part of Vlaşin formations were deposited in inner neritic environments. Mud-dominated dysoxic/anoxic conditions prevailed in the Bashkirian, which were quickly succeeded by a deltaic deposition and oxidizing environments which persisted up to Moscovian. The lower Devonian terrestrial palynoflora is dominated by trilete spores which belong to the lowland vegetation of a non-forest mire palaeoecological group. The Carboniferous deposits yielded only terrestrial palynomorphs of various types of arborescent and herbaceous lycopsids and ferns, suggesting different habitats such as non-flooded wetlands or swamps within coastal plain and continental interiors. These assemblages of Carboniferous miospores are an indication of the neutral-humid climatic conditions which existed at the time of deposition.