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Abstract

Balanomorph cirripedes from the Eocene–Oligocene of the Hampshire Basin (United Kingdom) and the Middle Eocene of the Cotentin Peninsula, Manche (France) are described. A new genus, Vectibalanus, is founded, with the type species Balanus unguiformis J. de C. Sowerby, 1846; assigned to this are also Balanus erisma J. de C. Sowerby, 1846 and Vectibalanus mortoni sp. nov. In addition, a new species of Lophobalanus Zullo, 1984, L. fresvillensis sp. nov., is described. This is the first record of that genus from outside the eastern USA and the oldest species known to date. Cladistic analysis of 24 morphological characters suggests that Vectibalanus unguiformis is sister taxon to a group comprising the most derived balanomorph taxa, and thus represents an important transition in the evolution of the group, with the initiation of development of a complex parietal wall structure. Vectibalanus unguiformis was evidently adapted to low salinity habitats (10–30 ppt), and is the oldest known brackish water barnacle. The other species ( V. erisma, V. mortoni sp. nov.) occupied more clearly marine environments (>30 ppt). Balanomorph barnacles appeared simultaneously in the Priabonian (Upper Eocene) of the Gulf and Atlantic seaboards of the USA and northwest Europe, which probably represents a northerly migration from Tethys.
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Authors and Affiliations

Andrew Scott Gale
1 2

  1. School of the Environment, Geography and Geological Sciences, University of Portsmouth, Burnaby Building, Burnaby Road, Portsmouth PO13QL, UK
  2. Department of Earth Sciences, Natural History Museum, Cromwell Road, London SW75BD, UK
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Abstract

The main optimized objects in underground mines include: stope layout, access layout and production scheduling. It is common to optimize each component sequentially, where optimal results from one phase are regarded as the input data for the next phase. Numerous methods have been developed and implemented to achieve the optimal solution for each component. In fact, the interaction between different phases is ignored in the tradition optimization models which only get the suboptimal solution compared to the integrated optimization model. This paper proposes a simultaneous integrated optimization model to optimize the three components at the same time. The model not only optimizes the mining layout to maximize the Net Present Value (NPV), but also considers the extension sequence of stope extraction and access excavation. The production capacity and ore quality requirement are also taken into account to keep the mining process stable in all mine life. The model is validated to a gold deposit in China. A two-dimensional block model is built to do the resource estimation due to the clear boundary of the hanging wall and footwall. The thickness and accumulation of each block is estimated by Ordinary Kriging (OK). In addition, the conditional simulation method is utilized to generate a series of orebodies with equal possibility. The optimal solution of optimization model is carried out on each simulated orebody to evaluate the influence of geological uncertainty on the optimal mining design and production scheduling. The risk of grade uncertainty is quantified by the possibility of obtaining the expected NPV. The results indicate that the optimization model has the ability to produce an optimal solution that has a good performance under the uncertainty of grade variability.

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Authors and Affiliations

Jie Hou
Guoqing Li
Nailian Hu
Hao Wang

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