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New evidence from taxonomically rich and age-diagnostic acritarch assemblages is used to recognize Upper Cambrian and Tremadoc strata in the Bugrino 1 and North-Western 202 boreholes on Kolguev Island, Arctic Russia. The position of the boundary between the Cambrian and Ordovician systems in the sedimentologically continuous successions is inferred, as are stratigraphic intervals equivalent to the Late Cambrian Peltura and Acerocare trilobite zones of Baltica. This is the first paleontological documentation of Cambrian strata on the island and, on a regional scale, within the Pechora Basin and northeastern Europe. The newly established biostratigraphy provides the maximum relative age for the basal portion of the sedimentary cover overlying the Timanian angular unconformity, which separates the sediments from deformed and metamorphosed basement. In turn, it constrains the time-span of the hiatus as pre- Late Cambrian and thus is significant for reconstructing the timing of the major tectonic events in this region of the Baltica palaeocontinent. Twenty-seven acritarch species are described in detail and 10 taxa are left under open nomenclature. The taxonomic attribution of several species is revised. The diagnosis of the genus Acanthodiacrodium is restricted, and those of Dasydiacrodium and Polygonium are emended. New combinations are proposed for the species Actinotodissus crinitus, A. formosus and Solisphaeridiumakrochordum, and new emendations and combinations for Actinotodissus polimorphus, A. secundarius, and A. spinutisus. A new species, Solisphaeridium chinese, is recognized. The stratigraphic ranges of taxa are compiled from global records and extension of some species ranges is suggested.
Reworking of Devonian, Carboniferous and Permian palynomorphs into the Lower Triassic of western Canada, Yukon, the Canadian Arctic Archipelago and Alaska has been documented by a number of workers. The phenomenon occurs in other northern circumpolar localities, such as East Greenland and the Barents Sea, and was probably widespread. Examples are given from western and eastern Europe, Russia, the Middle East, Pakistan, China, Brazil and Australia.
The abundance and diversity of reworked palynomorphs from a number of stratigraphic units of different ages into the Lower Triassic is an important palynostratigraphic phenomenon of chronostratigraphic value. It may be the result of a major regional regression in the late Permian, followed by a widespread marine transgression in the Early Triassic, or it may be due to tectonic activity resulting in eustatic sea-level rise. Whatever the mechanism, the advancing transgression resulted in erosion of exposed Devonian, Carboniferous and Permian rocks, but by Mid-Triassic times most pre-Triassic rocks had been covered by sediment, and the supply of reworked material much reduced.
Reworked Devonian taxa belong to a variety of suprageneric groups including cavate trilete spores (lycopsids), acavate trilete spores (ferns) and monolete spores; Lower Carboniferous taxa include cingulate trilete spores. Possibly reworked Upper Carboniferous and Permian pollen includes that of Gymnosperms—Cordaites, conifers, pteridosperms (taeniate bisaccate and polyplicates), and cycads and gnetophytes. Lower Triassic palynomorphs, possibly in situ, may include (sometimes abundant) acanthomorph acritarchs such as Micrhystridium breve, M. setasessitante, M. fragile and Wilsonastrum colonicum.
Lack of recognition of reworking has many implications concerning chronostratigraphy, palynostratigraphy, paleoenvironments, paleoclimates, coal petrography, thermal maturity, geochemistry, and chemostratigraphy. For example, if the Upper Permian and Lower Triassic Densoisporites playfordii, D. complicatus, D. nejburgii, Lundbladispora obsoleta and Aculeisporites variabilis are not in situ, but reworked specimens of the Devonian progymnosperm cavate morphon Geminospora lemurata, one has to question the commonly held view that a lycopsid dominated macroflora, with a large biomass, re-colonised the land in the Early Triassic. Lower Triassic assemblages in which reworking occurred but has not been recognised may give the impression of palynofloral diversity, whereas low diversity and low abundance would be more consistent with the hostile arid environment of the Lower Triassic. One Upper Permian and Lower Triassic plant entity, well-adapted to harsh conditions, was the algal cyst Chordecystia chalasta. Nevertheless, some higher plants must have survived the Permian–Triassic crisis as witnessed by the presence of gymnosperm pollen in the Mesozoic. This is Geological Survey of Canada (Calgary), Contribution no. 2004237.
The palynological assemblage of coal-bearing Upper Permian sequence of Talcher Coalfield registers presence of some peculiar organic remains. These are described as Orissiella gen. nov., which is characterized by a vesicle with collar-like structure at the oral end, spines and or corrugations on the body. The affinity and palaeoecological significance of Orissiella is also discussed.
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.
The 10.5 m deep “D-Dor” core was taken at Dor (Tantura Lagoon), on the Carmel coastal plain, Israel. The established chrono-stratigraphic sequence (based on x-ray radiographs, and both luminescence and radiocarbon dating) covers the last about 26,000 years. It provides the paleoenvironmental framework for the transition from hunter–gathering to agriculture in the Levant. Three clay units were identified, overlying kurkar (calcareous sandstone) and covered by 6.3 m of sand. The bottom clay unit is a paleosol. Pollen was not preserved in this unit. Gray clay (the top of which was dated to about 12,000 cal. YBP) was deposited, overlying the paleosol, in a wetland environment. Pollen was preserved only in the upper part of this unit. It indicates a slightly drier climate than today's, probably correlative with the Younger Dryas. At the beginning of the Holocene, between 10,300 and 9,550 cal. YBP, a new marsh originated, depositing dark clay. High concentrations of well-preserved pollen allowed the reconstruction of several fluctuations in humidity. When the marsh was first formed, precipitation was higher than today, and oak maquis was more extensive in the area. The date of the earliest submerged Pre-Pottery Neolithic settlement embedded in its upper part indicates that the marsh dried out no later than 9,400–8,550 cal. YBP. Around 5,000 years ago, long after the Early Holocene marsh had dried up, sand began to accumulate in the region as a consequence of the Holocene sea level rise, covering several submerged Neolithic settlements off the Carmel coast.
One hundred seventy-five samples from the Borden Delta provided a detailed biostratigraphic framework for part of the Lower Mississippian clastic succession in Kentucky and Indiana. The samples indicate the eastern and southern parts of the Borden Delta are correlative with the PC Biozone and CM Biozones of Western Europe respectively; however, biostratigraphical problems arise in the western part of the investigated area (Indiana). The appearance of Lycospora pusilla in the samples from south-central Indiana is important in that it raises questions regarding the level of the Tournaisian–Visean boundary, it suggests floral provincialism in this part of North America during the Lower Mississippian, and it does not correlate with the previously established miospore zone from Western Europe.
An illustrated, descriptive atlas of pollen and spores from wetland plants of the Florida Everglades was compiled to facilitate identification of dispersed palynomorphs in sediments. The atlas includes 121 wetland species characteristic of eleven plant associations of the Florida Everglades including sloughs, sawgrass marshes, tree islands, wet prairies, cypress domes, mangrove forests, salt marshes, sawgrass ridges, beach/dune communities, pine flatwoods/dry prairies, and disturbed/developed sites. We include light micrographs and detailed descriptions of 121 species, 110 genera, and 63 families.