The fossil megaflora of the Březno beds s.s. (fine-grained mudstone-dominated facies, as opposed to the coarse-grained facies of the so-called Chlomek or Chloumek beds, both constituting the Březno ...Formation s.l.) is investigated on the basis of 38 specimens, 31 of them coming from Březno. The other localities are Podlesí (Waldek or Valdek), Opatovice nad Labem, and Vršovice u Loun. The most common species are the conifers Frenelopsis cf. alata (9 specimens, 24% of the material) and Geinitzia reichenbachii (8 specimens, 21%). In the entire assemblage conifers are represented by five taxa (31% of the total) and 26 specimens (68% of the total). Angiosperms (10 taxa, 63% of the total) are mostly represented by single specimens.
Fertile material includes conifers Araucaria fricii (Araucariaceae) and Sphenolepis lepidota (Cupressaceae) as well as angiosperms Anthocephale bohemica (infrutescence incertae sedis) and Allericarpus parvivalvis (Bayer) J. Kvaček et Heřmanová (Ericales, fruit). The rest of the megaflora consists of leaves. The new form group Elattophylls Halamski represented in the material studied by Densinervum manifestum (Bayer) Halamski and J. Kvaček is proposed for leaves with low rank venation. Rubiaephyllum Bayer emend. J. Kvaček is emended as a fossil-genus for elliptic leaves with pinnate venation and an apical gland. The following new combinations are introduced: Sphenolepis lepidota (Bayer) J. Kvaček et Halamski comb. nov., Dicotylophyllum caloneurum (Bayer) Halamski and J. Kvaček comb. nov., and Densinervum manifestum (Bayer) Halamski and J. Kvaček comb. nov.
The microflora was investigated at Březno and is dominated by marine species (58%, 16 taxa). Among terrestrial palynomorphs (26 taxa) the Normapolles group is the richest with the most diversified genus Trudopollis (five species). The occurrence of Vitreisporites pallidus (Reissinger) Nilsson is the youngest record of the Caytoniales in Europe and is only slightly older than the youngest world record of this group of plants (Santonian of Sakhalin). The palynomorph assemblage allows the studied flora to be dated to the Coniacian.
•Mega- and microflora of the Březno beds (Coniacian, Czech Republic) is described.•16 megafloral fossil-taxa and 26 terrestrial and 16 marine palynomorphs are reported.•The most common plants are Frenelopsis (salty marshes) and Geinitzia (back swamps).•Form group Elattophylls Halamski is proposed for leaves with low rank venation.•Vitreisporites pallidus is the youngest record of the Caytoniales in Europe.
Magmatic-hydrothermal transition of highly evolved granitic melts enriched in volatile and incompatible elements can involve disequilibrium intermediate products between aluminosilicate melt and ...hydrothermal fluid (hydrosilicate liquids) with high ore-forming potential. We investigate evolution from Li-F-rich granites through pegmatites, greisens and quartz veins in a composite stock at Knöttel in the Krupka district (eastern Krušné hory/Erzgebirge mountain range) by monitoring trace-element variations in quartz. Interelemental correlations reveal Si4+ ↔ Li+Al3+ and likely Si4+ ↔ H+Al3+ to be the most important substitution mechanisms. Variations in Ti vs. Li, Be and Al define distinct evolutionary trends: (i) magmatic, high-Li/Ti or Al/Ti trend (granites – aplites – K-feldspar pegmatite); (ii) transitional, medium-Li/Ti trend (quartz megacrysts and pegmatite lenses in granite – quartz-protolithionite pegmatite); (iii) hydrothermal, low-Li/Ti or Al/Ti trend (stockwork of coarse-grained hydrothermal quartzites and quartz veins, quartz replacement in greisens). The medium-Li/Ti trend represents hydrosilicate liquid, an H2O- and SiO2-rich medium with low density and effective viscosity that was probably formed during disequilibrium crystallization in front of rapidly propagating solidification front. Thermal evolution of the magmatic-hydrothermal system was monitored by Ti-in-quartz thermometry. Calculated rutile activity of the granites is very low (0.3–0.05) but it increases (up to 1, that is, saturation) towards pegmatites and hydrothermal veins. Magmatic crystallization (granites and aplites) is constrained to 700–580 °C, pegmatite and bulk greisenization stage occurred at 600–500 °C, followed by a late hydrothermal stage associated with the formation of distal quartz veins at 500–390 °C. The granite-pegmatite systems at Knöttel and in Erzgebirge in general reach extremely high Al, Li, Rb and Ge and low Ti concentrations in quartz in comparison with igneous rocks worldwide. The Knöttel stock belongs to P-poor A-type granites in the Erzgebirge and is linked with them by similar evolutionary trends in quartz trace elements. Furthermore, the Knöttel system exhibits Be enrichment in quartz (probably related to high contents of F) and this appears to be typical feature of Mo-W-mineralized systems in general. The hydrothermal phase with Mo-W mineralization at Knöttel is closely related to the magmatic phase of parental granite body, which seems to be an important condition for Mo-W-mineralization formation.
•Unique sequence of granites, pegmatites, hydrothermal stockwork and veins reveals several trends of trace elements in quartz.•Extreme differentiation has been achieved by disequilibrium crystallization and propagation of solidification fronts in a composite magma reservoir.•Magmatic-hydrothermal transition is discontinuous, associated with large-scale silicification.•Be enrichment in quartz is a typical feature of Mo-W-mineralized silicic systems worldwide.
Upper Turonian to lower Coniacian marls of the Strehlen Formation of the Graupa 60/1 core were investigated for their foraminiferal content to add stratigraphical and palaeoenvironmental information ...about the transitional facies zone of the Saxonian Cretaceous Basin. Further comparison with foraminiferal faunas of the Brausnitzbach Marl (Schrammstein Formation) were carried out to clarify its relationship to the marls of the Graupa 60/1 core. Tethyan agglutinated marker species for the late Turonian to early Coniacian confirm the proposed age of the marls of the Graupa 60/1 core and the Brausnitzbach Marl. The palaeoenvironment of the marls reflects middle to outer shelf conditions. The maximum flooding zones of genetic sequences TUR6, TUR7 and CON1 could be linked to acmes of foraminiferal species and foraminiferal morphogroups. In general, a rise of the relative sea-level can be recognised from the base to the top of the marls of the Graupa 60/1 core. While agglutinated foraminiferal assemblages suggest a generally high organic matter influx and variable but high productivity in the Graupa 60/1 core, the Brausnitzbach Marl deposition was characterized by moderate productivity and a generally shallower water depth.
The proposed definition of the Turonian/Coniacian boundary, at the first occurrence of the inoceramid bivalve
Cremnoceramus deformis erectus (Meek) (=
Cremnoceramus rotundatus (
sensu Tröger
non ...Fiege)), prompted a rigorous study of the calcareous nannofossil events through this interval, both for calibration of the calcareous nannofossil biostratigraphy, and to provide an assessment of the suitability, in calcareous nannofossil terms, of the proposed stratotype section. New calcareous nannofossil data are presented here, detailing the biostratigraphy of the boundary interval from four locations. These include the candidate boundary-stratotype, the Salzgitter-Salder Quarry section (northern Germany), as well as the Slupia Nadbrzezna outcrop (central Poland), a potential secondary reference section. Also included is the Brezno Pd-1 Borehole and outcrops in the Brezno Formation (= Priesener Schichten) type-area (north-western Czech Republic), which represents an original boundary candidate (Copenhagen Stage Boundaries Meeting, 1983), and the Langdon Stairs coastal section (south-eastern England), part of the British Chalk succession. The calcareous nannofossil events derived from each section provide a sequence across the boundary of (in stratigraphical order): below the boundary, the first occurrence of
Lithastrinus septenarius followed by that of
Broinsonia parca expansa; above the boundary, the last occurrence of
Helicolithus turonicus followed by the first occurrence of
Micula staurophora (=
Micula decussata of some authors). This places the boundary within Nannofossil Subzone UC9c. A similar sequence of events has previously been determined from sections in north-eastern England and in the south-eastern Indian Ocean. The presented data and correlations suggest that either the Salzgitter-Salder Quarry section or the Slupia Nadbrzezna outcrop section would make a suitable Global Stratotype Section for the Turonian/Coniacian boundary, as far as calcareous nannofossils are concerned. The use of the calcareous nannofossil
Marthasterites furcatus, widely quoted as an indicator of this boundary, is discussed and proved to be untenable.
We present the interpretation of tectono-sedimentary evolution of the West Sudetic area (central Europe) during the latest Turonian–middle Coniacian as recorded by deposits of the NW part of the ...Bohemian Cretaceous Basin. This paper provides the first strontium isotope curve from the Upper Cretaceous of the Bohemian Massif. The exact stratigraphic framework was provided by combining of macrofossils (inoceramids) and calcareous nannofossils. Six inoceramid zones were distinguished, from Cremnoceramus deformis erectus Zone to Volviceramus koeneni Zone. Biostratigraphic data were combined with XRF curves and geophysical logs which allowed for correlation of several key sections within the study area. Using the genetic stratigraphy, contrasting parts of the depositional system interpreted as nearshore to deltaic were successfully correlated. Six elementary sequences were defined within the studied succession. These are TUR 7 (latest Turonian), backstepping, aggradation-dominated, with a short-term progradational episode and CON 1 to 5 (early–middle Coniacian), deposited during a period of increasing depth through time. The progradational pattern is most typical for the CON 4 sequence. Intensified sediment supply resulting in pronounced progradation is also evidenced by increased siliciclastic influx to the offshore zone and resulting changes in calcareous nannofossil assemblages.
Three major transgressive events are interpreted at the base of sequences: (1) CON 1 (close to the Turonian–Coniacian boundary); (2) CON 2 (near FO of Cremnoceramus crassus crassus); (3) CON 5. The transgressions were predominantly driven by basin-floor subsidence, although the transgression at the Turonian–Coniacian boundary and at the base of sequence CON 2 likely carried a component of eustatic sea-level rise. The accelerated basin-floor tectonic subsidence and source uplift in the NW part of BCB falls within the early Ilsede phase of the Late Cretaceous (‘Subhercynian’) deformation of the Alpine foreland.
•Integrated stratigraphic model of the Coniacian of NW Bohemian Cretaceous Basin.•The first 87Sr/86Sr isotope data from the Bohemian Cretaceous Basin.•Sedimentary record evidences changing tectonic regime during the Coniacian.
We have studied the petrography and the bulk-rock geochemistry of arenites and mudstones of the Cenomanian Peruc-Korycany Formation to characterize their provenance and sedimentary history, as well ...as the influence of weathering, hydraulic sorting, and recycling of the source rocks. The Peruc-Korycany Formation contains sedimentary facies reflecting both meandering- and braided-river systems and shallow-marine systems. Differences in the three depositional settings did not cause distinctly different modifications of the framework compositions of the arenites. The sand from the fluvial systems is very mature (Qm
98
F
0
Lt
2
). These fluvial arenites were subsequently modified by shallow-marine processes; reworking produced very slight decreases in the abundance of lithic fragments and polycrystalline quartz grains. The Cenomanian strata of the Bohemian Cretaceous Basin were derived dominantly from metasedimentary and crystalline rocks of the Palaeozoic Teplà-Barrandian and Cadomian Moldanubian units, respectively. Periods of low tectonic activity resulted in the deposition of arenites with quartzose framework compositions, indicating that climatic and/or transport/depositional-environmental controls overwhelmed factors such as source-rock compositions. Ultrastable dense minerals are useful indicators of sedimentary recycling within the Peruc-Korycanytarenites. Mudstone samples are characterized by abundant kaolinite, illite, chlorite, and quartz but by negligible amounts of goethite and gypsum. Concentrations normalized to the post-Archaean Australian shale (PAAS) show that the sediments are strongly depleted of Na, K, Ca, Sr, and Ba, probably because of the mobility of these elements during weathering. Chemical indices of alteration (CIA, CIW, and PIA) show that the degree of weathering of the source area was high. The data fall closer to the compositional fields of highly weathered minerals such as kaolinite, gibbsite, and chlorite on an A-CN-K diagram. The indices of compositional variability of the studied samples are much less than 1, suggesting that the samples are compositionally mature and were likely dominated by recycling. The elemental ratios critical of provenance (La/Sc, Th/Sc, Th/Co, Th/Cr, and Cr/Th) are similar to fine fractions derived from the weathering of mostly granitoids rather than mafic rocks.
Because of close morphological affinities, fossil cheliped fragments of the ghost shrimp
(Decapoda, Axiidea, Ctenochelidae) can be easily misidentified as remains of different decapod crustacean ...taxa. Re-examination of the Cretaceous decapods deposited in the National Museum in Prague revealed that all supposed specimens of the lobster genus
found in the Middle Coniacian calcareous claystones of the Březno Formation, including one of the Fritsch's original specimens of
, actually belong to
. This material together with newly collected specimens from the same locality, allowed for erection of a new species,
Its major chela possesses a serrated ischium and ovoid, unarmed merus; therefore, it is considered a close relative of the extant
and
.
sp. nov. represents the first report on the occurrence of the genus from the Bohemian Cretaceous Basin. It is one of the oldest records of
and simultaneously one of the best preserved fossils of the genus reported to date. Confusing taxonomy of
is reviewed and shortly discussed.
The first occurrence (FO) of Marthasterites furcatus was correlated with the FOs of other nannofossils, inoceramid bivalves and foraminifers in the Bohemian Cretaceous Basin and Outer Flysch ...Carpathians. The correlation showed that the FO of M. furcatus was diachronous, becoming younger from east to west. In the Silesian Unit it appears in the lower Turonian in association with Eprolithus moratus (UC6b nannofossil Zone). In the Pavlovské vrchy klippes it appears in the upper middle Turonian together with Lithastrinus septenarius (UC9 Zone). In the Bohemian Cretaceous Basin, the FO of M. furcatus was observed in the lower upper Turonian just above the FO of Liliasterites angularis. The presence of M. furcatus in Turonian strata is scarce and discontinuous up to its sudden quantitative increase (represented by 5–27% in assemblages) below the FO of the inoceramid bivalve species Cremnoceramus waltersdorfensis and C. deformis erectus in the Turonian–Coniacian boundary interval. The top of the M. furcatus acme was recorded below the FO of Micula staurophora. The second quantitative rise of M. furcatus (12% in assemblage) was found in the lower lower Campanian of the Pavlovské vrchy klippes above the FO of Broinsonia parca parca in the UC14a Zone and the last occurrence of the planktonic foraminifer Whiteinella baltica. Above this second acme M. furcatus disappears. The significantly earlier appearance of M. furcatus in the Silesian Basin may be connected with a southeast-heading surface current from the North European epicontinental sea where the species appeared in the early Turonian too.
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