Environmental changes reflected by palynomorphs in the early Middle Ordovician Hanadir Member of the Qasim Formation, Saudi Arabia

Core samples from the QASIM-801 (QSIM-801) water well in the Qasim Region of central Saudi Arabia were investigated palynologically. The interval studied contains the transgressive succession from the Sajir Member of the Saq Formation to the Hanadir Member of the Qasim Formation, and yields well-preserved and abundant cryptospores, microphytoplankton (acritarchs and chlorophycean algae), and chitinozoans, indicative of a Darriwilian (Llanvirn) age. The lowermost portion of the cored interval from the upper Sajir Member consists of fine-grained sandstones deposited in tidal flat, and shallow-marine settings. It is characterized by abundant and diverse cryptospores (permanent tetrads, dyads, monads), cuticle-like phytoclasts, and a low diversity assemblage of marine palynomorphs. The upper part of the cored interval from the Hanadir Member is composed of hemipelagic to pelagic, organic-rich, graptolitic shales, and micaceous shales, of middle- to outer-shelf depositional settings, which yield abundant marine palynomorphs (acritarchs and chitinozoans). Cryptospore-bearing horizons are interspersed in the succession. Changes in the composition of palynomorph assemblages reflect higher frequency environmental changes within an overall transgressive succession. Four new acritarch species are described in open nomenclature, Tyrannus sp. A, Clypeolus sp. A,?Pulvinosphaeridium sp. A, and?Tinacula sp. A.     

Acritarchs from the Dadas Formationin Southeast Turkey

Dadas Formation in Southeast Turkey yields abundant well preserved acritarchs, chitinozoans, tasmanites and scolecodonts. Encountered acritarchs suggest Upper Llandoverian-Ludlovian age for this formation. The acritarch association of the Dadas Formation resembles to the Middle Silurian assemblages of Tunisia and Libya. Thus Southeast Turkey falls in the Transitional-Iberian realm of Neoveryhachium carminae facies.     

Upper Ordovician microphytoplankton of the Bill's Creek Shale and Stonington Formation,Upper Peninsula of Michigan,U.S.A.: Biostratigraphy and paleogeographic significance

An abundant, diverse, and well-preserved organic-walled microphytoplankton assemblage is described from the Upper Ordovician Bill's Creek Shale and the lower Stonington Formation (Bay de Noc Member) in the Upper Peninsula of Michigan, U.S.A. Based on graptolite and conodont evidence, the Bill's Creek Shale and Stonington Formation are Richmondian (=Ashgill) in age. The assemblage is dominated by acritarchs, which comprise 29 species (including the enigmatic palynomorph Gloeocapsomorpha prisca) assigned to 20 genera. The prasinophyte phycomata are represented by undifferentiated species of Leiosphaeridia and Tasmanites. In addition, chitinozoans are abundant, and scolecodonts and graptolite fragments are common. Paleontologic-palynologic and sedimentologic evidence indicates that the Bill's Creek Shale was deposited in a low-energy, shallow, nearshore marine environment. The overlying Bay de Noc Member of the Stonington Formation also accumulated in a low-energy, normal marine environment, but in a more offshore, somewhat deeper water setting. Both formations experienced minor transgressive and regressive episodes as indicated by fluctuations in the composition of the palynoflora. The combined Bill's Creek/Stonington acritarch assemblage closely resembles those described from the Richmondian-aged Maquoketa Shale (Missouri and Kansas), Sylvan Shale (Oklahoma), and Vauréal Formation (Anticosti Island, Québec, Canada). The overall composition of the acritarch assemblage from these four formations reflects a distinctive, recognizably Laurentian character. Nonetheless, many of the Bill's Creek/Stonington acritarchs have been reported from Upper Ordovician localities elsewhere, providing additional evidence for Late Ordovician cosmopolitanism of the marine microphytoplankton community. Additionally, the restricted stratigraphic range of many of the taxa further enhances their biostratigraphic application, both regionally and globally, and reaffirms the Richmondian (=Ashgill) age of the Bill's Creek Shale and Stonington Formation.     

Integrated Middle Devonian chitinozoan and miospore zonation of the Amazonas Basin, northern Brazil

Middle Devonian chitinozoans were studied from 13 deep wells in the central part of the Amazonas Basin, northern Brazil, and compared with a newly established regional miospore zonation. Of the 23 chitinozoan species encountered, four are newly described: Ancyrochitina multibrachiata, Lagenochitina praeavelinoi, Ramochitina autasmirimense, and Ramochitina herculesi and seven species are retained in open nomenclature because of an insufficient number of well-preserved specimens. The stratigraphic intervals investigated herein correspond to three miospore interval range zones previously defined for the Amazonas Basin, namely, the Grandispora/Samarisporites spp. (GS); late Emsian-early Eifelian, Grandispora permulta (Per); late early Eifelian through the Eifelian-Givetian transition, and Geminospora lemurata-Chelinospora ex. gr. ligurata (LLi); early Givetian. A regional Middle Devonian chitinozoan biozonation, also consisting of three zones, is proposed for the investigated interval. These zones are the interval zone of Angochitina n. sp. A (early Eifelian), the interval zone of Alpenachitina eisenacki (late early to late Eifelian), and the total range zone of Ramochitina stiphrospinata (early Givetian).     

Paleoecology,biostratigraphy and biogeography of late Silurian to early Devonian acritarchs and prasinophycean phycomata in well A161, Western Libya,North Africa

Diverse and well preserved acritarch and prasinophycean phycomata assemblages were recovered from the late Silurian to Lower Devonian strata of well A161 in western Libya, and four distinct acritarch biozones are recognized, based on the stratigraphic distribution of 156 species. The palynoflora is independently dated by means of chitinozoans, and allows discussion of the evolution of acritarchs and prasinophyte phycomata across the Ludlow–Přı́dolı́ boundary in relation to probable major climatic change, as well as in the early and middle Přı́dolı́, and the lower Lochkovian. Correlations are proposed with the British Isles, Baltica, and Algerian Sahara. Sedimentation occurred in shallow high-energy conditions throughout, but with periodic rise of sea level. The changes in marine to terrestrial palynomorph ratios through the section document the relationship between marine palynomorph assemblages and sea surface conditions in these marginal marine environments. The major drift of Gondwana towards low latitudes during the Ludlow–Přı́dolı́ transition seems to have been the driving force behind homogenization of assemblages on the two sides of the Rheic ocean, and explains the similarities between phytoplanktonic assemblages of the north Gondwanan margin and the South of Baltica. The data suggest that the Rheic ocean was almost closed by the late Silurian, and had become restricted to a moderately deep sea. In the Lochkovian the microflora are strongly facies-dependent and delineate more restricted provinces such as the Ibarmaghian domain in the sense of Plusquellec (1987) including the Maghreb and Ibero–Armorican areas.Nine new species are described: Arkonia nova, Arkonia paulumstriata, ?Cymatiosphaera florida, Cymatiosphaera nimia, Dactylofusa hispidusa, Disparifusa quasibernesgae, Evittia areolata, Multiplicisphaeridium verticisum, and ?Villosacapsula steemansii. In addition, three new combinations are suggested: Visbysphaera bonita (Cramer) comb. nov., Visbysphaera jardinei (Cramer) comb. nov. and Visbysphaera albanega (Cramer et al.) comb. nov.     

Biodiversity patterns of Early–Middle Ordovician marine microphytoplankton in South China

Based on new materials from six sections and all available literature data, new diversity curves are presented for the phytoplankton (acritarchs) from South China, covering the Early–Middle Ordovician interval, when the Great Ordovician Biodiversification Event took place. The total diversity curve and the origination data imply that a major radiation of the phytoplankton occurred during the analysed interval. A peak of the total acritarch diversity curve appears in the A. suecicus graptolite biozone. The diversity changes vary in the different parts of the investigated area, most probably depending on the position of the analysed sections on the carbonate shelf or the slope, reflecting diversity differences due to the position on an inshore–offshore transect.The Early–Middle Ordovician diversity pattern of the phytoplankton is compared with those of several marine invertebrate groups. Compared with the diversity curve peak of the acritarchs, the conodonts and brachiopods reached their highest diversities before the acritarchs, while the highest diversity of the chitinozoans appears slightly later. The graptolites show two peaks during the Early–Middle Ordovician, while the trilobites diversity curve shows a peak only in the Sandbian. The different fossil groups, such as chitinozoans, conodonts, graptolites, brachiopods and trilobites show therefore different evolutionary patterns to that of the acritarchs, that are not yet fully understood, and correlations are so far difficult.The acritarch diversity changes can partly be compared to the local sea-level changes from four sections in South China. At a larger scale, the acritarch radiation coincides with a general transgression. At a regional or local scale, correlations are not straightforward, pointing out that more detailed data, based on both acritarch studies and more precise sea-level investigations, are necessary.     

Late Devonian Acritarchs from the Gneudna formation in the Western Carnarvon basin,Western Australia

The Gneudna Formation is a Late Devonian(Frasnian) sequence of marine calcareous sediments that occurs in the Carnarvon Basin, Western Australia. The present palynological study is based upon subsurface silty strata from a borehole (Pelican Hill or Bibbawarra Bore) that was drilled early this century near the western coastal limit of the Carnarvon Basin.The subject strata have previously been attributed to the Gneudna Formation on lithostratigraphic grounds. They contain a rich and varied assemblage of marine microphytoplankton (acritarchs), associated with trilete miospores of which Geminospora lemurataBalme, 1962 is the dominant form. Forty-seven species of acritarchs are recognizable in the palynoflora, which corresponds very closely with that described recently (Playford & Dring, 1981) from the Gneudna Formation in the vicinity of its type section on the opposite (eastern) side of the Carnarvon Basin. The apparently parochial complexion of the Gneudna acritarch suite is probably illusory, insofar as early Late Devonian acritarchs have not been studied extensively or intensively from either the northern or southern hemispheres.The following new species of acritarchs areformally instituted herein: Elektoriskos villosa, Lophosphaeridium pelicanensis, and Pterospermella tenellula.     

Palynostratigraphy and palaeogeography of the Padeha, Khoshyeilagh, and Mobarak formations in the eastern Alborz Range (Kopet-Dagh region), northeastern Iran

A total of 113 surface samples collected from the Padeha, Khoshyeilagh, and Mobarak formations of Kuh-e-Ozum, northeast of Jajarm town were processed for palynomorphs, in order to determine age relationships. Well-preserved and abundant palynomorphs dominated by organic-walled-marine microphytoplankton (acritarchs and prasinophyte phycomata), miospores and subordinate chitinozoans, and scolecodonts were recovered. Seven species of prasinophyte phycomata (four genera), 19 acritarch species (14 genera), one species of chitinozoa, and 26 miospore species (19 genera) were recorded and assigned to eight local Assemblage Zones. Assemblage Zones I-IV occur in the Padeha Formation and suggest an Early Late Devonian (Frasnian) age whilst assemblages zones V-VII are present in the Khoshyeilagh Formation and indicate Late Devonian (Famennian) ages. Assemblage zone VIII, which occurs in the basal part of Mobarak Formation, suggests a Lower Mississippian (Tournaisian) age for this formation. Many of the palynomorph groups encountered are closely comparable with coeval assemblages recorded from Western Australia, southwest Ireland, England, Turkey, Saudi Arabia, North Africa, and South America, indicating the close relationship of the Iranian Platform to other parts of the northern Gondwana Domain during the time interval represented by these strata. The presence of marine palynomorphs (acritarchs/prasinophyte phycomata, chitinozoans, and scolecodonts), and shelly macrofauna (brachiopods, gastropods, and corals) in Member c of the Padeha Formation (as well as the Khoshyeilagh and Mobarak formations), together with associated miospores, indicate an open marine (moderately nearshore) depositional environment for the Upper Devonian and Lower Carboniferous deposits in northeastern Alborz Range (Kopet-Dagh region) of Iran.     

Ordovician chitinozoans and acritarchs from southern and southeastern Turkey

Revision of the lithostratigraphy of Ordovician deposits in southern and southeastern Turkey led to a re-evaluation of the age assignments of formations identified in the subsurface and at outcrop. Previous datings were based on macrofauna (mainly trilobites and graptolites). The present paper focuses exclusively on organic-walled microfossils (chitinozoans and acritarchs), which provide numerous chronostratigraphical improvements, especially in successions barren or poor in macrofossils. Close to 200 samples were collected in the Taurus chain (i.e. from Kemer, Seydisehir, Ovacik, Kozan, to Sariz regions in southern Turkey) and in the Border Folds (Mardin and Hakkari regions), usually regarded as part of the Arabian Plate in palaeogeographical reconstructions. Many samples are productive and yield chitinozoans and/or acritarchs of extremely variable preservation, depending on their geographical and geological location. In the Taurus chain, the material is “coalified” and frequently fragmented whereas, in the Border Folds, maturation of the organic matter is much lower and preservation of the microfossils is good to excellent. Several Ordovician chitinozoan biozones (northern Gondwana zonation) as well as diagnostic acritarch assemblages are identified in southern and southeastern Turkey. These Ordovician formations are assigned here to the new global stages of the Ordovician chronostratigraphical scale. The Seydisehir (upper part), Sobova, and Kilgen Lake (lower part) formations are referred to the Darriwilian. The Kilgen Lake (upper part), Sort Tepe, and Bedinan formations are attributed to the Sandbian and to the Katian, and the Halevikdere Formation (glacio-marine part) is assigned to the Hirnantian. Reworking of Early Ordovician acritarchs is documented in pre-glacial and in glacial Late Ordovician deposits. They indicate that active erosive processes occurred during the Middle and Late Ordovician sedimentation. The organic-walled microfossils recorded in the Ordovician of south and southeastern Turkey belong to the northern Gondwana realm. Interestingly however, some Baltoscandian influences are noted in the Border Folds during Early Late Ordovician.     

Carnivores from the early/middle Miocene locality of Antonios (Chalkidiki, Macedonia, Greece)

The mammal locality of Antonios is one of the few known early-middle Miocene ones of Greece with large mammals. It is situated in Chalkidiki Peninsula (Macedonia, Greece) and includes both small and large mammals. The study of the carnivores found in Antonios indicates the presence of the following taxa: Proputorius cf. P. sansaniensis, Protictitherium gaillardi, Protictitherium cf. P. crassum, Percrocuta sp., Percrocutidae indet. and Pseusaelurus romieviensis. The material of each taxon is described, compared with other material from various Eurasian localities and determined. The species P. cf. sansaniensis and P. romieviensis are traced for first time in Eastern Mediterranean, while Percrocuta for first time in Greece. The presence of the other carnivoran taxa in the Antonios fauna is also interesting as they are recognized in older stratigraphic levels enriching our knowledge about their stratigraphic distribution. The carnivores of Antonios cannot offer significant data for the dating of the fauna but its age is discussed using the data coming from the carnivores as well as those from older studies of the micromammals and suoids.     

Lower Bashkirian conodonts from the Iraty Formation in the Alduides-Quinto Real Massif (Pyrenees,Spain)

The stratigraphy of the Carboniferous Iraty Formation is described in several sections from the southwestern Alduides-Quinto Real Massif (western Pyrenees), and biostratigraphy is updated based on conodont occurrences. The Ochaverri Member yields upper Serpukhovian conodonts, whereas the lower part of the overlying Asturreta Member is assigned to the lower Bashkirian, according to the occurrences of Declinognathodus noduliferus bernesgae and D. n. noduliferus, respectively. The upper beds of the formation (Baserdi Member) are correlated with the Kinderscoutian to lowermost Marsdenian English substages (lower Bashkirian), and new conodont occurrences are the oldest species of Neognathodus and Idiognathodus known in Spain. We discuss the status of Idiognathoides macer, several species related to I. sinuatus, I. sulcatus and Lochriea glaber. Conodont diversity is related to stratigraphic distribution of species and conodont biofacies. Finally, the lowermost Marsdenian to upper Bashkirian age of the siliciclastic rocks overlying the Iraty Formation is also discussed and compared with known data from localities in the western Pyrenees.     

Siluro-Devonian miospore biostratigraphy of the Urubu River area, western Amazon Basin, northern Brazil

Well-preserved miospores have been observed in the Urubu River area from the western part of the Amazon Basin, northern Brazil, in rocks belonging to the uppermost Pitinga and Manacapuru Formations. A previous palynological work based on chitinozoans has dated these strata as Late Ludlow, Early Pridoli and Early Lochkovian. Although samples are relatively poor in miospores, the present study reveals the most diversified Silurian-Earliest Lochkovian palynoflora ever reported from South America, an interval where miospore information is still very rare. Sixty-four species have been identified, of which two are new (Artemopyra urubuense and Retusotriletes amazonensis). One single specimen attributed to the genus Grandispora, identical to unpublished forms identified by one of us (P.S.) in Lochkovian sections of Saudi Arabia, has been found in a Lochkovian sample from the Urubu River. These constitute the oldest geological record of Grandispora. Among the abundant acritarchs, specimens of the genus Schizocystia have been observed for the first time in pre-Devonian rocks.Although the Late Silurian-Early Lochkovian miospore biostratigraphy is still in its infancy in South America, it seems that Amazon Basin assemblages do not show significant differences in composition in comparison to coeval palynofloras from other areas of northwestern Gondwana. This is surprising since the miospore localities under consideration are widely distributed over high to low paleolatitudes, i.e. from cool temperate to dry subtropical belts. Conversely, Siluro-Devonian Gondwanan assemblages differ considerably from the contemporary palynofloras of the Old Red Sandstone Continent and adjacent areas, thus contradicting recent phytogeographic interpretations based on megafloras.     

Middle–Late Ordovician chitinozoans from Songliang of Qiaojia,western South China,and their biostratigraphic implications

Ordovician chitinozoans are as yet inadequately documented from the western Yangtze Platform, South China. Here we present a systematic study on chitinozoans from a Middle–Upper Ordovician succession at Songliang of Qiaojia, northestern Yunnan, southwestern China. Altogether 34 species of 12 genera are identified from the upper Hungshihyen and the Huadan formations. The top of the Hungshihyen Formation yields typical Early and Middle Ordovician forms, for instance, Lagenochitina obeligis and Belonechitina chenjiawuensis, with the latter only known from the lower Darriwilian in South China, thus suggesting an early Darriwilian age for this interval. The chitinozoans recovered from the Huadan Formation include Lagenochitina prussica and Spinachitina fossensis, both are mainly confined in Katian and sometimes ranging into younger strata. This indicates an age younger than the middle to late Darriwilian previously determined for the Huadan Formation. However, conflicts exist in age assignment of the Huadan Formation based on chitinozoan and other evidence, and further work is required.     

Infrared video microscopy—an efficient-method for the routine investigation of opaque organic-walled microfossils

Summary Dark or even opaque organic-walled microfossils are frequently represented in palynological residues which are derived from sediments of high maturity. Such particles may be studied surficially by SEM or incident light, but internal details remain obscured. It has been known for some time that transparency may be achieved by applying infrared microscopy, but the method never became routine. We have now assembled an IR equipment which is based on a regular transmitted light microscope and tested our setup on various kinds of palyno-morphse.g. spores, acritarchs, chitinozoans, scolecodonts as well as phytoclasts and zooclasts. Our examples are from several localities of different stratigraphic and palaeogeographic position within the Palaeozoic. The studies revealed a high potential for IR video microscopy to become an important tool in the study of thermally altered organic particles in palynological slides.     

Miospore stratigraphy of Lower and early Middle Devonian deposits from Tidikelt, Central Sahara, Algeria

The Tidikelt region forms an outstanding area for subsurface Lower Devonian stratigraphy in the central Algerian Sahara. Sediments from five boreholes have revealed abundant and diverse assemblages of miospores, acritarchs, chitinozoa, scolecodont and microplant remains. The miospores are moderately well preserved. Three new miospore species (Dibolisporites saharansis nov. sp. Hassan Kermandji, Acinosporites conatus nov. sp. Hassan Kermandji and Scylaspora tidikeltense nov. sp. Hassan Kermandji) are described. Miospore assemblages vary through the regressive and transgressive sequences. Seven miospore assemblage biozones, including six new miospore assemblage biozones (Scylaspora tidikeltense-Perotrilites microbaculatus, Dictyotriletes emsiensis-Emphanisporites spinaeformis, Apiculiretusispora arenorugosa-Camptozonotriletes caperatus, Verrucosisporites polygonalis-Dictyotriletes subgranifer, Emphanisporites annulatus-Geminospora svalbardiae, Hystricosporites microancyreus-Grandispora protea, Calyptosporites velatus-Rhabdosporites langii) are proposed for the Lower and early Middle Devonian rocks of Tidikelt Plateau. The combined use of distinctive, wide distribution cosmopolitan and Gondwanan forms as biozonal and species characteristics permits accurate subdivision, dating and correlation of Tidikelt successions with other similar miospore zones of the Lower Devonian of Europe, Canada and other parts of Gondwana plate. The miospore data provide new explanations to stratigraphic relationships of regional rock units, sedimentary cycles and stratigraphic hiatus. The miospore biozones are proposed as a provincial biozonation, which may also be applied to other Palaeozoic rocks of similar miospore content.     

Late Messinian rodents from Verduno (Piedmont,NW Italy): Biochronological,paleoecological and paleobiogeographic implications

The stratigraphic and paleoenvironmental context of the Verduno fossil vertebrate locality is discussed herein based on its rodent record. The Verduno section crops out in the southern part of the Tertiary Piedmont Basin (TPB), and can be included in the Messinian post-evaporitic Cassano Spinola Fm., chronologically corresponding to the so-called Lago-Mare event. Rodents are represented by a relatively rich assemblage. Murids are by far the most diverse and abundant, with at least four taxa, including the common Centralomys benericettii and Paraethomys meini, and the rare Apodemus gudrunae and Occitanomys sp. Cricetids are represented by a single species, Apocricetus cf. A. barrierei. Muscardinus aff. M. vireti appears to be the only glirid present at Verduno. The Verduno rodent assemblage shares some taxa with other Messinian post-evaporitic localities from Italy bearing continental vertebrate remains, such as Brisighella (central Italy) and Moncucco Torinese (NW Italy) (e.g., C. benericettii, P. meini) and, possibly, with Ciabòt Cagna (NW Italy). However, the general structure of these four Messinian assemblages displays substantial differences, which may reflect different palaeoenvironmental conditions.     

Intraspecific variation in Triassic Ophthalmidiid Foraminifera from Timor

Four ophthalmidiid species are described as free specimens extracted from mudstones and wackestones of Triassic age: Atsabella bandeiraensis nov. gen. nov. sp., Karaburunia atsabensis nov. sp., Ophthalmidium sp. cf. O. primitivum Ho and Spirophthalmidium grunaui nov. sp. Analysis of morphological variation found in large suites of specimens suggests that, as in modern miliolids, apertural characteristics, chamber shape and adult test size are features that vary within narrow limits and may be used to define species. In genera with milioline coiling in the post-embryonic stage, chamber arrangement may be highly variable. Post-embryonic coiling in K. atsabensis varies from quinqueloculine to almost spiroloculine and encompasses morphotypes that, in thin-section studies, have been attributed to a number of other genera. In Timor Leste, A. bandeiraensis, K. atsabensis and S. grunaui have been found with conodonts indicative of the Carnian, but the full local stratigraphic range of these species is uncertain. K. atsabensis occurs at another locality with conodonts suggestive of the Middle Triassic or less likely Carnian. Ophthalmidium sp. cf. O. primitivum has been found at one locality associated with A. bandeiraensis and K. atsabensis in a stratigraphic succession that suggests a correlation to the Carnian or Norian. The ophthalmidiids are found commonly associated with organic-cemented agglutinated and hyaline foraminifera and at some localities common to abundant ostracods and mollusc debris. They were most common in organic-rich carbonate mud of shallow-marine environments.     

Middle-upper Eocene ostracods and nummulites from Gebel Na’alun, southeastern Fayum, Egypt

The middle-upper Eocene sequence at Gebel Na’alun, southeastern Fayum yielded 21 ostracod and four nummulite species. Out of these, two new ostracod species namely Bairdia crolifai and Paracypris naalunensis are described. Four ostracod assemblages are distinguishable; the lower three are assigned to the Bartonian and the upper one is Priabonian. The nummulites exist in three stratigraphic horizons represented from base to top by “Nummulites” aff. pulchellus, Nummulites decrouezae with Nummulites cavelieri (Bartonian) and Nummulites aff. fabianii (Priabonian).