Radiizonates arcuatus, a distinctive new miospore species from the Lower Carboniferous of Western Gondwana

A new species of trilete zonate miospores, Radiizonates arcuatus, is established for Lower Carboniferous Western Gondwanan forms hitherto ascribed misguidedly to Radiizonates genuinus (Jushko) Loboziak and Alpern (1978), a Russian Lower Carboniferous species. The latter binomen is, moreover, not a valid combination and is more correctly designated as Vallatisporites genuinus (Jushko) Byvsheva, 1980. R. arcuatus is, from records to date, confined to westerly parts of Gondwana (Brazil, North Africa and Middle East), in which it is characteristic of Early Carboniferous strata, albeit with some slightly older and slightly younger occurrences.     

Devonian spore assemblages of China

Data available show that there are many genera and species of Devonian spores in China (together with acritarchs, chitinozoans and scolecodonts) which are commonly well-preserved, especially in South China where they are also better studied. This permits their use for correlation in detailed stratigraphical studies.On the basis of the study on Devonian spores for the past twenty years it is suggested that eight Devonian spore assemblage zones may be recognised in China, with four zones for the Lower Devonian, two zones for the Middle Devonian and two zones for the Upper Devonian. Each zone is characterised by a distinctive suite of miospores.The spore assemblages of China may be correlated basically with those in Great Britain, Federal Germany, Spitsbergen, U.S.S.R., and North America.     

Aratrisporites saharaensis sp. nov.: A characteristic lower carboniferous miospore species of North Africa

A new miospore species Aratrisporites saharaensis is described. Attributed to a genus previously known mainly from the Trias, it constitutes the first record of monolete camerate miospores from the Carboniferous.This taxon occurs abundantly in the Lower Carboniferousof northern region of the Sahara, North Africa. It has, in the past, been incorrectly attributed by several authors to Spelaeotriletes balteatus (Playford) Higgs 1975. Its stratigraphic range is late Tournaisian to early Namurian.     

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.     

Diversity of exine structure in Upper Carboniferous (Westphalian) selaginellalean megaspores

Studies of wall structure in Mesozoic and Recent selaginellalean megaspores have been well documented. However, Palaeozoic examples have received minimal attention. The principal Palaeozoic megaspore genus of likely selaginellalean affinity is Triangulatisporites, extending from the Upper Devonian to the Upper Carboniferous. The particulate wall ultrastructure of a previously published Carboniferous (Duckmantian) megaspore assigned to this genus suggested that this form of wall construction may have been the ancestral wall structure of the group, an observation which posed difficulties in relating selaginellalean ultrastructure to that of other contemporaneous lycopsid megaspores. Subsequent investigation showed that the genus also contains more laminate exines similar to those of other extinct lycopsids and extant Selaginella species. Our new examples of Triangulatisporites ultrastructure from the Langsettian, Duckmantian and Westphalian D yield more information regarding early variation of wall structure within Carboniferous selaginellalean megaspores and suggest that a more laminate wall composition is at least as old as the particulate form. However, without further investigation of Lower Carboniferous forms, we are unable to state which is indeed ancestral. The laminate structure reported here and elsewhere is, none the less, more easily related to comparable ultrastructure in other groups of Carboniferous lycopsid megaspores and could suggest a link with such genera as Zonalesporites and early Lagenicula. This would be in keeping with current concepts regarding the most primitive ultrastructural type within lycopsid megaspore walls.     

A comparison of Asturian lepidodendroid lycophytes from the USA and the Euramerican Variscan Front

Species belonging to the Carboniferous genera Lepidodendron and Lepidophloios are well known from the coalfields of Pennsylvania (Lower Asturian (Westphalian D) substage of the Pennsylvanian) through the publications of Lesquereux and White. They believed that the lycophyte flora was rather distinct from other contemporaneous coal floras elsewhere due to its isolation. A full revision of the lepidodendroid lycophyte species is given here and this reassessment permitted comparisons with those floras known from the European and Canadian Maritimes coalfields. Differences in species distribution suggest there was a barrier (Arcadian Highlands) to species distribution to and from the coalfields of Pennsylvania. Several species are recognized only from the coalfields of Pennsylvania, although the number has been significantly reduced from the original publications.     

Ammonite taphonomy and stratigraphy of the Bajocian at Maizet,south of Caen (Calvados,NW France)

A study of the ammonite assemblages from the “Oolithe ferrugineuse de Bayeux” Formation of Bajocian age is presented herein. The section at the locality of Maizet shows a high level of stratigraphic condensation, and taphonomic reworking is common within the sequence. All the ammonites being studied are classified herein as having been reworked, transported or displaced on the sea-floor prior to burial, and as such, are determined taphonomically as being resedimented or reelaborated fossil elements. Seven evidences of reelaboration within the sequence under investigation are detailed here. The palaeontological units, so-called taphorecords, characterized by distinctive taphonomic features, are used to directly or indirectly assign beds to biochronostratigraphic units. In addition, identification of taphorecord relationships regarding successive or contemporaneous deposition allows their registratic succession and order of depositional events to be inferred. The latter may be deduced on the basis of bed succession or by reference to stratigraphical intervals that now are only represented in the stratigraphic column by fossils. Deposition by tractional currents and winnowing is indicated by sharp bed-base and by reworked fossil elements. Biochronostratigraphic correlation with other sections of the inland Bajocian successions in the Calvados area (Bretteville, Feuguerolles) highlights a common depositional evolution that may be related to an eastward-deepening carbonate ramp.     

A redescription of the trigonotarbid arachnidPocononia whitei (Ewing 1930)

The trigonotarbid arachnid,Pocononia whitei (Ewing 1930), is redescribed and referred to the family Eophrynidae as the oldest known eophrynid. It suggests that trigonotarbids had diversified into the recognised Upper Carboniferous families by the Lower Carboniferous.     

Spores and Pollens from Crude Oil of Turpan Basin,Xinjiang

Sixty-eight species of fossil spores and pollens referred to 39 genera extracted from the crude oil samples collected from the Turpan Basin of Xinjiang are recorded in this paper. Based on the investigations of fossil spores and pollens in petroleum, the questions on petroleum migration and source rocks are discussed. It is expounded and proved theoretically and practically that the phenomenon that the crude oil samples usually contain the fossil spores and pollen grains with different geological ages from reservoir rocks should result from petroleum migration, but not from resedimentation. The fossil spores and pollens in crude oil of the Middle Jurassic reservoir of the Qiktim Oil-Field of the Turpan Basin comprise mainly Leiotriletes pflugi, Deltoidospora gradata, D. magna, Cyathidites australir, C. minor, Biretisporites cf. potoniaei, Dictyophyllidites harrisii. Cibotiumspora paradoxa, C. jurienensis, Gleicheniidites rousei, G. conflexus, Undulatisporites concavus, U. pflugii, Granulatisporites arenaster, G. minor, Todisporites minor, Osmundacidites wellmanii, dpiculatisporis variabilis, Leptolepidites major, Aratrisporites scabratus Cycadopites nitidus, C. typicus, C. subgranulosus, Chasmatosporites elegans, Classopollis classoides, C. itunen- sis, C. annulatus, C. qiyangensis, Callialarporites dampieri, C. radius, lnaperturopollenites det- tmannii, Protoconiferus funarius, Paleoconiferus asaccatus, CaytonipoUenites pallidus, Vitreis- porites jurassicus, V. jansonii, Pseudowalchia ovalis, P. landesii, P. biangulina, Podocarpidites unicus, P. major, P. multicinus, P. multesimus, P. rousei, P. wapellaensis, Platysaccus lopsinensis, Ovalipollis enigmatica, O. minor, O. canadensis, Pteruchipollenites thomasii, Alisporites grandis, A. bilateralis, Pityosporites similis, P. divulgatus, Piceites expos us, P. podocarpoides, P. latens, Protopicea exilioides, Pseudopicea variabitifornus, Piceaepollenites complanatiformus, Abietineaepollenites dunrobinensis, A. microalatus, A. minimus, Cedripites minor, Eucommiidites troedssonii, etc. Some of the species are also found from the crude oil sampls taken from the Middle Jurassic reservoir of the Shengjinkou Oil-Field of the Turpan Basin. The above mentioned species of spores and pollens are widely distributed in the Lower to Middle Jurassic sediments of North America, Europe, Australia and China. They have also been found from the Lower to Middle Jurassic sediments of the Turpan Basin. Judging from the spores and pollen in petroleum, it may be concluded that the Lower Jurassic Badaowan-Sangonhe Formation and the Middle Jurassic Xishanyao-Toudenhe Formation should contain the favorable petroleum source rocks in the basin. As to petroleum migration mechanism, it is considered that petroleum must have migrated for comparatively short distances to accumulate into petroleum pools in this region.     

The Crassispora kosankei–Cystoptychus azcuyi palynozone of the Upper Carboniferous Tupambi Formation,Tarija Basin,northern Argentina

Well-preserved and diverse palynomorph assemblages were recovered from surface and core samples from the middle to upper section of the Tupambi Formation. The latter is the basal unit of the Macharetı́ Group (Upper Carboniferous) of the Tarija Basin, northern Argentina. Assemblages are composed of trilete miospores, one hilate species, monosaccate pollen grains (one species striated), one praecolpate species and green algae (Botryococcus). Two key species are Cystoptychus azcuyi sp. nov. and Crassispora kosankei (Potonié and Kremp) Bharadwaj emend. Smith and Butterworth enable definition of the first palynozone for this basin. The age, as well as the biostratigraphic and paleogeographic significance of the palynoflora is discussed.     

Some notes on Marattia anglica from the Jurassic of Yorkshire

In this paper the spores of the Jurassic fern Marattia anglica are redescribed. It appeared that at least 30% of the spores have a more or less trilete, instead of the usual monolete, laesura. In Marattia muensteri, M. hoerensis and M. crenulata (three species from the Jurassic), trilete spores also appeared to occur, although in much lower percentages than in M. anglica. The spores of M. anglica are compared with recent Marattia spores and with Jurassic dispersed spores.Furthermore, the systematic position of M. anglica and other Jurassic Marattia species is discussed.     

藏北申扎地区下石炭统永珠组下部孢子组合的特征及意义

报道藏北申扎永珠区德日昂玛—下拉剖面的永珠组孢子组合,发现孢子43属,70余种(包括未定种)。组合特征如下:1)缺乏欧美植物地理区早石炭世典型的石松类植物的小孢子Lycospora属及早石炭世晚期(维宪期)重要孢子属;2)出现较多早石炭世早期(杜内期),甚至泥盆纪晚期分子。呈现出新老化石的混合现象;3)北半球和南半球孢子的混合组合,同时也是冷、暖微古植物群混合,既有相当于中国早石炭世晚期大塘期以及西欧维宪期典型属种,又有南半球澳大利亚(包括巴西和非洲大陆)的维宪期的典型种。从孢子化石混合现象看,永珠组应为近岸浅水或滨海条件下的沉积,下伏地层的孢子化石再沉积现象说明当时有一次很大的海平面下降,在邻近地区出现了大面积的剥蚀区。说明杜内期末期—维宪期初期,申扎地区出现一次由冈瓦纳大陆冰川发育造成海平面相对下降。形成区域上不整合界面———洛工组或“巴日阿朗寨段”底部的不整合界面。混合孢子组合中的寒冷气候条件下的孢子化石的发现,印证了杨式溥、范影年和林宝玉推断的冈瓦纳冰川自早石炭世维宪期(大塘期)开始就影响到西藏申扎的推论。     

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.     

Albian Palynostratigraphy of ODP Leg 207 (Holes 1257A, 1258C and 1260B), Demerara Rise,Equatorial Atlantic

Palynological analyses were carried out in 96 core samples with the objective of determining the relative age of calcareous clays, in holes 1257A, 1258C and 1260B of ODP Leg 207, drilled on the Demerara Rise, northern coast of Suriname, Equatorial Atlantic. The palynological assemblages recovered consisted of spores, pollen grains, dinoflagellate cysts, palynoforaminifers and prasinophytes and appeared reasonably well preserved. The miospores showed little diversification, where the most significant genera were Crybelosporites and Elaterosporites. The dinocysts showed greater diversity and abundance, predominating over the miospores in the three holes. In the three holes analyzed, eight genera and three species of spores, eight genera and eleven species of pollen grains, and 24 genera and 44 species of dinoflagellates were identified. The middle to late Albian age was determined on the basis of bioevents of recognized species with chronostratigraphic value. The species diagnosed mostly included the miospores Elaterosporites protensus, Elaterosporites verrucatus, Inaperturopollenites simplex and the dinocysts Cribroperidinium muderongense, Dinopterygium cladoides, Litosphaeridium arundum, Litosphaeridium conispinum, Oligosphaeridium complex and Stiphrosphaeridium anthophorum.     

鄂东南早白垩世灵乡群孢粉组合

本文根据从大冶灵乡-陈重山剖面的中部、灵乡狮子山东侧采坑和鄂城太和1孔的相当层位中所获得的孢粉组合(共67属120余种,其中新种9个,新联合2个),认为灵乡群孢粉组合属于 Classopollis、Psophosphaera-Cicatricosisporites、Schizaeoisporites-没有或极个别的出现被子植物花粉的组合类型,其地质时代应为早白垩世早期-中期(凡兰吟期-巴列姆期)。并推测鄂东南地区当时的气候属于偏干旱的热带-亚热带型。     

柴达木盆地侏罗系油源的孢粉学证据

记述了青海柴达木盆地侏罗系油储原油中萃取出的孢子花粉化石27属45种。基于原油中孢粉化石的研究及其与潜在油源岩中孢粉化石的对比,确定了含油区的油源岩。并根据孢子花粉母体植物所反映的古生态特征探讨了油源岩形成的环境。研究结果表明,下侏罗统小煤沟组和中侏罗统大煤沟组应为该含油区的油源岩系。研究区油源岩形成于温暖湿润气候下的湖沼环境。     

Linking taphonomy to community-level abundance: Insights into compositional fidelity of the Upper Triassic shell concentrations (Eastern Alps)

Although actualistic live/dead comparisons lead to robust estimates of fidelity of modern death assemblages, quantitative evaluation of fidelity of fossil assemblage remains uncertain. In this paper, effects of storm reworking on compositional fidelity of the Upper Triassic shell concentrations (Eastern Alps, Austria) are evaluated. An exploratory approach is based on comparison of reworked and non-reworked assemblages in ordination analyses. Non-reworked assemblages of one or more communities provide a baseline for evaluation of fidelity of reworked assemblages. In siliciclastic-rich intervals of the Kössen Formation, shell concentrations are represented by (1) packstones with small, shallow infaunal bivalves, (2) floatstones and pavements with large semi-infaunal bivalves, and (3) bioclastic marlstones. In carbonate-rich intervals, bioclastic floatstones with bivalves and brachiopods occur. Analyzing all shell concentrations, eight sample groups sharing similar species composition are discriminated. Limited effect of storm reworking on composition of shell concentrations is indicated by (1) a general persistence of six sample groups when only non-reworked assemblages are analyzed, (2) similarity in composition between reworked and non-reworked assemblages within sample groups, and (3) compositional segregation between non-reworked assemblages of distinctive sample groups, mostly without any reworked assemblages of intermediate composition.Depth-related variations in dead-shell production, shell destruction and body size governed preservation and distribution of the shell concentrations along onshore-offshore gradient in the Kössen Basin. First, at times when environmental conditions were unfavorable for shell producers, coupled with high background shell destruction rates, limestone beds formed during storm events were shell-poor. Second, less common shell concentrations in upper than in lower parts of siliciclastic intervals can be related to higher environmental stress in shallower habitats. Third, the difference between shell concentrations dominated by small and large bivalves is driven by between-habitat differences in body size and is not due to a differential sorting of small and large shells. Combining community analysis based on species abundances with taphonomic analysis can thus be helpful in tracking fidelity of fossil assemblages.     

Acritarchs,miospores and correlation of the Ludlovian-Downtonian and Silurian-Devonian boundaries

An attempt is made to use palynomorphs to correlate the Ludlovian-Downtonian and the Silurian-Devonian boudaries in successions from the British Isles, Estonia, Podolia and north Africa. Miospores are found to be of most use for this purpose: (a) the micronatus-newportensis zone can be recognised in the Anglo-Welsh area, in Podolia and in north Africa, and the base of this zone indicates a level above, but close to, the Silurian-Devonian boundary; (b) the Ludlovian-Downtonian boundary is well-defined in the Anglo-Welsh area on the basis of miospores and can be determined approximately in north Africa and Estonia since several miospore species appear at or close to this boundary. The lack of stratigraphically important acritarch and miospore species in the Silurian-Devonian stratotype at Klonk (Czechoslovakia) underlines the importance of the Podolian sequence for the recognition of the Silurian-Devonian boundary in continental sequences. Recognition of the Ludlovian-Downtonian boundary in Podolia is difficult since the miospores below the Borschov Horizon have not been systematically described and are probably rare. Further, there are difficulties in using acritarchs for interregional correlation since they appear to be considerably influenced by provinciality and local environmental factors. From the palynological point of view therefore the Ludlovian-Downtonian boundary should be chosen from a sequence in which miospores are common, since one based on acritarchs would involve two stratotypes, one from the Deunffia-Domasia, and one from the carminae, realms. Finally, some features of current palinspastic continental plate reconstructions are discussed in the light of acritarch provinciality.