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Katy, TX, United States

Maranhites isaacsonii sp. nov. was recovered from an outcrop sample of the Upper Devonian Cabanillas Group, Oxapampa Province, Peru. This acritarch displays the discrete equatorial thickenings that characterize the genus, but differs from all described species by having a lobate vesicle margin with processes or process groups. The processes taper distally and terminate in capitate, rounded, or clavate tips. The palynomorph assemblage is dominated by marine elements, including acritarchs, prasinophytes, scolecodonts, and chitinozoans. The occurrence of Retispora lepidophyta indicates a Late FamennianEarly Tournaisian (Fa2c-Tn1a) age for the sample yielding Maranhites isaacsonii sp. nov. Palynomorphs exhibit a thermal alteration index equivalent to gas-window maturation. © 2010 AASP-The Palynological Society. Source


Paris F.,Rue des Jonquilles | Paris F.,CNRS Geosciences Laboratory of Rennes | Miller M.A.,Irf Group Inc. | Al-Hajri S.,Aramco Services Company | Zalasiewicz J.,University of Leicester
Review of Palaeobotany and Palynology | Year: 2015

Sixty one core samples from three shallow core holes (Qusaiba-1, Baq'a-3 and Baq'a-4) penetrating the Qalibah Formation (Qusaiba Member) in the North Central Saudi Arabia were investigated. These core slabs corresponding to grey-greenish hemipelagic shale or silty-shale yield well-preserved and very abundant early Silurian chitinozoans. Most of the recorded chitinozoan assemblages are diverse and include several new species occurring with well-known species. An informal early Rhuddanian chitinozoan assemblage dominated by Cyathochitina caputoi is documented in the lowermost part of the Qusaiba Member. The six chitinozoan biozones defined above this basal assemblage range from Aeronian to Telychian. They are considered of regional value for northern Gondwana. From the lowest to the highest they are the Angochitina qusaibaensis (pro parte), Conochitina alargada, Angochitina hemeri, Angochitina macclurei, Tanuchitina obtusa and Euconochitina silurica biozones. The older regional biozones have been previously documented in Saudi Arabia whereas the two youngest ones, the eponymous index species of which were described from the subsurface of the Algerian Sahara, are documented for the first time in the Arabian Peninsula. Four subbiozones, of at least of regional application, are also defined in order to improve the precision of biostratigraphic correlation between Silurian lithostratigraphic units cropping out along the Arabian Shield and their counterparts in the subsurface of Central Saudi Arabia. Thanks to the closely spaced and to the regular sampling, the total range of several highly diagnostic forms as well as the interval of uncertainty between the successive chitinozoan biozones are better constrained. A hiatus with a duration of late Rhuddanian to early Aeronian separates the lowest informal chitinozoan assemblage from the qusaibaensis Biozone. A recent detailed study of the graptolites in the three cored holes provides independent chronostratigraphical control calibrating the previous chitinozoan-based age assignments. The qusaibaensis (pro parte), the alargada, and the hemeri chitinozoan biozones occur with the mid-Aeronian convolutus graptolite Biozone whereas the macclurei chitinozoan Biozone extends through the early Telychian guerichi and turriculatus graptolite biozones. The obtusa and the silurica chitinozoan biozones occur in an interval devoid of usable graptolites. They are referred to the mid-late Telychian as they do not contain typical Sheinwoodian species.Besides the abundant chitinozoans and acritarchs, sporadic occurrences of scolecodonts and of eurypterid cuticle fragments are also noted in the organic residues. The presence of eurypterids reflects a shallowing trend in the sedimentary record, which is consistent with the distribution of the graptolite remains (siculae and/or rhabdosomes). Indeed, graptolites are common throughout the Qusaiba Member, except in the youngest processed samples presaging the shallower environments prevalent in the Sharawra Member. The taphonomy of the chitinozoans (isolated vesicles, chain-like structures, clusters, coprolites) and their environmental context is briefly discussed.Fifteen new species are described and illustrated: Ancyrochitina alhajrii sp. nov., Ancyrochitina camilleae sp. nov., Armoricochitina crassicarinata sp. nov., Armoricochitina gengi sp. nov., Bursachitina baqaensis sp. nov., Conochitina viiuae sp. nov., Cutichitina minivelata sp. nov., Cyathochitina neolatipatagium sp. nov., Fungochitina merrelli sp. nov., Muscochitina olivieri sp. nov., Plectochitina alisawyiahensis sp. nov., Plectochitina alnaimi sp. nov., Plectochitina jaquelineae sp. nov., Plectochitina lucasi sp. nov., and Spinachitina geerti sp. nov. © 2014 Elsevier B.V. Source


Paris F.,Rue des Jonquilles | Paris F.,CNRS Geosciences Laboratory of Rennes | Verniers J.,Ghent University | Miller M.A.,Irf Group Inc. | And 3 more authors.
Review of Palaeobotany and Palynology | Year: 2015

The continuously cored Qusaiba-1 drilled in North Central Saudi Arabia penetrated successively the Qalibah, Sarah and Qasim formations. Silurian graptolites and chitinozoans from the Qusaiba Member of the Qalibah Formation were previously investigated. The present study focuses on the Upper Ordovician and lowermost Silurian parts of the core hole. Part of the sample set yielded abundant and well-preserved specimens associated with eurypterid remains, scolecodonts, acritarchs and cryptospores. Other samples from glacially derived shaly sediments contain only a few fragmented chitinozoan vesicles of Middle and Late Ordovician species indicating reworking through glacial processes. Four different chitinozoan assemblages are identified. The first recorded chitinozoan assemblage is restricted to the deepest processed sample (core 56). It contains Belonechitina cf. robusta, Hercochitina sp. A, and Spinachitina cf. kourneidaensis, and taxa also represented in the second assemblage, e.g., Fungochitina spinifera and Euconochitina species. This first assemblage, however, lacks some of the diagnostic species of the second one (e.g., Acanthochitina barbata, Tanuchitina cf. elongata) and suggests a slightly older late Katian age. The second recovered chitinozoan assemblage is documented in the upper part of the Qasim Formation (cores 49-56) and in the deeper core samples referred to the lower part of the Sarah Formation (cores 45-47 from the disrupted facies of the Sarah Sandstone Member). It contains abundant and well-preserved Armoricochitina nigerica and Ancyrochitina merga associated with e.g., Euconochitina lepta, Calpichitina lenticularis, A. barbata and Desmochitina typica. In addition to these classical components, new species have been observed. This assemblage occurring in pre-glacial as well as in glacially related strata is assigned to the late Katian-earliest Hirnantian (Ashgill). The overlying productive interval, corresponding to the Baq'a Shale Member, is less productive and sometimes virtually barren of chitinozoans. This interval yields a third assemblage mainly composed of broken specimens of Angochitina cf. curvata, C. lenticularis, Cyathochitina sp., D. typica, F. spinifera, Tanuchitina fistulosa, Euconochitina gr. lepta, and even Siphonochitina formosa. Most of these forms are interpreted as glacially reworked. The youngest assemblage is restricted to three samples (core 27), which are located very close to a Silurian gamma ray peak and above the highest evidence of glacial sediments represented by the Sarah Formation. This forth assemblage contains extremely abundant chitinozoans coexisting with a few graptolite remains and inarticulate brachiopods. This chitinozoan assemblage is dominated by Cyathochitina caputoi, which is associated with Belonechitina pseudarabiensis and subordinate numbers of Ancyrochitina and Euconochitina species. The classical Late Ordovician chitinozoan taxa are no longer present and an earliest Rhuddanian age is proposed.Carbon stable isotope (δ13Cchit.) values have been measured on picked chitinozoan vesicles from the upper part of the Quwarah Member (upper Qasim Formation) and from the basal part of the Qusaiba Member (Qalibah Formation) where they register a shift towards more negative values close to the Gamma ray peak. The timing of the Late Ordovician glaciation and correlation with Hirnantian glacial events recorded in Northern Gondwana regions are briefly discussed based on the recovered chitinozoans.Four new species, i.e., Conochitina rotundata sp. nov., Belonechitina tenuicomata sp. nov., Hercochitina multiansata sp. nov., and Calpichitina bernardae sp. nov. are described, discussed and illustrated. Biometric data are provided for Acanthochitina barbata and for Armoricochitina nigerica. © 2014 Elsevier B.V. Source


Breuer P.,Aramco Services Company | Miller M.A.,Irf Group Inc. | Leszczynski S.,Jagiellonian University | Steemans P.,University of Liege
Review of Palaeobotany and Palynology | Year: 2015

The Jauf Formation miospore succession is synthesized in terms of palaeoenvironments and sequence stratigraphy. The data set for this study is obtained from four overlapping, continuously cored, and extensively sampled, boreholes that form a 940. ft (287. m) composite section. The Jauf Formation ranges in age from late Pragian to latest Emsian. The palynological assemblages, recognized herein, provide the basis for recognizing depositional environments present in the Lower Devonian of northern Saudi Arabia. Transgressive-regressive cycles are indicated not only by lithology, but also by marked changes in the marine to terrestrially dominated palynological assemblages, which are described in detail. Flooding events are recognized by the replacement of spore-dominated assemblages by organic-walled microphytoplankton and could be climate-controlled. The maximum flooding interval for the Jauf Formation is reinterpreted based on a correlative event consisting of diverse acritarchs and abundant chitinozoans. The sequence of palynological assemblages corresponds to fourth order cycles in the Hammamiyat Member. The new northern Gondwanan biozonation developed by Breuer and Steemans (2013) and used here allows a high-resolution regional biozonation for the Arabian Plate and larger-scale correlation of the Jauf Formation with other Gondwanan and Euramerican localities. One new spore genus (. Zonohilates) and four new spore species (. Insculptospora maxima, Camarozonotriletes alruwailii, Devonomonoletes crassus and Zonohilates vulneratus) are proposed. © 2014 Elsevier B.V. Source


Wellman C.H.,University of Sheffield | Steemans P.,University of Liege | Miller M.A.,Irf Group Inc.
Review of Palaeobotany and Palynology | Year: 2015

Palynological analysis of a sequence of Upper Ordovician to lowermost Silurian sediments from the Qusaiba-1 core hole drilled in the Qasim region of central Saudi Arabia has yielded rich palynomorph assemblages. The palynomorphs are abundant, exceptionally well preserved and of low thermal maturity. The sequence represents marine sediments that encompass glacial deposits representing the end Ordovician (Hirnantian) glaciation. All of the palynomorph assemblages are dominated by marine elements (acritarchs, chitinozoans, scolecodonts), although land-derived spores are present in most assemblages and are often moderately abundant. There is clear evidence for reworking into some of the glacial deposits. The strata are tightly age constrained based on chitinozoan and acritarch biostratigraphy, in addition to graptolite biostratigraphy in the lowermost Silurian deposits. In this paper we systematically describe the spores and erect two new taxa: a cryptospore permanent tetrad Tetraplanarisporites laevigatus gen. et sp. nov. and a trilete spore Chelinospora prisca sp. nov. We discuss the biostratigraphical implications of these tightly age constrained spore assemblages and recognise the need to establish regional rather than global spore biostratigraphic schemes in the Ordovician-early Silurian. We also discuss the palaeobotanical implications of the spore assemblages. The presence of true trilete and hilate spores, some of which are ornamented, suggests that a clade of plants characterised by trilete/hilate spore production may have evolved earlier in Gondwana than elsewhere. We develop evolutionary and palaeophytogeographical hypotheses to explain this early occurrence of trilete and hilate spores. © 2014 Elsevier B.V. Source

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