Dinoflagellate cyst stratigraphy of the Miocene Hodde and Gram Formations, Denmark

STEFAN PIASECKI

Piasecki, S.: Dinoflagellate cyst stratigraphy of the Miocene Hodde and Gram Formations, Denmark. DGF Bull. geol. Soc, Denmark, vol. 29, pp. 53-76, Copenhagen, June 10th, 1980. A dinoflagellate cyst stratigraphy is proposed for the Hodde and Gram Formations in western Jylland, Denmark. Four biozones are defined and the formations are dated by dinoflagellate cysts to be of Middle and Upper Miocene age, which supports previous dating by molluscs. One new genus and four new species are described: Labyrinthodinium truncatum gen. nov. sp. nov., Dinopterygium verriculum sp. nov., Ap- teodinium tectatum sp. nov. and Nematosphaeropsis aquaeducta sp. nov.

Stefan Piasecki, Institut for Historisk Geologi og Palæontologi, Øster Voldgade 10, DK-1350^ København K, Danmark, January 18th, 1980. ""•''

During Miocene time the eastern margin of the been worked out in details. A planktonic North Sea Basin was located in Denmark. A foraminifera fauna, in sample 5.0-5.5 metres series of transgressions and regressions resulted below surface in the Gram boring, consists of in a series of interfingering marine and non- very small forms of Globorotalia continuosa marine deposits several hundred metres thick. Blow, Neogloboquadrina cf. acostaensis (Blow) Three main transgressions and two main regres­ and very few specimens of Globigerina bulloides sions have been recognized giving the basis for a d'Orb. and Neogloboquadrina dutetrei — group division of the Miocene sediments into six forma­ (Dr. F. Rögl, pers. comm.). This fauna corres­ tions (Sorgenfrei, 1940, 1958 and Rasmussen, ponds to the planktonic foraminiferal zones N 15 1956, 1961). - N 16, Upper Miocene. The Hodde and Gram Sediments from the final Miocene transgres­ Formations are assigned to the Middle and Upper sion in Denmark were formerly well exposed in Miocene respectively, mainly on the basis of the many clay and browncoal pits in western Jylland molluscan faunas from the lower part of the (Rasmussen, 1966), but today, only four Hodde Formation (below the Hodde clay) and localities show well exposed sections, namely, the fijom the Gram clay. The faunas are comparable Gram and Hauge claypits and the browncoal pits with the North German molluscan faunas (Ras­ near Fasterholt and Ørnhøj (fig. 1). The lower mussen, 1966). sediments consist of alternating sand and black The present work establishes a dinoflagellate clay which are overlain by the uniform black, cyst stratigraphy for these sediments. Samples bituminous Hodde clay. These two sedimen- were collected from measured sections in the pits tological units are united into the Hodde Forma­ at Hauge, Fasterholt and Ørnhøj. In addition a tion (Rasmussen, 1961). The Gram Formation number of samples from a boring at Gram made (Rasmussen, 1961) overlies the Hodde Forma­ by the Geological Survey of Denmark have been tion and consists of a basal glauconitic clay suc­ included in this investigation (DGU file 141 ceeded by the brown to grey fossiliferous Gram 423). Samples from this boring are not contami­ clay which becomes more silty toward the top. nated with sediments from higher levels, as only The Hodde clay and the glauconite clay contain the undisturbed core of each sample is used. no macrofossils, but the Gram clay is very rich in Standard palynological preparation techniques molluscan fossils. Benthonic foraminifera are were used, and residues were sieved through a 20 abundant in both the Hodde and Gram Forma­ Jim net and mounted as strew-preparations in tions (Kristoffersen, 1972). Planktonic Eukitt. The type species are stored in the foraminifera have been reported from the Gram Geological Museum of the University of clay only (Ersgaard et al, 1977), but have not Copenhagen (MGUH). 54 Piasecki: Miocene stratigraphy

LEGEND

GRAM R3RM.

> HODDE FORM.

Fig. 1. The distribution of the Hodde and Gram Formations in Jylland (after Rasmussen', 1966) and the positions of the localities, combined with the lithology and biostratigraphy. Bulletin of the Geological Society of Denmark, vol. 29 1980 55

Lithology mica-rich quartz sand, which changes into the basal gravel bed of the Hodde Formation. The Gram Hodde Formation is succeeded by glauconitic The Gram boring is 120 metres deep (fig. 2). The clay and Gram clay at one locality in the region, lower 80 metres consist, mainly, of finegrained Lavsbjerg. The strata are weakly folded, but little sand with two clay and silt dominated intervals. disturbance of the original bedding is apparent. Gravel and concretionary horizons occur as The marine sequence is terminated upward by minor constituents. Molluscs are recoverable glacial erosion (fig. 3). from two intervals and dinoflagellate cysts are found, mainly, in the clay and silts. The sandy Ørnhøj sequence is correlated with the Odderup Forma­ The uppermost part of the Odderup Formation, tion of Rasmussen (1961), which was considered the Hodde Formation and a part of the Gram to be deposited under limnic conditions. Ap­ Formation are exposed in a slightly dipping sequ­ proximately 45 metres of this sandy sequence ence in an abandoned browncoal pit at Lille contain marine fossils (fig. 2). Spåbæk (Rasmussen, 1966) west of the village The upper 40 metres of the boring provided Ørnhøj. The Odderup Formation consists of pla­ clay and silt belonging to the Hodde clay, glauco- nar cross-bedded quartsitic sand with thin lami­ nite clay and Gram clay. The Hodde Formation is nated beds of silt and clay. The Hodde Formation defined (Rasmussen, 1961) to include a sequence consists of gravel and black clay, changing into of alternating black clay and silt or fmesand be­ black, bituminous Hodde clay 0.5 metres above low the Hodde clay. Accordingly, the lower the lower boundary. Two metres of glauconitic boundary of the formation is often difficult to clay overlie the Hodde clay, and approximately place accurately. In this work, the lower bound­ one metre of Gram clay is found below the glacial ary is considered to be at the base of the first deposits which terminate the sequence (fig. 3). sequence of alternating clay and silt below the Hodde clay in the Gram boring. The upper boundary of the Hodde clay, and the boundary Biostratigraphy between the glauconite clay and the Gram clay, are precisely determined from the changes in col­ Rich and well preserved dinoflagellate cyst as­ our, pyrite and glauconite content (Ersgaard et semblages are abundant in the Hodde and Gram al.i 1977). The positions of the samples examined Formations of the Gram boring, and accordingly are shown in fig. 3. this sequence is used herein as the standard sec­ tion for the dinoflagellate cyst distribution in both Hauge the Hodde and Gram Formations. In addition, The accessible part of the section in the waterlog­ preliminary investigations of the dinoflagellate ged claypit at Hauge consists of 2 metres of flora in the underlying Odderup Formation indi­ glauconite clay and one metre of Gram clay (fig. cate the downward ranges of some species at this 3). According to Rasmussen (1966) the thickness one locality. No dinoflagellate cysts have been of the glauconite clay in this region ranges from found in the Odderup Formation at Fasterholt 1-2 metres. Therefore, the glauconite clay sequ­ and Ørnhøj. A number of species from the ence at Hauge may well be complete, though the Hodde and Gram Formations are known to occur lower boundary is not exposed. The upper part of in older deposits of the North Sea Basin, but have the Gram clay is mixed with Quaternary sedi­ not been recorded in the Odderup Formation ments. during this study. Accordingly their extensions downwards are marked on the rangechart from Fasterholt the Gram sequence with broken lines'only (fig. The Hodde clay is exposed at several localities in 4)- the Søby-Fasterholt region, where browncoal Most of the species are found throughout the was mined until 1970. The Hodde Formation sequence, but a few have a restricted occurrence. overlies the limnic Odderup Formation, which in Hemicystodinium zoharyi (Rosignol) Wall, 1967 the upper part consists of planar cross-bedded. occurs abundantly in two samples from the lowest 56 Piasecki: Miocene stratigraphy GRAM BORING

LITHOLOGY CLAY

SILT

FINE SAND

COARSE SAND AND GRAVEL

BITUMINOUS CLAY

GLAUCONITE

STRUCTURE CLAY: UNSTRUCTURED SAND: NO INFORMATION WEAK LAMINATION

INTERLAMINATED ""^ CLAï' AND SILT PLANAR '////y////.'//^////^/. f*^'*^'* CROSS-BEDDING CONCRETIONS

FOSSILS % MOLLUSCS ® DINOFLAGELLATE CYSTS POSITION OF SAMPLES

o w to (3 fig. 2. Sedimenlological section of the Gram boring (modified after Ersgaard el al. 1977). Bulletin of the Geological Society of Denmark, vol. 29 1980 57 part of the Hodde Formation (i.e. below the first trocarpum (Deflandre & Cookson) Wall, 1967 zone considered here), but has not been found at are also well represented in the assemblage. any higher level in the sequence. The last occurrence of this species may well be a useful Nematosphaeropsis aquaeducta Zone nov. marker horizon in the North Sea sediments, even Definition: Sediments containing Nematos­ though the species is the cyst of Pyrodinium phaeropsis aquaeducta sp. nov. Lower boundary bahamense Plate, 1906, which has a Recent dis­ at the first occurrence of A^. aquaeducta and up­ tribution that is highly temperature dependent. A per boundary at the first occurrence oiAchomos­ number of species occur for the first time in this phaera andalousiense Chene, 1977. sequence at 41-5 metres below the surface (fig. Reference section: Boring at Gram town: DGU 4). The exact first occurrence is to some extent file 141 423, 36.0-29.0 metres below surface. faciès dependent, as no dinoflagellate cysts have Local correlation: The zone is found in the been found in the sand between 41.5-45.0 Hodde clay, 4 metres thick, at Fasterholt and in metres. the upper 4 metres of the Hodde clay at Ørnhøj. Stratigraphical range: Middle Miocene above Labyrinthodinium truncatum Zone nov. Labyrinthodinium truncatum Zones nov. and Definition: Interval from the first occurrence of below Achomosphaera andalousiense Zone nov. Labyrinthodinium truncatum gen. nov. sp. nov. to Remarks: Achomosphaera alcicornu (Eisenack) the first occurrence of Nematosphaeropsis Dacey & Williams, 1966 and gen. et sp. indet. aquaeducta sp. nov. occur for the last time close to the upper bound­ Reference section: Boring at Gram town: DGU ary of this zone, and the dominating species of the file 141 423, 42.0-36.0 metres below surface. zorie S. placacantha occurs for the last time at the Local correlation: The lower 2.5 metres of the upper boundary, together with L. truncatum and Hodde Formation at Ørnhøj is included in this N. aquaeducta. zone. Stratigraphical range: Middle Miocene below N. Achomosphaera andalousiense Zone nov. aquaeducta Zone nov. Definition: Interval from the first occurrence of Remarks: Tectatodinium pellitum Wall, 1967, Achomosphaera andalousiense Chene, 1977 to Apteodinium tectatum sp. nov., Spiniferites the first occurrence of Dinopterygium verriculum mirabilis (Rossignol) Wall, 1967 and Labyrin­ sp. nov. thodinium truncatum gen. nov. sp. nov. occur for Reference section: Boring at Gram town: DGU the first time at the lower boundary of this zone in file 141 423, 29.0-20.0 metres below the surface. the Gram sequence. T. pellitum is found through­ Local correlation: All the exposed sediments of out the Gram sequence, but A. tectatum and S. the Gram Formation at Hauge and Ørnhøj (ap­ mirabilis are restricted to the L. truncatum Zone proximately 3 metres) and the lower 4 metres of in the Gram sequence, though they are known to the Gram Formation at Fasterholt belong to this occur higher in the sediments at Fasterhold and zone. Ørnhøj. Distatodinium paradoxum (Brosius) Stratigraphical range: Upper Miocene above the Eaton, 1976 occurs for the last time in this zone Nematosphaeropsis aquaeducta Zone nov. and and may be stratigraphical useful. It is not be­ below the Dinopterygium verriculum Zone nov. lieved to be redeposited because it occurs in most Remarks: A. andalousiense is abundant in the of the Lower to Middle Miocene samples from Gi'am sequence from its first occurrence up to 22 southern Jylland. Tectatodinium psilatum Wall & metres below the surface, whereas it occurs more Dale, 1973, Spiniferites sp. B. and gen. et sp. in- sporadically higher in the sequence. The last det. occur for the first time in this zone. The di­ occurrences of Spiniferites sp. A, Spiniferites sp. noflagellate assemblage of this zone and the B, Cyclopsiella elliptica Drugg & Loeblich, 1967 overlying zone are dominated by Systematophora and Pentadinium laticinctum Gerlach, 1961 are placacantha (Deflandre & Cookson) Davey, found in this zone, but apparently the exact posi­ Downie, Sarjeant & Williams, 1969. Lin- tions of these last occurrences vary within the gulodinium machaerophorum (Deflandre & zone at the different localities. Cookson) Wall, 1967 and Operculodinium cen- 58 Piasecki: Miocene stratigraphy

GRAM BORING

0.

FASTERHOLT

HAUGE ØRNHØJ

30.

40.

Fig. 3. Sedimentoîogical sections of the Hodde and Gram Formations at Gram, Hauge, Fasterholt and Ørnhøj with the positions of samples. Legend see fig. 2. GRAM SECTION ODDERUP FORMATION HODDE FORMATION GFl<\M FCRMATION GLAUC I HODDE CLAY CLAY GRAM CLAY Position of samples r 1 t 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 I 1 1 1 1 1 1 1 1 1 1 1 45 Lingulodinium mochaerophorum Operculodinium centrocarpum Cannosphaeropsis sp. A Williams & Brldeaux, 1975 Homotryblium cf. plect-Mum I Cordosphaeridîum minimum Spiniferites pseudofurcotus Hyslrichosphaercpsis obscura Hystrichokolpoma rigaudlae Operculodinium sp. Tuberculodinium rossignoliae Melîtasphaeridium choanophorum Lejeunia sp. cf. Cleistosphaeridium ancoriferum o. Tecfatodinium pellitum Tectotodinium psi latum 3 Palaeocystodînium golzowense 5i Pentadînium laticinctum Spiniferites sp. A Cyclopsiella elliptica Spiniferites sp. ß Systematophora placacantha Achomosphaera a Icicornu Disfatodinium pcradoxum Spiniferites mirabilis Apteodinium teetotum sp. nov. Labyrinthodinium truncatum sp. nov. Gen, et sp. indet. Nematosphaeropsis aquoeducta sp. nov. Achomosphaera anda lousiense Dinopterygium verriculum sp. nov, cf. Polysphaeridium pastielsii Hemicystodinium zoharyi

Pediastrum sp. Ovoidites sp. L. truncatum N. aquaeducta A. andalou­ D. vemculum Zone Zone siense Zone Zone 60 Piasecki: Miocene stratigraphy

RANGE OF SELECTED SPECIES AT:

FASTERHOLT HAUGE ØRNHØJ

E a 3 C TZ 11) ï ji O e o _N c a- 1^ O ^ a> 0) •^o ° g. • • E n Q- Q. 3 S ^ S--i .à-" 2 2.2 o E O I c .2 3-2 « ».-5 —-s c u (u o I -Q 9-^ .- .- -c •is" g 5o ^s ^s •.= III Ö c o o „ Q. Q.-S Ol a. ^^..^o 5.>x"oy -S-a. u I X < I— t/1 to —I i-tt.C)

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f/g. 5. Distribution of selected dinoflagellale cysts in the Hodde and Gram Formations at Hauge, Fasterholt and Ømhøj. Bulletin of the Geological Society of Denmark, vol. 29 1980 61

Dinopterygium verriculum Zone nov. Formations and the ranges reported by Harland Definition: Sediments containing Dinopterygium (1978). verriculum sp. nov. The lower boundary at the The last occurrence of 5. placacantha (recorded first occurrence of D. verriculum. The upper as S. ancyrea by Harland, 1978) and the first boundary is tentatively defined at the last occurrence of A. andalousiense at the boundary occurrence of D. verriculum. between the Middle and Late Miocene (Harland, Reference section: Boring at Gram town: DGU op.cit.) are considered to be of major importance file 141 423, 20.0-5.0 metres below the surface. in dating the Hodde and Gram Formations since Glacial erosion and Quaternary sediments termi­ both cysts occur frequently in their respective nate the section upward. sediments. The distribution of the two species in­ Local correlation: The Dinopterygium verriculum dicate that the boundary between the Hodde and Zone is found in the Gram Formation at Fas­ Gram Formations corresponds to the boundary terholt from 4 metres above the lower boundary between the Middle and Late Miocene, and con­ to the top of the sequence. firms previous datings (Rasmussen, 1966). Simi­ Stratigraphical range: Upper Miocene above larly, Harland (1978) reports N. aquaeducta to Achomosphaera andalousiense Zone nov. occur for the first time at the boundary between Remarks: The upper boundary of the zone has the Early and Middle Miocene. The first not been determined at Gram because the zone is occurrence of this species in the lower part of the restricted upwards by erosion and mixing with Hodde clay therefore may indicate a Middle glacial sediments. The last occurrence of Miocene age for the Hodde clay and an Early Palaeocystodinium golzowense Alberti, 1961 is Miocene age for the lower part of the Hodde found in this zone. Formation and the Odderup Formation at Gram. The disappearance of T. pellitum, T. psilatum However, Manum (1976) reports a range of N. and A. andalousiense in the upper part of the aquaeducta corresponding to the upper part of Gram sequence is believed to be caused by local Middle Miocene only. environmental changes, as the species are re­ On the Grand Banks, New Foundland, Wil­ ported from younger sediments (Harland, 1978, liams & Brideaux (1975) found the last Wall, Dale & Harada, 1973). The dinoflagellate occurrence of P. laticinctum, C. elUptica and P. cyst assemblage in XhtA. andalousiense Zone and golzowense in the middle of Late Miocene, and the D. verriculum Zone is dominated by Homo- Polysphaeridium pastielsii Davey & WilUams, tryblium cf. plectilum and in some levels of D. 1966 was found to the end of Late Miocene. This verriculum. is comparable with the last occurrences of these species at Gram. It should be noted, however, that several other species have a distribution on Grand Banks, which is different from that in the Age of the Hodde and Gram Gram sequence. Formations

The number of papers dealing with dinoflagellate Environment cyst stratigraphy in the Miocene is limited. Nevertheless, a number of species have been The use of dinoflagellate cysts as a tool for shown to be of some stratigraphie importance. palaeoenvironmental interpretations is as yet Harland (1978) published Neogene range charts, very limited. Few investigations of the relation based on his own work and the more important between the dinoflagellate cysts and the papers of Neogene dinoflagellate cyst stratig­ palaeoenvironment have been published (Dow- raphy from the Northwest European continental nie et al., 1971). However, the Miocene dino­ shelf and adjacent areas. Several species ap­ flagellate cyst assemblages have many species in peared to have a restricted range in the Miocene, common with Recent sediments, and the dis­ but only some of these occur in the Hodde and tribution of Recent dinoflagellates and their Gram Formations. There are also differences in cysts, mainly in the North Atlantic region, is fairly the occurrences found in the Hodde and Gram well known (Reid, 1974, 1977, Harland, 1977 62 Piasecki: Miocene stratigraphy and Wall, Dale, Lohmann & Smith, 1977). From cially in the Gram boring. Three intervals may be these works it is evident that it is mainly the distinguished on the basis of the variations in the dominating species which may be used to content of dinoflagellate cysts relative to the characterize the palaeoenvironment, since the content of pollen and spores as well as dissemi­ diagnostic species also occurs outside the specific nated cuticles and tracheides. The glauconite clay environment. Wall et al. (1977) found several and the lower 4 metres of the Gram clay contains species useful as environment indicators. very small amounts of terrestial plant material, in The dominating species in the Hodde and contrast to the remaining part of the Gram clay, Gram Formations (5. placacantha, H. cf. plec- which has a high content of terrestial plant mat­ tilum and D. verriculum) are not known to occur erial and decreasing amounts of dinoflagellate in Recent sediments. Lingulodinium cysts toward the top of the sequence. The content machaerophorum and Operculodinium cen- of terrestial plant material relative to the content trocarpum, which are well represented through of dinoflagellate cysts, in the Hodde Formation, the sequence, are well known in Recent sedi­ is intermediate compared to the two intervals ments. They are characterized as cosmopolitan mentioned above. species in estuarine and neritic environments re­ A similar trend appears from the variations in spectively (Wall et al., 1977). the content of freshwater green algal remains. Bitectatodinium tepikiense Wilson, 1973 is Ovoidites sp. is common throughout the Hodde found in the Hodde clay at Ørnhøj only. Appar­ Formation, and both Ovoidites sp. and Pedias- ently it has a northerly distribution in the Atlantic trum sp. are common in the upper part of the region, probably preferring temperate to cool Gram Formation, whereas in the intermediate temperate conditions (Harland, 1977). Dale part of the sequence, these genera have not been (1976) has shown from his study of the Trond­ recorded. A similar division has not been recog­ heim Fjord and the shelf outside the ^ord that B. nized at the other localities. tepikiense occurs at the shelf only and not in the As marine cysts are present throughout the fjord. The occurrence of B. tepikiense at Ørnhøj, sequence at Gram, variation in terrestial plant therefore may indicate somewhat more open material content most likely reflects the variation marine conditions at this locality during the in the amount of freshwater flowing into the sea sedimentation of the Hodde clay than at the other at Gram, or in other words, changes in the drain­ three localities. age of the coastal land area. The presence of high numbers of dinoflagellate H. zoharyi has been shown to be the cyst of the cysts through the main part of the sequence, and motile dinoflagellate Pyrodinium bahamense the conditions preferred by the species men­ Plate, 1906, which is living in littoral embay­ tioned above, indicate a marine estuarine deposi- ments in tropical to subtropical regions (Wall & tional environment for the Hodde clay, glauco- Dale, 1969). Fossil B. tepikiense is reported only nite clay and the lower part of the Gram clay. from temperate to cold temperate regions and its This is in good accordance with the positions of Recent occurrence seems to be restricted to these the localities in embayments close to the coast areas as well (Dale, 1976). The presence of H. (eastern margin of present occurrence; Rasmus- zoharyi, which is confined to the lowest part of sen, 1966). the Hodde Formation at Gram, in contrast with T. psilatum is reported to occur in fresh to the isolated occurrence of B. tepikiense, in the brackish water in the Black Sea during the late Hodde clay at Ørnhøj only, could indicate a Quaternary (Wall & Dale, 1973). The occurrence temperature decrease during the sedimentation of T. psilatum in the Hodde and Gram Forma­ of the Hodde Formation. This would agree tions could mean either that the environment was closely with the temperature variation curve re­ brackish, or that the cysts were transported into cently presented by Buchardt (1978). This curve the sea from coastal swamps or lakes. As the cyst shows a decrease in temperature from Middle assemblage otherwise appears to be marine, the Miocene into Upper Miocene, with a minimum latter explanation is assumed to be correct. temperature corresponding to the lowermost part of the Gram clay. The content of terrestial plant material in the Hodde and Gram Formations is variable, espe­ It appears from the distribution of the dino- Bulletin of the Geological Society of Denmark, vol. 29 1980 63 flagellate cysts that the lower boundary of the Diagnosis: Spherical to ovoïàdX Apteodinium with Hodde clay is younger at Fasterholt than at Gram a short and broad apical horn. The wall is dif­ and Ørnhøj. This may be because the Hodde ferentiated into three units. The middle unit con­ Formation is the basal part of the uppermost sists either of spongeous tissue with internal Miocene transgression described by severar au­ channels or short "processes" separating the in­ thors (Rasmussen, 1966, Koch et al., 1973, As- ner and outer unit. Paracingulum and parasulcus gaard & Bromley, 1974). The upper boundary of are clearly differentiated. The archaeopyle is pre- the Hodde Formation coincides with the bound­ cingular: Type P. ary between N. aquaeducta Zone and .«4. an- dalousiense Zone in all the sequences examined. Description: Proximate cysts with spherical to So the termination of the Hodde clay sedimenta­ ovoidal capsule, with a short and broad apical tion seems to have taken place at approximately horn. Three wall layers may be recognized. The the same time all over the area. The upper endophragma is thick, massive and hyaline, and boundary of the Hodde clay is used as a marker separated from the periphragma by short "pro­ horizon in the North Sea basin (Rasmussen, cesses", low walls or spongeous tissue with inter­ 1974), and on the basis of the present evidence it nal channels. All intermediate structures have may be'regarded as an isochrone. been observed, but the wall structures are gener­ The difference in thickness of the Hodde clay ally uniform in one specimen. The internal walls at Fasterholt and at Ømhøj, reflects the differ­ and processes are buccinate in optical sections ence in the length of time during which this par­ because they are expanded proximately and dis- ticular type of sedimentation prevailed. tally. The periphragma is thin and finely foveol- Nevertheless, the increased thickness of the ate. The thickness of the cyst wall varies from 2 to Hodde clay at Gram also reflects a somewhat 6 |im. higher rate of accumulation, because the N. The apical horn is mainly formed by the peri­ aquaeducta Zone is slightly thicker at Gram than phragma and the middle wall unit, but a weak at the other localities. bulge may be present in the endophragma below While local variations in the sedimentation the horn. The length of the apical horn varies rates therefore seem to have been limited during from 2 to 14 (xm. the sedimentation of the Hodde clay, they be­ No parasutural structures have been observed, came more pronounced during the sedimentation except for the thickenings of the middle wall unit of the Gram Formation. The A. andalousiense along the sides of the paracingulum. The Paracin­ Zone is twice as thick in the Gram sequence as in gulum and the parasulcus are grooved and the Fasterholt sequence. This suggests that the de­ structure of the middle wall unit may be absent in creasing amount of dinoflagellate cysts in the up­ these areas. The paracingulum is helicoidal and per part of the Gram clay at Gram may be caused narrow. The endo- and periphragma may be in by a combination of unfavourable environmental contact in the parasulcal area. conditions (i.e. freshwater influx) and dilution of The archaeopyle is pentagonal to trapezoidal the assemblage by increased sedimentation rate. and the posterior margin is in contact with the paracingulum. Shape and position of the ar­ chaeopyle indicate that it is formed by the loss of Systematic description paraplate 3". The archaeopyle formula is P.

Only dinoflagellate cysts, which are important to Discussion: Apteodinium tectatum sp. nov. differs the stratigraphy in this paper, are treated herein. from other species of the genus by the combina­ The taxonomy follows that proposed by Stover & tion of the helicoidal paracingulum, the presence Evitt, 1978. of a well defined parasulcus, the apical horn and the wall structure. The genus Pyxidiella Cooksen Apteodinium tectatum sp. nov. & Eisenack, 1958 has an intercalary archaeopyle PI. 2, fig. 1-6. and no apical horn. 1977 cf. Pyxidiella Chene, textfig. 4, 9, PI. 1, fig. The homology of wall layers in dinoflagellate 12. cysts is not well understood yet, and the ter- 64 Piasecki: Miocene stratigraphy

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8 PLATE 1. Figs 1-3. Nematosphaeropsis aquaeducta sp. nov., holotype, MGUH 14961, high, medium and low focus 1000 x Figs 4-8 fo«Å''x'T"'? T',^T'^"'Z:,',uf.tr^- f ""W'^^'»-'««'"™. ^Igh and low focus, 500 X. Fig. 6. Pentagonal antapical paraplate WOO X. Figs 7-8. Holotype, MGUH 14958, high and low focus, 500 x. c *- *•

PLATE 2. Figs 1-6. Apteodinium tectatumip. nov. Figs 1-3. Paratype, MGUH 14957, high, medium and low focus, 500 X. Figs 4-6. Holotype, MGUH 14956, high, medium and low focus, 500 X. Fig. 7. Cyclopsiella elliptica, 1000 x. Fig. 8. Achomosphaera andalousiense, 500 X. Figs 9-11. Labyrinthodinium truncatum gen. nov. sp. nov., holotype, MGUH 14959, high, medium and low focus, 1000 X. ^ o td b TI 5' o

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C/5 O o S' o ' 'w. 3 i ''• --^. 3

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•C ' K t' ^ x,^ r 't-- 00 *^Ä lif^^ o 66 Piasecki: Miocene stratigraphy minology (Evitt et al., 1977) is therefore not al­ fit into the diagnose of/, rugosum. The type of ways definitive. In this case the terminology of archaeopyle has not been determined. the wall layers is dependent on the interpretation Dimensions: (n=15) Diameter of capsule 18-28 of the middle wall unit. I have chosen to regard urn, length of processes 12-18 um. the wall cavity as being a reduced pericoel, and to regard the structures of the middle wall unit as not being "regular processes", because the mid­ dle wall unit also appears as a more common wall Dinopterygium verriculum sp. nov. structure (spongeous), which may be a part of PL 1, fig. 4-8, PI. 5, fig. 5-6. periphragma. The inner and outer wall layers are therefore endo- and periphragma respectively. Diagnosis: A species of Dinopterygium with thin, The wall of Dinopterygium verriculum sp. nov., hyaline wall layers, separated by pillars or low which is discussed later in this paper, is interpre- membranes, forming a reticulate pattern. The tated in the same way. outer wall layer may form low fenestrated parasutural membranes, but no large and ex­ Holotype: PI. 2, fig. 4-6. Size: length 65 ^im, tending cingular membranes are present. The ar­ breadth 59 um, length of apical horn 9 (xm. chaeopyle is epicystal; Type tA+tPa. MGUH 14956. Paratype: PI. 2, fig. 1-3. Size: length 88 (xm, Description: A proximate to proximochorate breadth 77 um, length of apical horn 6 (im. cyst, with a rounded to pentagonal shape in MGUH 14957. aequatorial view, and ovoidal shape with the Size variation: (n=15) length 63 (74) 90 \xm, parasulcal area slightly grooved in polar view. breadth 51 (62) 77 um, length of apical horn 2 The cyst wall is differentiated into three units. (6) 14 iJim. Endophragma and periphragma are thin and Type locality and type stratum: Denmark, Gram, hyaline, and separated by short "processes" or Gram boring (DGU file 141423) 42.0-35.5 m low membranes. A spongeous tissue occurs very below surface, Hodde Formation. seldom. The middle wall unit form a reticulate Stratigraphical range: Middle Miocene, pattern with varying mesh size. The surface of the Labyrinthodinium truncatum Zone and cyst is smooth or finely punctate. Nematosphaeropsis aquaeducta Zone. The paratabulation may be determined from variations in the structure between endo- < and periphragma or from parasutural membranes Cannosphaeropsis sp. A. Williams & Brideaux, formed by upfolding of the periphragma. The 1975. parasutural membranes on the surface of the cyst 1975 Cannosphaeropsis sp. A. Williams & are 1 to 2 (xm high, but occasionally up to 6 [xm Brideaux: PI. 15, fig. 4, PI. 17, fig. 10. high. They are densely perforated. The paracin- Remarks: A number of cysts in the Gram sequ­ gulum and parasulcus are not differentiated into ence correspond in size as well as morphology to paraplates except for paraplate ps. The para­ the species figured by Williams & Brideaux tabulation formula is determined to be (3(4)', 6", (1975). The processes are branched distally sev­ ?c, 5'", ps, Ip, 1""). The apical paraplates have eral times into extremely delicate threads, which only been observed on one occasion, because the are easily broken and hardly visible. It has been epicyst is disintergrated into single paraplates difficult to find specimens, which, without doubt, during archaeopyle formation, and only excysted have these threads connected from one process to specimens have been found. The paracingulum is another as trabeculae. The cysts are also very slightly hélicoïdal, and the parasulcus is slightly similar to the specimens figured by Manum grooved. The position of paraplates ps and Ip and (1976) as Impletosphaeridium rugosum the shepe of 1"" indicate a pyrodinium-type of Morgenroth, 1966 znA Impletosphaeridium sp. 1, tabulation (Evitt, 1976). The archaeopyle is epi­ because the processes may or may not possess a cystal and the archaeopyle formula is tA+tPa. distal platform from which the branching occurs. Varying numbers of precingular paraplates may In other characters, however, these cysts do not remain attached to the hypocyst after the ar- Bulletin of the Geological Society of Denmark, vol. 29 1980 67 chaeopyle formation. The parasulcus form a membraneous processes arise. All the processes minor sulcal flap at the margin of. the hypocyst. are of equal length and slightly expanded distally into small platforms. The archaeopyle is large and Discussion: Dinopterygium verriculum sp. nov. polygonal of type t A. differs from other species of the genus by the wall structure and by the absence of a single com­ Description: Endophragma is of constant thick­ pound operculum. ness, whUe periphragma may be thin and smooth or thick and spongeous. The wall thickness range Holotype: PI. 1, fig. 7-8. Size: length 63 \im excl. from 1-3 um, mainly because of the variation of apical area, breadth 77 (im. MGUH 14958. periphragma. The two wall layers are not clearly Size variation: (n=25) length 51 (56) 6 um excl. separable when periphragma is thin and smooth. apical area, breadth 50 (62) 77 \im. The crests on the surface of the cysts may Type locality and type stratum: Danmark, either form a dense reticulum with a large Gram, Gram boring (DGU file 141 423), number of processes or a rude pattern with open 20.0—5.0 m below surface, Gram Formation. meshes and few processes. The reticulum may Stratigraphical range: Upper Miocene, Dinop­ reflect a undeterminable paratabulation, because terygium verriculum Zone. some of the crests appear to form a superior pat­ tern from which the processes arise. Further, the Labyrinthodinium gen. nov. archaeopyle sutur does not cross the crests, which PI. 2, fig. 9-11, PI. 3, fig. 2, PI. 6, fig. 3-4. are conformable with the archaeopyle margin and Diagnosis: Small chorate cysts with spherical partly with the accessory archaeopyle sutures. main body and apical archaeopyle. The cyst wall The processes are formed of several adjoining is two layered, and periphragma forms a closed or crests or membranes, and are all of the same open reticulum of anastomosing crests. The length on one cyst. They are expanded distally, smaller crests support the larger ones, which form building up a small platform. membraneous processes of equal length. No structures reflecting paratabulation, paracingulum or parasulcus have been observed, Type species: Labyrinthodinium truncatum gen. except for the archaeopyle sutures. The ar­ nov. sp. nov. chaeopyle is apical: type tA. It is large and polygonal, and small accessory sutures are pre­ Remarks: Labyrinthodinium gen. nov. is similar sent along the margin. to the Upper Jurassic genus Epiplosphaera Kle- ment, 1960, but the reticulum on the cyst surface Discussion: These cysts do not belong to Cordos­ oi Labyrinthodinium is not as well developed as phaeridium (Eisenack) Davey, 1969, because in Epiplosphaera. The spherical main body and they do not have intratabular fibrous processes the membraneous processes are also different and a precingular archaeopyle. from Epiplosphaera, and a large time gap is furthermore separating the two genera. Holotype: PI. 2, fig. 9-11. Diameter 25 um, length of processes 5 p,m, wall thickness 1 [im. Labyrinthodinium truncatum sp. nov. MGUH 14959. PI. 2, fig. 9-11, PI. 3, fig. 2, PI. 6, fig. 3-4. 1976 Cordosphaeridium sp. 2 Manum, PI. 3, fig. Paratype: PI. 3, fig. 2. Diameter 40 jim, length of 4-5. processes 10 \aa, wall thickness 3 (im. MGUH 14960. Diagnosis: Small chorate cysts with spherical Size variation: (n=30) Diameter 23 (29) 40 (im, main body, composed of two wall layers. Endo- length of processes 4 (6) 10 (xm, wall thickness phragma is hyalin and structureless, Periphragma 1-3 microns. is smooth to spongeous at the surface of the main Type locality and type stratum: Denmark, Gram, body, and smooth with scattered microgranulaes Gram boring (DGU file 141 423) 42.0-29.0 m when forming crests and processes. Periphragma below surface, Hodde Formation. forms an open reticulum of crests from which Stratigraphical range: Middle Miocene, 68 Piasecki: Miocene stratigraphy

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7 8 PLATE 3. Fig. i. Bitectatodinium tepikiense, 500 X. Fig. 2. Labyrinthodinium truncatumgen. nov. sp. nov., paratype, MGUH 14960, 500 x. Fig. 3. Gen. et sp. indei., 500 x. Fig. 4. cf. Cleistospliaeridium ancoriterum, 500 X. Fig. 5. Spiniterites sp. A, 500 X. Fig. 6. Opercutodinium sp., 500 x. Fig. 7. cf. Polysphaeridium pastielsii, .500 X. Fig. 8. Systematophora placacantha 500 x.

PLATE 4. Fig. 1. Tectatodinium pellitum 500 X. Figs 2-3. Tectatodinium psilatum 500 X. Fig. 4. Pediastrum sp. 500 X. Fig. 5. Ovoidites sp. 500 X. Figs 6-7. Fungi 500 X. ^ td c

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1^ ^ 00 JÊÊÊÊÊmm ca 70 Piasecki: Miocene stratigraphy Labyrinthodinum truncatum Zone and detached. The archaeopyle formula is P. The Nemathosphaeropsis aquaeducta Zone. paratabulation formula, determined from the arrangement of the trabeculae, is (4', 6", 6c, 5'", Hystrichosphaeropsis obscura Habib, 1972. Ip, 1""). Paracingulum is hélicoïdal. PI. 4, fig. 8. 1972 Hysterichosphaeropsis obscura Habib, p. Discussion: Nematosphaeropsis aquaeducta sp. 379-380, PI. 21, fig. 1-3. nov. differs from other species of the genus Remarks: A few morphological variations, which Nematosphaeropsis by its short, simple and stout have not been mentioned in the description of processes and trabeculae. Baltes (1969) figures a this species (Habib, 1972), have been observed. specimen identified as Nematosphaeropsis bal­ Specimens with reduced epi- and hypocoels have combiana Deflandre & Cookson, 1955. How­ been found. The sculpture of both peri- and en- ever, it appears from the figures that this speci­ dophragma may be coarsely granular or com­ men has the short and stout processes and pletely smooth. The endocyst may possess a small trabeculae here used to define N. aquaeducta sp. massive, hyaline apical horn. nov. instead of the long and thin processes and trabeculae typical of TV. balcombiana. The age of Nematospheropsis aquaeducta sp. nov. the specimen is Tortonian. PI. 1, fig. 1-3, PI. 5, fig. 1-2. Manum (1975) figured a specimen similar to 1969 Nematosphaeropsis balcombiana: Baltes, N. aquaeducuta sp. nov. and identified it as Lep­ PI. 3, fig. 1-3. todinium sp. 5. The genus Leptodinium is defined 1976 Leptodinium sp. 5 Manum: PI. 1, fig. as having suturai crests, so, therefore, this species 19-20. cannot be included in the genus. Diagnosis: A Nematosphaeropsis with short and stout processes connected distally by stout Holotype: PI. 1, fig. 1-3. Size: Total, length 39 trabeculae, which are triangular in cross section. Jim, breadth 38 |xm. Central body, length 27 (im, Parasutural structures are missing on the central breadth 26 (im MGUH 14961. body. Size variation: (n=15) Total, length 38 (40) 47 (im, breadth 32 (36) 45. Central body, length 27 Description: Chorate cysts with spherical to (32) 37 (im, breadth 24 (29) 36 (im. slightly ovoidal central bodies and suturai pro­ Type locahty and type stratum: Denmark, Gram, cesses and trabeculae forming an outer sphere. Gram boring (DGU file 141 423) 36.0-29.0 m Only one wall layer is visible in the light micro­ below surface, Hodde Formation. scope. No structures are visible in the wall. The Stratigraphical range: Middle Miocene, surface is smooth or punctate. Nematosphaeropsis aquaeducta Zone. Gonal and intergonal processes are present and no parasutural structures connect the bases of the Operculodinium sp. processes. A few of the processes show a small PI. 3, fig. 6. proximate cavity, otherwise they are massive and Remarks: A small ovoidal cyst with precingular buccinate. The processes are short and stout, and archaeopyle. The surface is smooth and covered angular in cross section. Distally they expand into with short, massive, subconical processes, prob­ connecting trabeculae, which make the ably intratabular in position. As Operculodinium paratabulation clearly visible. The trabeculae are species may have 1,2, or 3 precingular paraplates triangular in coss section with one angle pointing involved in the archaeopyle formation, this against the capsule. The outer side of the species may correspond to Operculodinium sp. 2 trabeculae is concave, especially above the pro­ Manum, 1976, PI. 1, fig. 21, which has a 2P ar­ cesses, giving rise to a shape similar to the shape chaeopyle. of the roman aquaducts. The length of the pro­ Dimensions: (n=12) Length of capsule 33—39 cesses are 9-12 (im, and uniform within a single (im, length of processes 3-5 (im. specimen. The archaeopyle is formed by the loss of Palaeocystodinium ct. golzowense Alberti, 1961. paraplate 3" and the operculum is completely Remarks: Palaeocystodinium cf. golzowense from Bulletin of the Geological Society of Denmark, vol. 29 1980 71 the Hodde and Gram Formations differs from the Hysterichosphaera crassipellis Gerlach, 1961, type material with respect to its size and weak Abb. 16, 17, 22 {now Achomosphaera) and Haf- granulation of the distal part of the apical horn. niasphaera hyalospinosa Hansen, 1977. Alberti (1961) did not report cysts shorter than Dimensions: (n=10) Length of capsule 36-45 125 microns. The length of P. cf. golzowense in |im, length of processes 17-26 (im, wall thickness this material is 90-140 [xm, and the majority of 1-2 Jim. the specimens are between 100-120 jim, long. The antapical horn may have a sudden reduction Spiniferites sp. B. in thickness approximately at the middle. PI. 6, fig. 2. Morphologically this may correspond to the Description: A very thin walled Spiniferites with small second antapical horn which is present in processes of the same type as Spiniferites some Palaeocystodinium species, as f. inst. P. pseudofurcatus (Klumpp) Sarjeant, 1970, but benjaminii and P. australinum. with very high parasutural membranes connect­ ing the processes. The membranes may be as high as the processes, which then are without distal Spiniferites sp. A. trifurcation. Scattered fenestrae occur at the PI. 3, fig. 5. membranes. The determination of the paratabu­ Description: A Spiniferites with extremely va­ lation is difficult, because of the very thin peri- riable morphology. The capsule is spherical to and endophragma, but is supposed to be (?', 6", ovoidal. Periphragma and endophragma are thin, 6c, 5'", 1""). A superficial similarity to Spinifer­ smooth and structureless; but endophragma may ites cruciformis Wall & Dale, 1973 may occur, be densely foveolate — vesiculate. Periphragma due to the morphology and distribution of the may form low suturai thickenings or be folded up processes. However, a cruciform capsule has into membranes, which may be so broad that the never been observed. The archaeopyle is precin­ periphragma is in contact with the endophragma gular: Type P. only in small areas in the middle of the para- Dimensions: (n=18) Length of the capsule plates. On the other hand cysts have been 18-40 urn, length of processes 12-20 [im. observed without parasutural structures at all. The processes are massive and trifurcate dis- Gen. et sp. indet. tally. A varying number of vesicles, but generally PI. 3, fig. 3, PI. 6, fig. 5-6. one or two, are present at approximately the Remarks: A small spherical to ovoidal cyst with middle of the process stem, which may bulge out. precingular archaeopyle. The surface is finely The vesicles may be restricted to a few of the granular and covered with discontinuous crests, processes or be completely absent. The cavity probably reflecting paratabulation. from the suturai membrane may reach into the Dimensions: (n=10) Length of capsule proximal part of the process, disappearing 28-36nm, wall thickness 1-2 [im, height of crests rapidly. A small proximate cavity piay be present 4—6 [im. when no suturai structures are present. The pro­ cesses are generally round in cross section, but Other algae. specimens with processes which are triangular in Ovoidites (Potonié) Krutzch, 1959. cross section have been found. Ovoidites sp. The paratabulation has been determined as PI. 4, fig. 5. (3(4)', 6", 6c, 5'". Ip, 1""). The archaeopyle is Remarks: The genus Ovoidites has been shown to precingular: Type P. be the zygospore of zygnematacean greenalgae Spirogyra sp. (van Geel, 1976 and van Geel & Discussion: The spectacular property of these van der Hammen, 1978). As the Zygnematales cysts, the vesicles in the process stem, cannot be occur in freshwater only, the zygospore formation used as diagnostoc character because similar must occur in freshwater only, the zygospore structures are noted in a number of other species: formation must occur in freshwater and Ovoidites Spiniferites hyperacanthus (Deflandre & Cook- sp. in the present material must have been trans­ son) Cookson & Eisenack, 1974, PL 22, fig. 1, ported into the sea. 72 Piasecki: Miocene stratigraphy

PLATE 5. Figs 1-2. Nematosphaeropsis aquaeducta sp. nov. Fig. 1. Dorsal view 1650 X. Fig. 2. Trabeculae 4100 X. Figs 3-4. Cyclopsiella elliptica. Fig. 3. Aggregated group 580 X. Fig. 4. Aperture and surface sculpture 1600 X. Figs 5-6. Dinopterygiuni verriculumsp. nov Fig 5. 870 X. Fig 6. Wall structure 1050 x. Bulletin of the Geological Society of Denmark, vol. 29 1980 73

PLATE 6 Fig. 1. Operculodinium centrocarpum 900 X. Fig. 2. Spiniferites ipi. B 1000 X. Figs 3-4. Labyrinthodinium truncatumgen. nov. sp. nov. Fig. 3. 1300 X. Fig. 4. Details of surface and processes 9000 X. Figs 5-6. Gen. et sp. indet. Fig. 5. 1800 X. Fig. 6. Details of surface and membranes 9000 X. 74 Piasecki: Miocene stratigraphy

Pediastrum Meyen, 1829. Dansk sammendrag Pediastrum sp. PI. 4, fig. 5. Hodde og Gram Formationerne er aflejret under den sidste Miocæne transgression ind over vest Jylland. Formationerne er Remarks: The coenobia of the planktonic, let genkendelige på grund af rækkefølgen af sort, bituminøst freshwater greenalgae Pediastrum has been re­ Hodde 1er efterfulgt af grønt glaukonitisk 1er og brunt til gråt fossilrigt Gram 1er. Denne marine lagserie indeholder velbeva­ corded from Cretaceous to Recent in sediments rede dinoflagellat cyster i store mængder. På grundlag af ens­ deposited in marine environment (Evitt, 1963). artede variationer 1 indholdet af dinoflagellate cyster på de fire As was the case with Ovoidites sp. this material lokaUteter, hvor formationerne er blottet i dag, er der opstillet 4 biozoner, som forventes at være anvendelige i Nordsø bassinet. must have been transported into the sea. En ny slægt og fire nye arter beskrives. I overensstemmelse med tidligere dateringer på grundlag af mollusker dateres Hodde Formationen på grundlag af dinoflagellat cyster til at være af Fossil Fungi. Mellem Miocæn alder og Gram Formationen til at være af Øvre PI. 4, fig. 6-7. Miocæn alder. Remarks: Fungal spores occur in many samples Aflejringsmiljøet antages at være estuarint under delvis ind­ flydelse af tilstrømmende ferskvand, især i den øverste del af but have not been recorded in any detail. Larger Gram Formationen. En generel aftagen af temperaturen i løbet remains, very similar to the fruit bodies reported af aflejringen af Hodde Formationen antydes af cyste indholdet. by van Geel & van der Hammen (1978), are less common but include their Type 8F cf. Stromiopeltis as well as Type 8E.

Incertae sedis. Cyclopsiella elliptica Drugg & Loeblich, 1967. PI. 2, fig. 7, PI. 5, fig. 3-4. References 1967 Cyclopsiella elliptica, Drugg & LoebUch, p. Alberti, G. 1961: Zur Kenntnis mesozoischer und alttertiärer 190, PL 3, fig. 1-6. Dinoflagellaten und Hystrichosperidcen von Nord- und Mitteldeutschland sowie einigen anderen europäischen Remarks: Cyclopsiella elliptica is found both as Gebieten./"fl/aeomograp/iico, i4fc<. A, 116: 1-58. isolated specimens and aggregated into larger Asgaard, U. and Bromley, R. G. 1974: Sporfossiler fra den groups. The larger groups are typically well mellem miocæne transgression i Søby-Fasterholt området. Dansk geol. Foren., Årsskrift for 1973: 11-19. organized, and may be regarded as some kind of Baltes, N. 1969: Distribution stratigraphique des dinoflagellés colonial structure in which the individuals are et des acritarches tertiaires en Roumanie. In Brönnimann, arranged in a double layered plate comprising up P. and Renz, H. H., eds.: Proceedings First International Conference Planktonic Microfossils, Geneva 1967, vol. 1: to 30 individuals. The surface of the individuals 26-45. bear only spines in the areas which are not in Benedek, P. N. 1972: Phytoplanktonten aus dem Mittel- und contact with another individual. The area covered Oberoligozän von Tönisberg (Niederrheingebiet). Palaeontographica, Abt. B, 137: 1-71. with spines seems to vary in size on single indi­ Brosius, M. 1963: Plankton aus dem nordhessischen Kasseler viduals. When the aperture is visible, it is always Meeressand (Oberoligozän). Deutsch. Geol. Gesell, situated in the area covered with spines. Zeitsch., 114: 32-56. Buchardt, B. 1978: Oxygène isotope palaeotemperatures from the Tertiary period in the North Sea area. Nature 275: 121-123. Chene, R. J. du 1977: Étude palynologique du Miocène Supérieur Andalou (Espagne). Revista Espanola de Mic- ropal. IX: 97-114. - Acknowledgements. The author wishes to thank B. Håkansson Cookson, I. C. and Eisenack, A. 1968: Microplankton from two for long and helpful discussions, and R. Harland and H. Gocht samples from Gingin Brook No. 4 Borehole, Western Au- for valuable criticism. The Geological Central Institute, Uni­ straUa. Aoya/Soc. Western Australia Jour. 51: 110-122. versity of Copenhagen, is thanked for permission to use the Cookson, I. C. & Eisenack, A. 1974: Mikroplankton aus au­ facilities and the scanning electron microscopes of the Labora­ stralischen mesozoischen und tertiären Sedimenten. tory of Electron Microscopy. Diana Bathurst kindly improved Palaeontographica, Abt. B 148: 44-93. the English text and H. Egelund made the drawings. The study Dale, B. 1976: Cyst formation, sedimentation and preserva­ was supported by the Danish Natural Science Research Found­ tion: factors affecting dinoflagellate assemblages in Recent ation. sediments from TrondheimsÇord, Norway. Rev. Palaeobot. Palynol. 22: 39-60. Davey, .R. J.; and I Williams, ; G. L.l l966£)The; genusi.Hyim- chosphaeridium and its allies. In: Davey, R. J., Downie, C, Sarjeant, W. A. S. and Williams, G. L.: Studies on Mesozoic and Cainozoic dinoflagellate cysts. Bull. Brit. Mus. (Nat. Hist.) Geol., Supp. 3: 1-248. Bulletin of the Geological Society of Denmark, vol. 29 1980 75

Davey, R. J., Downie, C, Sarjeant, W. A. S. and Williams, G. Kristoffersen, F. N. 1972: Foraminiferzonering i det jyske L. 1969: Appendix to "Studies on Mesozoic and Cainozoic Miocæn. Dansk geol Foren., Årsskrift for 1971: 79-85. dindflagellate cysts". Bull. Brit. Mus. (Nat. Hist.) GeoL, Krutzsch, W. 1959: Mikropaläontologische (sporenpaläon- Appendix to Supp. 3, 1-17. tologische) Untersuchungen in der Braunkohle des Gei- Deflandre, G. and Cookson, I. C. 1955: Fossil microplankton seltales. Geologie 8, 21-22: 1^25. from AustraUan Late Mesozoic and Tertiary sediments. Lentin, J. K. and WiUiams, G. L. 1976; A monograph of fossil Australian Jour. Marine and Freshwater Research 6: peridinoid dinoflagellate cysts. Bedford Inst. 242-313. Oceanography Rept. BI-R-75-16; 1-237. Downie, C, Hussain, M. A. & WiUiams, G. L. 1971: Dino- Maier, D. 1959: Planktonuntersuchungen in tertiären und ilagellate cysts and acritarch association in the Palaeogene quartären marinen Sedimenten. N. Jb. Geol. Paläont., of Southeast England. Geoscience and Man 3: 29-35. Abh. 107: 278-340. Drugg, W. S. 1970: Two new Neogene species of Tuber- Manum, S. B. 1976: Dinocrysts in Tertiary Norwegian-Green­ culodinium and one olXenicodinium (Pyrrhophyta). Biol land Sea sediments (Deep Sea Drilling Project Leg 38), Soc. Washington Proc. 83: 115-121. with observation's on palynomorphs and palynodebris in Drugg, W. S. and Lx)eblich, A. R. jr. 1967: Some Eocene and relation to environment. In Talwani, M., Udintsev, G. et Oligocène phytoplankton from the Gulf Coast, U.S.A. al. 1976. Initial Reports of the Deep Sea Drilling Project Tulane Studies Geology 5: 181-194. 38; 897-919. Eaton, G. L. 1976: Dinoflagellate cysts from the Bracklesham Morgenroth, P. 1966: Mikrofossilien und Konkretionen des Beds (Eocene) of the Isle of Wight, Southern England. nordwesteuropäischen Untereocäns. Palaeonlographica, Bull. Brit. Mus. (Nat. Hist) Geol. 26: 277-332. Abt. B, 119; 1-53. Eisenack, A. 1954; Miktofossilien aus Phosphoriten des sam- Rasmussen, L. B. 1956: The marine Upper Miocene of South landischen Unteroligozäns und über die Einheiüichkeit Jutland and its molluscan fauna. Danm. Geol. Unders. II der Hystrichosphaerideen. Palaeonlographica, Abt. A, rk., 81; 166 pp. 105: 49-95. Rasmussen, L. B. 1961; De Miocæne Formationer i Danmark. Eisenack, A. 1958: Mikroplankton aus dem norddeutschen Apt Danm. Geol. Unders. IV rk., 4 (5): 45 pp. nebst einigen Bemerkungen über fossile Dinoflagellaten. Rasmussen, L. B. 1966: Biostratigraphical studies on the N. Jb. Geol. Paläont., Abh. 106: 383^22. marine younger Miocene of Denmark. Based on mollus­ Bisgaard, G., Fine, S., Fredericia, J., Holm, L., Larson, K. & can faunas. Geol Surv. Denm., II series, 88: 358 pp. Nygaard, E. 1977; Rapport over undersøgelser af de Rasmussen, L. B. 1974: Some geological results from the first miocœne lag gennemboret ved Gram. Unpublished report. five exploration wells in the North Sea. Geol. Surv. Denm., Geologicai Museum, University of Copenhagen. (In Ill Series, 42: 46 pp. Danish). Reid, P. C, 1974: Gonyaulacacean dinoflagellate cysts from Evitt, W. R: 1976; The Pyrodinium tabulation as a pattern of the British Isles. Nova Hedwigia 25: 579-637. major importance in fossil dinoflagellates. Abstract, Di­ Reid, P. C, 1977: Peridiniacean and Glenodiniacean dino­ noflagellate Conference, Oslo, 11-13. Aug., 1976. flagellate cysts from the British Isles. Nova Hedwigia 28. Evitt, W. R., Lentin, J. K., Millioud, M. E., Stover, L. E. & Rossignol, M. 1962; Analyse poUinique de sédiments marins WilUams, G. L. 1977: Dinoflagellate cyst terminology. Quaternaires en Israël. II. Sédiments Pleistocenes. Pollen Geol. Surv. Can. Paper 76-24: 1-11. et Spores 4: 121-148. Gerlach, E. 1961; Mikrofossilien aus dem Oligozän und Sarjeant, W. A. S. 1970: The genus Spiniferites Mantell 1850 Miozän Nordwestdeutschlands, unter besonderer Be­ (Dinophyceae). Grana 10: 74-78. rücksichtigung der Hystrichosphaerideen und Dinoflagel­ Sorgenfrei, Th. 1940; Marint Nedre-Miocæn i Klintingehoved laten. N. Jb. Geol. Paläont., Abh. 112; 143-228. på Als. Danm. Geol. Unders. II rk. 65: 143 pp. Gocht, H. 1975: Neuuntersuchung von Eodinia pachytheca Sorgen&ei, Th. 1958; Molluscan assemblages from the marine Eisenack 1936 (Dinoflagellata, Oberjura). N. Jb. Geol. Middle Miocene of South Jutland and their environments. Paläont., Abh. 148; 12-32. Danm. Geol. Unders. II rk. 79 (I-II): 502 pp. Habib, D. 1972: Dinoflagellate stratigraphy Leg 11, Deep Sea Stover, L. E. and Evitt, R. E. 1978: Analyses of Pre-Pleis- Drilling Project. In: HoIIister, C. D., Erwing, J. I. et al., toccne organic-walled dinoflagellates. Stanford University Inü'ml reports of the Deep Sea Drilling Project. XI: Publications, Geological Science XV; 300 pp. 367-425. Talwani, M., Udintsev, G. et al. 1976; Initial Reports of the Hansen, i. M. 1977; Dinoflagellate stratigraphy and echinoid Deep Sea Drilling Project, Vol. 38, Washington (U. S. distribution in Upper Maastrichtian and Danian deposits Government Printing Office), 1256 pp. from Denmark. Bull geol Soc. Denmark 26: 1-26. Wall, D. 1967: Fossil microplankton in deep-sea cores from the Harland, R. 1977: Recent and Late Quaternary (Flandrian and Caribbean Sea. Palaeontology 10: 95-123. Devensian) dinoflagellate cysts from marine continental Wall, D. and Dale, B. 1969: The "hystrichosphaerid" resting shelf sediments around the British Isles. Palaeonlogra­ spore of the dinoflagellate Pyrodinium bahamense Plate, phica, Abt. B, 164; 87-126. 1906./. Phycol. 5; 140-149. Harland, R. 1978: Quaternary and Neogene dinoflagellate Wall, D., Dale, B. and Harada, K. 1973: Descriptions of new cysts. In: B. Thusu (ed.): Distribution of biostratigraphic- fossil dinoflagellates from the Late Quaternary of the ally diagnostic dinoflagellate cysts and miospores from the Black Sea. Micropaleontology 19; 18-31. Northwest European continental shelf and adjacent areas. Wall, D., Dale, B., Lohmann, G. P. & Smith, W. K. 1977; The Continental Shelf Inst. Publ. 100: 7-17. environmental and climatic distribution of dinoflagellate Klumpp, B. 1953; Beitrag zur Kenntnis der Mikrofossilien des cysts in modern marine sediments from regions in the mittleren und oberen Eozän. Palaeonlographica, Abt. A, North and South Atlantic Oceans and adjacent seas. 103; 337-406. Marine Micropataeontology, 2: 121—200. Koch, B. E., Friedrich, W. L., Christensen, E. F. and Friis, E. Van Geel, B. 1976: Fossil spores of Zygnemataceae in the M. 1973: Den miocæne brunkulsflora og dens geologiske ditches of a prehistoric settlement in Hoogkarspel (The miljø i Søby-Fasterhoh området sydøst for Herning. Netheriands). Rev. Palaeobot. Palynol. 22; 337-344. Dansk geol Foren. Årsskrift for 1972: 1-57. Van Geel, B. 1978: A palaeoecological study of Holocene peat Koch, B. E. 1975: Træk af brunkulsbrydningens historie i bog sections in Germany and the Netherlands, based on Danmark. Museerne i Viborg Amt. 5: 1—18. the analysis of pollen, spores and macro- and microscopic 76 Piasecki: Miocene stratigraphy

remains of fungi, algae, cormophytes and animals. Rev. Williams, G. L. and Brideaux, W. W. 1975: Palynologie Paleobot. Palynol. 25: 1-120. analysis of Upper Mesozoic and Cenozoic rocks of the Van Geel, B. and Van der Hammen, T. 1978: Zygnematacea in Grand Banks, Atlantic continental margin. Geological Quaternary Colombian sediments. Rev. Palaeobot. Survey of Canada, Bull. 236: 162 pp. Palynol. 25: 377-392. Wilson, G. J. 1973: Palynology of the middle Pleistocene Te Williams, D. B. 1971: The occurrence of dinoflagellates in Piki bed, Cape Runaway, New Zealand. New Zealand marine sediments. In: Funnel, B. M. and Riedel, W. R. Jour. Geology and Geophysics 16: 345-354. (eds): Micropalaeontology of Oceans, C.U.P. Cambridge. 231-243.