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    ABSTRACT: Ocean drilling provides a global record of deposits throughout the oceans. An international collaborative ocean research program was established in 1966, and the International Ocean Discovery Program (IODP) is the most recent manifestation of this. During each expedition a large amount of data are generated and collected by the shipboard science team. It could be suggested that due to the different staff and objectives during each expedition there would be significant variations in the consistency of data recorded in the shipboard visual core descriptions (VCDs). Use of shipboard VCD data in a global study of volcanism through time required the ground truthing of VCD data, to assess the consistency of ash layer reporting and to identify the amount of under/over recording of volcanic ash layers in cores. Approximately 1400 ash layers in DSDP, ODP, IODP and JAMSTEC cores were examined and it was found that on average 70-75% of recorded volcanic ash layers were present as described, an average of 17-20% were over recorded and 10-15% were under recorded. A number of factors could contribute to this variability, such as VCD format, lack of time for shipboard sampling of every ash layer, significant ash layer colour changes since time of coring, or differences in VCD recording and volcanic ash layer identification and description schemes between expeditions. These findings are important and will allow greater confidence in further studies based on data compiled from shipboard VCDs.
    Full-text · Article · Nov 2014 · Marine Geology
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    ABSTRACT: Volume estimates of the 1815 Tambora eruption were re-analysed using new ash thickness data and new methods, giving a range of possible volumes for the different eruption phases. Volume calculations include ash fall extrapolation and caldera size approximations, as well as volume estimates from mass eruption rates and eruption duration, to find the most likely range of volumes consistent with the different methods and possible eruption dynamics. The results give a total volume of about 41 ± 4 km3 DRE, made of 23 ± 3 km3 DRE ash fall and 18 ± 6 km3 DRE pyroclastic flows. The ash fall volume can be further divided into 11 ± 2 km3 DRE Plinian ash fall and 12 ± 4 km3 DRE co-ignimbrite, making the Plinian ash fall larger than previously assumed, and more intense due to a higher mass eruption rate of 2 x 109 kg/s.
    No preview · Article · Oct 2014 · Journal of Volcanology and Geothermal Research
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    ABSTRACT: Since the discovery of the basal sauropodomorph dinosaur Thecodontosaurus in the 1830s, the associated fauna from the Triassic fissures at Durdham Down (Bristol, UK) has not been investigated, largely because the quarries are built over. Other fissure sites around the Bristol Channel show that dinosaurs represented a minor part of the fauna of the Late Triassic archipelago. Here we present data on microvertebrates from the original Durdham Down fissure rocks, which considerably expand the taxonomic diversity of the island fauna, revealing that it was dominated by the sphenodontian Diphydontosaurus, and that archosauromorphs, including sphenosuchian crocodylomorphs, coelophysoid theropods, and the basal sauropodomorph Thecodontosaurus, were diverse. Importantly, a few fish teeth provide new information about the debated age of the fissure deposit, which is identified as lower Rhaetian. Thecodontosaurus had been assigned an age range over 20–25 Myr of the Late Triassic, so this narrower age determination (209.5–204 Myr) is important for studies of early dinosaurian evolution.
    Full-text · Article · Jul 2014 · Proceedings of the Geologists Association
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