The role of hydrothermal activity in the formation of karst-hosted manganese deposits of the Postmasburg Mn Field, Northern Cape Province, South Africa

The Postmasburg Manganese Field (PMF), Northern Cape Province, South Africa, once represented one of the largest sources of manganese ore worldwide. Two belts of manganese ore deposits have been distinguished in the PMF, namely the Western Belt of ferruginous manganese ores and the Eastern Belt of siliceous manganese ores. Prevailing models of ore formation in these two belts invoke karstification of manganese-rich dolomites and residual accumulation of manganese wad which later underwent diagenetic and low-grade metamorphic processes. For the most part, the role of hydrothermal processes and metasomatic alteration towards ore formation has not been adequately discussed. Here we report an abundance of common and some rare Al-, Na-, K- and Ba-bearing minerals, particularly aegirine, albite, microcline, banalsite, sérandite-pectolite, paragonite and natrolite in Mn ores of the PMF, indicative of hydrothermal influence. Enrichments in Na, K and/or Ba in the ores are generally on a percentage level for most samples analysed through bulk-rock techniques. The presence of As-rich tokyoite also suggests the presence of As and V in the hydrothermal fluid. The fluid was likely oxidized and alkaline in nature, akin to a mature basinal brine. Various replacement textures, particularly of Na- and K- rich minerals by Ba-bearing phases, suggest sequential deposition of gangue as well as ore-minerals from the hydrothermal fluid, with Ba phases being deposited at a later stage. The stratigraphic variability of the studied ores and their deviation from the strict classification of ferruginous and siliceous ores in the literature, suggests that a re-evaluation of genetic models is warranted. New Ar-Ar ages for K-feldspars suggest a late Neoproterozoic timing for hydrothermal activity. This corroborates previous geochronological evidence for regional hydrothermal activity that affected Mn ores at the PMF but also, possibly, the high-grade Mn ores of the Kalahari Manganese Field to the north. A revised, all-encompassing model for the development of the manganese deposits of the PMF is then proposed, whereby the source of metals is attributed to underlying carbonate rocks beyond the Reivilo Formation of the Campbellrand Subgroup. The main process by which metals are primarily accumulated is attributed to karstification of the dolomitic substrate. The overlying Asbestos Hills Subgroup banded iron formation (BIF) is suggested as a potential source of alkali metals, which also provides a mechanism for leaching of these BIFs to form high-grade residual iron ore deposits

Sediment routing and recycling through multiple basins from Palaeozoic to Mesozoic times: a provenance study of the Devonian Old Red Sandstone of southern Ireland and neighbouring offshore Mesozoic basins

This study presents the first dataset of detrital zircon U-Pb ages from the Devonian Old Red Sandstone (ORS) in the Dingle and Munster Basins as well as the offshore Mesozoic North Celtic Sea Basin (NCSB), South Celtic Sea Basin (SCSB), Goban Spur Basin (GSB) and Fastnet Basin (FB). This large dataset is complimented by new detrital white mica Ar-Ar ages in both onshore and offshore basins as well as apatite U-Pb ages in the Dingle and Munster Basins. Previous work (Ennis et al., 2015; Soper and Woodcock, 2003) has indicated the possibility of recycling of Lower ORS (LORS) into the Upper ORS (UORS) due to mid-Devonian Acadian deformation and basin inversion. By exploring the possible sediment sources for each basin, the study aims to investigate the role of recycling in sediment provision to answer two main questions: 1)Does the UORS in southern Ireland represent large-scale recycling of LORS from the Dingle Basin? 2)Does the southern Irish ORS act as a major source of detritus for Triassic to Cretaceous sediments of the NCSB, SCSB, GSB and FB? Sedimentary rocks in the LORS have similar detrital zircon age distributions which are dominated by ca. 1.2 Ga zircons as well as late Neoproterozoic grains. These age distributions suggest a dominant contribution of detritus of Laurentian affinity as well as contributions from westerly and southerly derived Ganderian (peri-Gondwanan) detritus. Caledonian uplift of the area north of the Iapetus Suture would have allowed for a large contribution of Laurentian material. The majority of UORS samples contain very few late Neoproterozoic grains and are instead dominated by early Palaeozoic and ca. 1.1 Ga zircons. These detrital zircon age distributions represent recycling of northerly-derived Ordovician to Silurian sedimentary rocks of the Southern Uplands – Longford Down terrane, which are of Laurentian affinity, and not recycling of LORS as previously suggested. The western Toe Head and Old Head Sandstone Formations, which represent the transition from terrestrial ORS to Carboniferous marine environments, are dominated by zircons of Acadian (410-390 Ma) age as well as late Neoproterozoic zircons, suggesting a western offshore Acadian granite source. Clastic rocks of the eastern Old Head Sandstone Formation have a Laurentian provenance like that of the underlying UORS. Detrital apatite and white micas from the ORS indicate Late Caledonian (430-420 Ma) to Acadian sources which were generally not recorded by detrital zircon ages. The majority of samples in the offshore basins of southern Ireland have complex detrital zircon age distributions which indicate a mixture of sources. Most samples contain an abundance of late Neoproterozoic zircons of peri-Gondwanan affinity. Potential candidates for these zircons include Ganderia, Megumia, Avalonia and Cadomia but distinguishing between these is problematic – especially given the likely mixture of sources. The abundance of late Mesoproterozoic detrital zircons in some samples indicates the presence of a Laurentian source with the most likely delivery method for such zircons being recycling of UORS sedimentary rocks, simply due to their close proximity (forming the footwall to the NCSB) to the Mesozoic basins. Two detrital white mica samples have dominant Late Caledonian (~430 Ma) ages, one sample has mostly Acadian (~405 Ma) and one sample has a dominant late Neoproterozoic age. Thus, sediments in the southern Irish offshore basins were predominantly sourced from peri-Gondwanan terranes, Caledonian and Acadian granites and recycling of UORS sedimentary rocks

Reliability in the whole life cycle of building systems

Purpose – The purpose of this research is to show that reliability analysis and its implementation will lead to an improved whole life performance of the building systems, and hence their life cycle costs (LCC). Design/methodology/approach – This paper analyses reliability impacts on the whole life cycle of building systems, and reviews the up-to-date approaches adopted in UK construction, based on questionnaires designed to investigate the use of reliability within the industry. Findings – Approaches to reliability design and maintainability design have been introduced from the operating environment level, system structural level and component level, and a scheduled maintenance logic tree is modified based on the model developed by Pride. Different stages of the whole life cycle of building services systems, reliability-associated factors should be considered to ensure the system's whole life performance. It is suggested that data analysis should be applied in reliability design, maintainability design, and maintenance policy development. Originality/value – The paper presents important factors in different stages of the whole life cycle of the systems, and reliability and maintainability design approaches which can be helpful for building services system designers. The survey from the questionnaires provides the designers with understanding of key impacting factors

Mouse models of preterm birth: Suggested assessment and reporting guidelines

Preterm birth affects approximately 1 out of every 10 births in the United States, leading to high rates of mortality and long-term negative health consequences. To investigate the mechanisms leading to preterm birth so as to develop prevention strategies, researchers have developed numerous mouse models of preterm birth. However, the lack of standard definitions for preterm birth in mice limits our field\u27s ability to compare models and make inferences about preterm birth in humans. In this review, we discuss numerous mouse preterm birth models, propose guidelines for experiments and reporting, and suggest markers that can be used to assess whether pups are premature or mature. We argue that adoption of these recommendations will enhance the utility of mice as models for preterm birth

Effect of interventions including provision of personalised cancer risk information on accuracy of risk perception and psychological responses: A systematic review and meta-analysis.

OBJECTIVE: To synthesize the literature on the effect of provision of personalised cancer risk information to individuals at population level risk on accuracy of risk perception and psychological responses. METHODS: A systematic review and random effects meta-analysis of articles published from 01/01/2000 to 01/07/2017. RESULTS: We included 23 studies. Immediately after provision of risk information 87% of individuals were able to recall the absolute risk estimate. Less than half believed that to be their risk, with up to 71% believing their risk to be higher than the estimate. Provision of risk information increased accuracy of perceived absolute risk immediately after risk information compared with no information (pooled RR 4.16 (95%CI 1.28-13.49), 3 studies). There was no significant effect on comparative risk accuracy (pooled RR 1.39 (0.72-2.69), 2 studies) and either no change or a reduction in cancer worry, anxiety and fear. CONCLUSION: These findings highlight the complex cognitive processes involved in the conceptualisation of risk. PRACTICE IMPLICATIONS: Individuals who appear to understand and are able to recall risk information most likely do not believe it reflects their own risk.JUS is funded by a Cancer Research UK Cancer Prevention Fellowship (C55650/A21464). BS was supported by the Medical Research Council [MC_UU_12015/4]. SJS is supported by the Medical Research Council www.mrc.ac.uk [Unit Programme number MC_UU_12015/1]. The University of Cambridge has received salary support in respect of SJG from the NHS in the East of England through the Clinical Academic Reserve

2017 SFU Liaison Librarian Program Evaluation Survey

As the SFU Library Liaison Program continues to evolve in response to Library and University priorities, this brief survey is one element in a multi-faceted, continual evaluation process that intends to provide a snapshot of the overall program from the liaison librarians\u27 perspective, as well as to identify 1) areas of success, 2) issues that require further investigation, and 3) new areas of growth emerging in the work.This 23 question survey was distributed online using FluidSurveys to SFU liaison librarians (departmental and functional) in May 2017. Not all questions were mandatory, and librarians were told that their responses would remain anonymous. We received a total of 24 responses to the survey, 21 of which were complete