Ostracod and conodont faunal changes across the Frasnian-Famennian (Devonian) boundary at Els Castells,Spanish central Pyrenees

Diverse conodont and silicified ostracod assemblages were found in the Spanish Pyrenees (Els Castells section), in the Frasnian/Famennian boundary beds (late rhenana and/or linguiformis to late triangularis zones), in strata below and above the well-known Kellwasser Extinction Event. Many of the ostracods studied here are conspicuous elements of the “Thuringian Mega-Assemblage”, and show maximum affinities with faunas from the southeastern Cantabrian Mountains (Spain), eastern Thuringia and the Harz (Germany). The composition of the faunas, however, is not uniform through the Els Castells section. A rather sharp break exists, roughly coinciding with the Frasnian/Famennian boundary. The break is characterized by the disappearance of many ostracods typical of the “Thuringian Mega-Assemblage”. This correlates with an important change in the conodont faunas related to the Kellwasser Event. The Frasnian (late rhenana and/or linguiformis zones) palmatolepid-polygnathid biofacies is followed in Famennian strata (middle and late triangularis zones) by a palmatolepid-icriodid biofacies. The icriodid maximum in the earliest Famennian rocks of the Pyrenees correlates with the “Icriodid Peak” described elsewhere. These changes depend on the age and palaeoenvironmental conditions.     

The palaeopsychrosphere in the Devonian

The interpretation of Palaeozoic marine benthonic ostracods of the Thuringian ‘Ecotype’ or ‘Mega‐assemblage’ as indicative of a palaeopsychrosphere has been controversial. We review the evidence and conclude that the characteristics and distribution of these ostracods are consistent with the existence of deep, cold, well‐oxygenated water masses, formed by high‐latitude sinking of surface waters, in the Devonian oceans, comparable with those of the modern ocean that constitute the psychrosphere (waters below the thermocline with temperature <10°C). We present a new palaeoceanographic model for the Frasnian–Famennian (Late Devonian) Kellwasser events that resulted in the extinction of 75% of marine ostracod taxa, mostly neritic or pelagic forms, while the deep water Thuringian Mega‐assemblage was relatively unaffected. We offer an explanation for the unlikely preservation of examples of such a deep water (bathyal to abyssal) ostracod fauna that involves upwelling of deep cold waters on continental margins.     

Late Devonian global ostracod palaeobiogeography

A global Late Devonian ostracod database is constructed, incorporating new materials from South China and Northwest China. Four palaeobiogeographical units (Cathaysia, North America, Europe and peri‐Gondwana) are recognized during the Frasnian and five palaeobiogeographical units (Cathaysia, North America, Europe, Siberia and Australia) in the Famennian. Three controlling factors (climatic zonation, geographical isolation and global sea‐level changes) are identified to have played roles in shaping the palaeogeographical regionalization of ostracod faunas in the Late Devonian. The ostracod palaeobiogeography in the Frasnian was mainly influenced by climatic zonation, while rapid changes in tectonic configuration in the Famennian drastically altered the global palaeobiogeography of ostracods. The palaeobiogeographical regionalization of ostracod faunas suggests that Laurussia and Gondwana continued to draw near during the Late Devonian, with the first collision occurring in Southern Central Europe in the Famennian. The South China plate drifted northward to the Kazakhstan plate away from the Australian plate, which gradually became isolated during the Famennian Stage.     

Les Ostracodes de la partie supérieure de la Formation deTeferguenite (Givétien) et de la Formation de Marhouma (Givétien-Famennien) de la coupe du km 30 (Saoura,Sahara algérien)

More than fifty ostracod species, twenty-two of which are Entomozoacea, have been identified in the upper part of the Teferguenite Formation and in the Marhouma Formation. The zonal sequence established on the Entomozoacea is applicable to the Frasnian and the Famennian of the Algerian Sahara; seven zones are recognized. One new species, Tubulibairdia marhoumaensis nov. sp., is described.     

西藏南部聂拉木地区晚泥盆世—早石炭世的介形类

本文系统描述西藏南部聂拉木地区晚泥盆世–早石炭世介形类共计15属24种。根据介形类的组合面貌及孢子、牙形刺的研究结果推断,亚里剖面上的亚里组时代为晚泥盆世–早石炭世,泥盆系-石炭系界线(D-CB)大致位于亚里东沟段顶部至沟陇日段。亚里组产出的介形类生态组合属于光滑速足目集群或艾菲尔生态型,指示亚里组在沉积时为远岸浅水沉积环境,且在上部腊扎蒲段水深变浅。亚里组介形类面貌与华南泥盆纪介形类相似程度高,与俄罗斯和欧美地区也有相似的属种,说明泥盆纪-石炭纪之交介形类的地理隔离并不显著,在各个板块之间有属种交流的可能。     

Middle Permian Ostracods from Tak Fa Limestone, Phetchabun Province, Central Thailand

This paper presents the first Permian ostracod fauna discovered in Thailand. The ostracods are recovered from the Tak Fa Limestone (Middle Permian) in Phetchabun province, central Thailand. The ostracods belong to eight genera and 15 species. Four species are newly described: Sargentina phetchabunensis nov. sp., Geffenina bungsamphanensis nov. sp., Reviya subsompongensis nov. sp. and Bairdia takfaensis nov. sp. The ostracod assemblages characterize a shallow marine, near shore environment at the time of deposition. Except for one species, which shows palaeobiogeographical links between Central Thailand and South China, all the other species are endemic.     

Les ammonites du Pliensbachien du jebel Bou Rharraf (Haut Atlas oriental, Maroc)

The originality of the sedimentary deposits and ammonite faunas in the jebel Bou Rharraf concerns “Ammonitico Rosso” facies, the westernmost known for the Pliensbachian, and a strong diversity of the Phylloceratida (Phylloceras, Calaiceras, Zetoceras, Partschiceras and Juraphyllites). The morphological disparity is also important in Galaticeras, Miltoceras and Tauromeniceras. If some taxa like Miltoceras taguendoufi and Mauretaniaceras elmii nov. gen., nov. sp. seem endemic to the High Atlas, most part of the Pliensbachien ammonites of the eastern High Atlas are classic for the southern margin of the western Tethys. Three genera (Callomoniceras, Appenninoceras, Mauretaniaceras) and three new species (Miltoceras involutum, Tropidoceras heterogeneum, Mauretaniaceras elmii) are described. An analysis using the “Discrete Cosine Transform” (DCT) method allows the better understanding of the morphospace of the rib patterns for the Fuciniceras from jebel Bou Rharraf. The biostratigraphy of the High Atlas is also improved with a set of 19 biohorizons for the Pliensbachian and the base of the Toarcian that are correlable with the Tethyan areas.     

Gastropodes sinémuriens du Monte Cucco (Apennins d’Ombrie-Marche, Italie centrale)

Recent researches carried out in the uppert part of the “Calcare Massiccio” formation of Monte Cucco allowed to recover a rich Sinemurian fauna of gastropods, bivalves, brachiopods, ammonoids and some solitary corals. The gastropod fauna is greatly dominant and includes 18 species which belong to the superfamilies Pleurotomarioidea, Fissurelloidea, Amberleyoidea, Neritoidea, Loxonematoidea, Cerithioidea, Nerineoidea, Littorinoidea and Acteonoidea. Ten species of gastropods are here described for the first time. This fauna shows a marked affinity with that of the Sinemurian of Sicily. Under a paleoecological point of view, it is indicative of free marine conditions, in photic zone but under a weak hydrodynamism, and therefore may suggests the reference to a deep infralittoral or upper circalittoral environment.     

Évolution du trait de côte à l’Holocène supérieur dans la Sebkha El-Guettiate de Skhira (Golfe de Gabès, Tunisie) à travers sa faune d’ostracodes et de foraminifères

A 122 cm-long core was taken in the El-Guettiate Sebkha of Skhira (southeastern part of Tunisia) in order to investigate the recent palaeoenvironmental evolution of this region. The quantitative and qualitative analysis of ostracod and benthic foraminifera assemblages coupled with a correspondence analysis allows the reconstruction of palaeoenvironmental changes during the Holocene in this area. Four typical associations of ostracods (open marine, coastal marine, lagoonal and estuarine brackish) and two associations of benthic foraminifera (coastal and lagoonal) were distinguished. The onset of restricted lagoonal environments linked to the building-up of sand spit led to the onset of restricted lagoon and brackish environment at cal. 5408 years BP. The Shannon and equitability index of diversity were used to decipher the structural variations of the populations of ostracods and benthic foraminifera along the sampled core. We note a reduction in the Shannon index from the bottom to the top, which indicates a progressive isolation of the biotope. The open lagoonal episode is characterized by high values of diversity. During restricted lagoonal episodes the Shannon and equitability index are reduced. The correspondence analysis reveals an environmental gradient related to the marine influence. It shows an antagonism between the widely opened estuarian lagoonal species and those of restricted lagoon. The less opened estuarian lagoonal taxa occupy an intermediate position. Based on these evidences, microfauna carried out in the El-Guettiate Sebkha allows us to recognize four phases beginning with a widely opened estuarian lagoon (ca. cal. 7460 years PB), followed by a restricted lagoon (ca. cal. 5408 years BP) and finally a brackish lagoon evolving towards the present-day sebkha environment. The opened estuarine lagoon is characterized by high values of species richness and diversity indices.     

西藏聂拉木晚奥陶世的介形类

文中首次报道西藏聂拉木地区亚来水厂剖面上奥陶统甲曲组介形类16属30种,介形类以古足介目类和圆足介目类为主,少量速足介目类。根据该剖面介形类时代特征,可以推断甲曲组应属于晚奥陶世早期,大致为Sandbian期—Katian期。该介形类生态组合为艾菲尔生态型,指示甲曲组在沉积时为近岸浅水环境。晚奥陶世喜马拉雅地层区与华南扬子区及塔里木介形类面貌相似,应属于相同的生物地理分区。     

Ostracodes et incursions marines dans l’Holocène terminal du lac Retba (Cap Vert, Sénégal)

The study of marine incursions based on ostracods is carried out for the first time in the late Holocene, with core sediments of the Lac Retba edge. Twenty-four species are identified along the core; most of them are encountered in the Gulf of Guinea shelf and its adjacent lagoons. For the first time Buntonia olokundudui Reyment and Van Valen, Hermanites foveolata Omatsola and Soudanella africana Omatsola are recorded in Senegal. Four ostracods assemblages are evidenced along the core, corresponding to different stages of the lake evolution. Cyprideis nigeriensis Omatsola, Neomonoceratina iddoensis Omatsola and Aglaiocypris gambiensis Witte dominate the first assemblage; they indicate a lagoon slightly open to the sea and bordered with mangrove swamps under relatively humid climate conditions. The second association yields the most diversified ostracod fauna with C. nigeriensis, N. iddoensis and high proportion of reworked “marine species” which evidence a marine little gulf bordered by mangrove under a humid climate. The third, monospecific association (C. nigeriensis) is typical of a closed and hypersaline lagoon under dry climate conditions. An oligospecific association with C. nigeriensis, Pseudoconcha omatsolai Witte and very scarce reworked “marine species” occurs at the top of the core and characterises an open and hypersaline lagoon under arid climate conditions. Ostracods evidence two marine incursions. The first and the stronger one is dated here for the first time between 1420 and 1250 years B.P. The more recent is the weaker and is not yet dated. Evidence of the beginning of the Retba Lake closure towards 680 years B.P. appears at the top of the core, as indicated by high reduction of ostracods abundance, predominance of reticulate Cyprideis and disappearance of the “marine species”, while salts precipitated at the bottom of the lake.     

Zooplankton (Cladocera, Ostracoda), Chironomidae and other benthic faunal remains in sediment cores from nine North African wetland lakes: the CASSARINA Project

Palaeolimnological studies were carried out on sediment cores from nine North African wetland lakes. The lakes represented a variety of habitats ranging from freshwater to mixohaline conditions and with and without direct connections to the sea. Sediment cores were examined for records of recent environmental change during the 20th century period. Faunal remains analysed in the sediments included those of Cladocera, Ostracoda, Chironomidae, Mollusca and, at the sites with marine connections, Foraminifera. Cyprideis torosa littoralis was the most common ostracod, occurring in sediments from the seven sites linked with the sea and also in brackish water Sidi Bou Rhaba. In acid Megene Chitane ostracods were scarce, being represented by a single species (Cypria ophtalmica). Candona neglecta completely disappeared at two sites (Sidi Bou Rhaba and Bokka) during the 20th century. Of the Cladocera, Chydorus sphaericus was common in the moderately mixohaline sites and but Heterocypris salina occurred only where marine salinities were occasionally achieved (in Zerga, Ichkeul and Korba). Microinvertebrate assemblages in the Nile Delta lake cores and to a less extent in Zerga showed a clear response indicative of more fresher conditions occurring during the latter part of the 20th century. However the freshening trend began prior to construction of the Aswan High Dam (mid 1960s).With the exception of the most saline site (Korba), microinvertebrate communiuties at all the CASSARINA sites have experienced major disturbances during the 20th century. Changes in freshwater availability associated with increased human usage of water resources is perceived as a major factor regulating the abundance and occurrence of aquatic microinvertebrate species at these sites     

Pliocene coastal palaeomorphology and ostracod faunas of the Bass Strait hinterland,southeast Australia

Early to late Pliocene sedimentary strata present across the northern Bass Strait hinterland, southeastern Australia yield extensive fossil proxy data relevant to the interpretation of high sea level coastal palaeomorphology. Within the Pliocene Whalers Bluff Formation exposed in coastal cliffs near the township of Portland, Victoria, marine microfossil faunas delineate two broad cycles of deposition. Both these sedimentary cycles are bound below by unconformity surfaces. Within the lower sedimentary cycle, a basal stress-tolerant (low diversity) marginal marine microfossil fauna devoid of ostracods and suggestive of bottom-water hypoxia, is succeeded by a diverse shallow marine ostracod fauna dominated by stenohaline species indicative of a sheltered (but open) oceanic embayment. This lower sedimentary cycle has an early Pliocene (Zanclean) age. Equivalent shallow marine (e.g. coastal embayment) deposits occur broadly across the coastal hinterland of southeastern Australia—reflecting the generally higher global sea levels of this time. The upper cycle in the cliff exposures at Portland is late Pliocene (Piacenzian) in age. Equivalent deposits across the Bass Strait hinterland are restricted to former incised river valley settings. Euryhaline estuarine/coastal lagoon Ostracoda are present throughout the upper cycle in the Portland cliffs. These are associated with a low diversity microfauna at the base of the upper cycle and a high diversity microfauna towards the top of the cycle. Early Pliocene coastal marine deposits can be distinguished from late Pliocene coastal marine deposits across the northern Bass Strait hinterland on the basis of the presence or absence of certain open marine (‘stenohaline’) ostracod species.     

粤西怀集盆地白垩系马屋组的介形类化石

依据闸岗剖面地表及钻井样品的分析鉴定,粤西怀集盆地白垩纪闸岗群马屋组产介形类化石10属17种,本文描述其中9属14种,包括1新种。介形类组合以Eucypris最繁盛,次为Ziziphocypris和Darwinula,称Eucypris hubeiensis-Ziziphocypris simakovi-Darwinula leguminella组合。马屋组与湖北贾店组的介形类组合面貌非常相似,可以进行对比,层位大体相当,其时代应属早白垩世最晚期(Albian)-晚白垩世早期(Cenomanian)。     

Late Eifelian and Early Givetian ostracod assemblages from Wellin,Hotton and On-Jemelle (Ardenne,Dinant Synclinorium,Belgium). Paleoenvironmental implications

The study of 3430 ostracods collected in the Lomme, Hanonet and Trois-Fontaines formations (Late Eifelian/Early Givetian) in four sections of the Dinant Synclinorium (Ardenne) allowed the recognition of more than 75 taxa. Their study displays the progressive evolution from an external mixed siliciclastic-carbonate ramp to a carbonate platform around the Eifelian/Givetian boundary. Ostracods from the Lomme Fm are published here for the first time. The leperditicopid ostracods are probably indicative of brackish water environments during the deposition of the Trois-Fontaines Fm, and consequently point to wet and warm climatic conditions during Early Givetian times in the Dinant Synclinorium. Their absence in widespread lagoonal environments in the upper part of the Givetian may be on the contrary related to very arid climate conditions. That important climatic change is probably in relation with the Taghanic Biocrisis.     

Evolution of Devonian biodiversity of radiolarians with two porous spheres and one main spine

Features and major distinctions in the appearance and distribution of radiolarians with two porous spheres and one main spine in the Devonian basins are considered. Four solitary population waves and expansion scenario of radiolarians of this morphotype have been recognized in the Devonian. A new species, Radiobisphaera rozanovi sp. nov., from the Upper Emsian, Upper Eifelian, and Middle Frasnian of the southern Ural Mountains, from the Upper Eifelian of the Prague Basin (Barrandian), from the Middle-Upper Frasnian of the Rudnyi Altai, and from the Lower Famennian of the Timan-Pechora Basin and the Polar Ural Mountains is described.     

山东蒙阴盆地常路组二段(古新世——早始新世)介形类化石

本文记述了2011年采自山东蒙阴盆地常路组二段的介形类化石共计6属10种4未定种,可建立一个Metacypris-Paracandona-Cyclocypris-Candona-Candoniella组合。根据介形类化石与国内已知化石组合对比研究,常路组二段的时代大致为古新世——早始新世。     

甘肃玉门下沟地区早白垩世下沟组介形类

甘肃玉门下沟地区下沟组介形类化石十分丰富,该地区下沟组介形类化石共计9属4亚属,21种,本文描述了其中4新种,即Cypridea(Cyamocypris)xiagouensissp.nov.,Cypridea(Cypridea)subunicostatasp.nov.,Stenestroemiasubpeculiarissp.nov.和Stenestroemiaxiagouensissp.nov.。该介形类化石组合尤以Cypridea最为繁盛,通过分析介形类属种的形态特征和化石组合特征并结合岩性特征,推断下沟组的地质时代为早白垩世巴列姆期;并认为下沟组为水动力较弱的淡水-微咸水河湖相沉积。     

Biostratigraphy and Paleobiogeographic implications of the Cenomanian–Early Turonian Ostracods of Egypt

The present study deals with the Cenomanian–early Turonian ostracods in the southern Sinai, Egypt. The investigated sequence includes the Raha and Abu Qada formations. The Raha Formation consists of distinctive Cenomanian taxa such as Cytherella aegyptiensis, Veeniacythereis maghrebensis, V. jezzineensis, V. streblolophata streblolophata, Monoceratina trituberculata, and Glenocythere reticulata. Based on the ostracod species, four local biozones are recognized, including Veeniacythereis jezzineensis – Metacythereopteron berbericum, Cytherella eosulcata – Xestoleberis derorimensis, Amphicytherura ziregensis and Perissocytheridea istriana – Cythereis fahrioni. The paleobiogeography of the considered ostracods suggests that there are two bioprovinces, the first of which is the North African province and includes Egypt, Tunisia and Algeria. The second bioprovince represents the Middle East province and includes Lebanon, Oman and Iran. The strong resemblance between the two bioprovince indicates a relatively good communication along the margin of Southern Tethys during the Cenomanian and improved marine ostracod exchange.     

Galets aménagés en provenance des terrasses supérieures du Rhône au sud de Lyon (Sud-Est de la France)

Between 1990 and 1993, we found 175 pebble-tools and two flake-tools on the western high-terrace south of Lyon (Southeast, France) at two different levels (290 m and 235 m NN). Most of them show the classical spectrum of choppers and chopping-tools, joined by six protobifaces. They all belong to the developed Olduvan (Olduvan II). On the lower terrace, corresponding with its younger age, we met a more progressive pebble-tool culture. Both stocks are secondary sites, brought from the East by the most extreme tongue of the Rhône glacier and, therefore, cannot be dated exactly.