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Palynological analyses of Eocene to Oligocene sediments from DSDP Site 338, Outer Voring Plateau
No full text(Appendix B) Dinoflagellate cysts occurrence in DSDP Hole 38-33
Unique preservation of siliceous dinoflagellate motile cells from the Oligocene fossil Lagerstatte of Sieblos, Germany
No full textThe Triassic to Recent fossil record of the dinoflagellates is represented overwhelmingly by geologically resistant, organic-walled, non-motile resting cysts; such cysts are formed following the sexual phase in the life cycle. Very few confirmed records exist of the motile stage being preserved in the fossil record. This paper reports the occurrence of two very unusual dinoflagellate taphofacies, one developed in bituminous shales and the other in micrites, from the Oligocene fossil Lagerstätte at Sieblos, Hesse, Germany. A new dinoflagellate taxon, Sieblososphaera martini sp. nov. has been identified through analysis of dissociated skeletal elements in the bituminous shales and external moulds and casts in the micrites. The unique preservation of these fossils confirms them not only as primary biogenically silicified motile thecate cells, but also indicates that there was a much greater range of tabulation present within the subfamily Lithoperidiniaceae than has hitherto been recognized.</p
Cretaceous (Hauterivian–Cenomanian) palaeoceanographic conditions in southeastern Tethys (Matruh Basin, Egypt): Implications for the Cretaceous climate of northeastern Gondwana
No full textQuantitative palynological, sedimentological, and geophysical data analyses of the Cretaceous Abu Tunis 1X well from the Matruh Basin, northwestern Egypt indicate deposition of four major alternating regressive–transgressive successions. Sedimentation was largely affected by the Tethyan 2nd order sea level changes, with minor overprints by regional tectonics. The Lower Cretaceous part of the succession shows regressive sequences of deltafront to delta-top (upper Hauterivian–lowermost upper Barremian), delta channel (upper Aptian–middle Albian), and distal deltaic (upper Albian) settings that were interrupted by transgressive inner–proximal middle shelf deposits (uppermost Barremian–middle Aptian). These sediment packages correspond to Tethyan sea level fall from the late Hauterivian to late Barremian, and to the early–middle Aptian long-term sea level high stand. The Tethyan late Aptian–middle Albian long-term (2nd order) sea level rise was masked by regional late Aptian–Albian uplift, which affected deposition of the later regressive sequence. The Cenomanian shows a change in depositional setting from a proximal inner shelf (lower Cenomanian) to a middle shelf setting (middle–upper Cenomanian), corresponding to the Tethyan long-term latest early–late Cenomanian sea level rise.We demonstrate that northeastern Gondwana (Egypt) experienced different climatic conditions from other parts of the Northern Gondwana Phytogeographic Province. The climate in Egypt shifted from less warm and more humid conditions of the Hauterivian–early Barremian to a warmer and drier climate during the late Barremian–middle Aptian, although never becoming as dry as western Northern Gondwana. Warmer and more humid conditions were reestablished during the late Aptian and became even more accentuated during the Albian–Cenomanian, in contrast to the warm and much drier climate of Northern Gondwana at that time. Turonian climatic conditions may have been less humid as a result of the breakup of the Western Gondwanan supercontinent and the northeasterly drift of the African continent. The climatic conditions experienced in northeastern Gondwana developed through the early-mid Cretaceous as a result of changes in palaeolatitudinal position, variations in sea level, and shifts in the Intertropical Convergence Zone, which drove fluctuations between periods of warm humid and warm dry conditions
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Cretaceous (Albian–?early Santonian) palynology and stratigraphy of the Abu Tunis 1x borehole, northern Western Desert, Egypt
No full textA palynological analysis has been conducted on the Cretaceous sediments of the Abu Tunis 1x borehole, in the northern Western Desert, Egypt. The palynomorphs recovered have been analysed both qualitatively and quantitatively, and permit a refinement of the original stratigraphy with the identification of four time-rock units. These have been divided into four informal sporomorph units and one dinoflagellate cyst palynozone. These biozones are, from oldest to youngest: the Afropollis jardinus-Tricolporopollenites-Elaterosporites klaszii Assemblage Zone (early–mid Albian), the Elaterosporites verrucatus-Sofrepites legouxae-Cretacaeiporites Assemblage Zone (late Albian–early Cenomanian), the Sofrepites legouxae Partial Range Zone (early–?mid Cenomanian), the Proteacidites cf. africaensis Total Range Zone (mid–late Cenomanian) and the Canningia senonica Total Range Zone (early? Santonian). A barren interzone has been identified immediately below the youngest palynozone, and this may be related to the unfavourable lithology (i.e., limestone and dolostone). The absolute abundances of spores and pollen represent the first quantitative description of an Egyptian Albian–Cenomanian palynofloral, a flora that is characteristic of the Albian–Cenomanian Elaterate Phytogeographical Province. The early Santonian palynoflora is exclusively marine phytoplankton; terrestrial palynomorphs representative of the Senonian Palmae Province are completely absent. The quantitative and semi-quantitative distributions of Afropollis jardinus are compared with similar semi-quantitative distributions of this species from other wells in the northern Western Desert of Egypt, and this permitted the identification of a mid Albian–early Cenomanian Afropollis jardinus ‘acme’ as an important local biostratigraphical event in the mid Cretaceous
Early Cretaceous palynostratigraphy of the Abu Tunis 1x borehole, northern Western Desert, Egypt, with emphasis on the possible palaeoclimatic effect upon the range of Dicheiropollis etruscusin North Africa
No full textRecent hydrocarbon exploration in the northern sector of the Western Desert in Egypt has revealed relatively rich hydrocarbon accumulations, mainly of gas, and demonstrate promising future prospects. In order to improve our understanding of this area and to provide a biostratigraphical framework for the hitherto poorly dated Lower Cretaceous successions, a palynological analysis was carried out on 57 ditch cutting samples from the Abu Tunis 1x borehole. Palynostratigraphic investigation on these samples has enabled the identification of three new palynostratigraphically defined age divisions with three corresponding palynozones defined by first uphole occurrences of gymnosperm and angiosperm pollen and dinoflagellate cysts. Spore and pollen grains recovered from the Abu Tunis 1x borehole show the characteristics of the pre-Albian Dicheiropollis/Afropollis Phytogeographical Province. Discrepancies in the reported range of Dicheiropollis etruscus, when compared with earlier (Berriasian) appearances in West Africa and later (late Hauterivian) appearances in East Africa, may be attributed to palaeoecological factors. Dicheiropollis etruscus is accepted as having a cheirolepidiacean conifer affinity and is regarded as having been produced by a thermophilous plant. Here, we suggest that Dicheiropollis etruscus was adapted to arid conditions. Dicheiropollis etruscus thus first appeared in hot, dry palaeo-subtropical African regions, but as Western Gondwana broke up and the African Plate moved northeast during/after the Late Jurassic, the region that is now present-day Egypt, Libya and Sudan had moved by the late Hauterivian into a subtropical position; the ensuing increased aridity thus allowed Dicheiropollis etruscus to migrate into these areas
A new high northern latitude dinocyst-based magneto-biostratigraphic calibration for the Norwegian-Greenland Sea
No full textA refined dinoflagellate cyst biostratigraphy has been developed for the Oligocene successions from two high latitude Northern Hemisphere sites from the Norwegian-Greenland Sea (i.e., Ocean Drilling Program Leg 162, Hole 985A and Leg 151, Hole 908A), and this has been calibrated to newly developed magnetic polarity stratigraphies for both sites. These two new stratigraphic schemes provide important new temporal and spatial frameworks for understanding high latitude climate variability during the transition from greenhouse to icehouse climate states. We show that several of the dinoflagellate cyst marker events used in mid-latitudes stratigraphies (e.g., Distatodinium biffii, Saturnodinium pansum, Artemisiocysta cladodichotoma) demonstrate diachroneity at the high latitude sites. We hypothesize that this diachroneity is due to increased meridional thermohaline gradients related to oceanographic gateway evolution and/or cooling of the Northern Hemisphere high latitudes during the Oligocene. Furthermore, we are able to more accurately constrain the age and duration of a major hiatal surface found in many northern high latitude locations, confirming the regional nature of this hiatal surface and dating it from the late Oligocene to mid-Miocene
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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