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Quaternary sequence stratigraphy of onshore Abu Dhabi Emirate
No full textGlacially driven eustatic sea-level fluctuations have left a clear signature only along the coastal regions and barrier islands of the Abu Dhabi Emirate. Four marine sequences are identifiable although others are known to exist offshore. The stratigraphy is complicated by aeolian processes associated especially with the Shamal winds which have blown from the northwest to create dune fields that dominate the Quaternary sedimentation. Whilst aeolian facies can clearly be identified separating marine incursions along the coastal regions, aeolian deflation has complicated the stratigraphy by recycling sediment partly in response to loss of windward sediment sources during marine transgressions and partly in response to glacially driven climatic changes. Unravelling the sequence stratigraphy of the desert dunes inland, especially beyond the coastal sabkhas, is therefore extremely difficult. The late Quaternary aeolian dunes and their veneer of mobile aeolian sands are grouped into a single poorly defined formation which spans the entire timescale of the sequences identified along the coast
Carbonate sedimentation around Jebel Dhanna: models for parts of the buried Holocene sabkha sequences elsewhere along the Abu Dhabi coastline
No full textThe early Holocene mainland coast of Abu Dhabi Emirate consisted of a series of embayments between headlands of Miocene inliers and Pleistocene carbonate seif dunes. Subsequently, most of those embayments were back-filled to form coastal sabkhas. The facies and gross depositional characteristics of modern embayments adjacent to Jebel Dhanna are described and used as analogues for former embayments such as those landward of Abu Dhabi Island. Unfortunately, the sedimentology of both modern and earlier embayments have been severely or completely destroyed by industrial and urban developments but vintage aerial photography and satellite imagery have revealed the former topography.</p
Giant burrows in the Quaternary Limestones of Futaysi Island and Al Dabb'iya, Abu Dhabi Emirate
No full textPleistocene carbonates along the northern coasts of Futaysi Island and Al Dabb'iya tombolo, Abu Dhabi, U.A.E., contain unusual calcirudite-filled structures which are bowl- and funnel-shaped in vertical section; roughly circular in plan view; up to 1 m in diameter and 1 m deep. The calcirudite infill is dominated by clasts of reworked lithified smaller burrows and what appear to be fragments of beach rock or hardground. These structures were previously interpreted as marking the sites of former trees with holes, left behind by their root balls, infilled by a storm deposit and were considered to indicate an emergent event marking the boundary between two Pleistocene sedimentary sequences represented by the Futaisi (Futaysi) and Dabb’iya Members of the Fuwayrit Formation. However, they are here re-interpreted as giant burrows formed by some, as yet, unknown marine animal probably foraging for food or using them as dwelling sites which contained storm deposits emplaced in shallow water. Thin crusts on top of some giant burrow infills possibly suggest emergence and this would require a repositioning of the sequence boundary between the Futaysi and Dabb’iya Members. The burrows are believed to have been formed at approximately 75–125 Ka.<br/
Eustatic control of late Quaternary sea-level change in the Arabian/Persian Gulf
No full textAccurate sea-level reconstruction is critical in understanding the drivers of coastal evolution. Inliers of shallow marine limestone and aeolianite are exposed as zeugen (carbonate-capped erosional remnants) on the southern coast of the Arabian/Persian Gulf. These have generally been accepted as evidence of a eustatically driven, last-interglacial relative sea-level highstand preceded by a penultimate glacial-age lowstand. Instead, recent optically stimulated luminescence (OSL) dating suggests a last glacial age for these deposits, requiring > 100 m of uplift since the last glacial maximum in order to keep pace with eustatic sea-level rise and implying the need for a wholesale revision of tectonic, stratigraphic and sea-level histories of the Gulf. These two hypotheses have radically different implications for regional neotectonics and land–sea distribution histories. Here we test these hypotheses using OSL dating of the zeugen formations. These new ages are remarkably consistent with earlier interpretations of the formations being last interglacial or older in age, showing that tectonic movements are negligible and eustatic sea-level variations are responsible for local sea-level changes in the Gulf. The cause of the large age differences between recent studies is unclear, although it appears related to large differences in the measured accumulated dose in different OSL samples
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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