Themes, iteration and recoverability in action research

This paper develops three concepts important to the practice of action research recoverability, research themes, and iteration by highlighting their applicability beyond single action research studies. The concepts are discussed against a program of action research, undertaken by a multidisciplinary research team, with a research focus on local, sector and national evels. This contrasts with the more usual pattern of action research in single situations. Action research is criticized on the grounds that it lacks generalizability and external validity from one-off studies. Goodness criteria have been derived to address these and other criticisms. The recoverability criterion, less strong than the repeatability of experimentation, is central to these. A second concept, that of research themes, links the recoverability criterion and iteration in action research. Iteration within and between projects and the notion of critical mass, of doing work in more than one setting, address the limitations of single setting studies

Soft systems methodology: other voices

This issue of Systemic Practice and Action Research, celebrating the work of Peter Checkland, in the particular nature and development of soft systems methodology (SSM), would not have happened unless the work was seen by others as being important. No significant contribution to thinking happens without a secondary literature developing. Not surprisingly, many commentaries have accompanied the ongoing development of SSM. Some of these are insightful, some full of errors, and some include both insight and absurdity. Checkland (1999, p. A42) opines, in the recently published 30-year retrospective, that "SSM has been ill-served by its commentators." Scrutiny of the secondary literature on SSM provides support for this view and also identifies some general characteristics and trends that are important to the development of SSM and, incidentally, reinforces some existing conclusions

The application of S isotopes and S/Se ratios in determining ore-forming processes of magmatic Ni–Cu–PGE sulfide deposits: a cautionary case study from the northern Bushveld Complex

The application of S/Se ratios and S isotopes in the study of magmatic Ni–Cu–PGE sulfide deposits has long been used to trace the source of S and to constrain the role of crustal contamination in triggering sulfide saturation. However, both S/Se ratios and S isotopes are subject to syn- and post-magmatic processes that may alter their initial signatures. We present in situ mineral δ34S signatures and S/Se ratios combined with bulk S/Se ratios to investigate and assess their utility in constraining ore-forming processes and the source of S within magmatic sulfide deposits. Magmatic Ni–Cu–PGE sulfide mineralization in the Grasvally Norite–Pyroxenite–Anorthosite (GNPA) member, northern Bushveld Complex was used as a case study based on well-defined constraints of sulfide paragenesis and local S isotope signatures. A crustal δ34S component is evident in the most primary sulfide assemblage regardless of footwall lithology, and is inferred that the parental magma(s) of the GNPA member was crustally contaminated and sulfide saturated at the time of emplacement. However, S/Se ratios of both the primary and in particular secondary sulfide assemblages record values within or below the mantle range, rather than high crustal S/Se ratios. In addition, there is a wide range of S/Se ratio for each sulfide mineral within individual assemblages that is not necessarily consistent with the bulk ratio. The initial crustal S/Se ratio is interpreted to have been significantly modified by syn-magmatic lowering of S/Se ratio by sulfide dissolution, and post-magmatic lowering of the S/Se ratio from hydrothermal S-loss, which also increases the PGE tenor of the sulfides. Trace element signatures and variations in Th/Yb and Nb/Th ratios support both an early pre-emplacement contamination event as seen by the S isotopes and S/Se ratios, but also a second contamination event resulting from the interaction of the GNPA magma with the local footwall country rocks at the time of emplacement; though this did not add any additional S. We are able to present an integrated emplacement and contamination model for the northern limb of the Bushveld Complex. Although the multitude of processes that affect variations in the δ34S signature and in particular S/Se ratio may be problematic in interpreting ore genesis, they can reveal a wealth of additional detail on a number of processes involved in the genetic history of a Ni–Cu–PGE deposit in addition to crustal contamination. However, a prerequisite for being able to do this is to utilize other independent petrological and mineralogical techniques that provide constraints on both the timing and effect of various ore-forming and modifying processes. Utilizing both bulk and in situ methods in concert to determine the S/Se ratio allows for the assessment of multiple sulfide populations, the partitioning behaviour of Se during sulfide liquid fractionation and also the effects of low temperature fluid alteration. In comparison, S isotopes are relatively more robust and represent a more reliable indicator of the role of crustal S contamination. The addition of trace element data to the above makes for an incredibly powerful approach in assessing the role of crustal contamination in magmatic sulfide systems

Pore geometry as a control on rock strength

This study was funded via RJW's University of Leicester start-up fund, as part of AAB's PhD project. We thank Don Swanson and Mike Poland at HVO, Hawai'i, for their help and advice during fieldwork planning and sample collection in the Koa'e fault system, and the National Park Service for granting a research permit to collect rock samples. Sergio Vinciguerra is thanked for access to the Rock Mechanics and Physics lab at the British Geological Survey and Audrey Ougier-Simonin is thanked for her help preparing samples and advice during testing. We thank Mike Heap (EOST Strasbourg) and an anonymous reviewer for their detailed and careful comments that greatly improved the manuscript.Peer reviewedPostprin

Magmatic Cu-Ni-PGE-Au sulfide mineralisation in alkaline igneous systems: An example from the Sron Garbh intrusion, Tyndrum, Scotland

Magmatic sulfide deposits typically occur in ultramafic-mafic systems, however, mineralisation can occur in more intermediate and alkaline magmas. Sron Garbh is an appinite-diorite intrusion emplaced into Dalradian metasediments in the Tyndrum area of Scotland that hosts magmatic Cu-Ni-PGE-Au sulfide mineralisation in the appinitic portion. It is thus an example of magmatic sulfide mineralisation hosted by alkaline rocks, and is the most significantly mineralised appinitic intrusion known in the British Isles. The intrusion is irregularly shaped, with an appinite rim, comprising amphibole cumulates classed as vogesites. The central portion of the intrusion is comprised of unmineralised, but pyrite-bearing, diorites. Both appinites and diorites have similar trace element geochemistry that suggests the diorite is a more fractionated differentiate of the appinite from a common source that can be classed with the high Ba-Sr intrusions of the Scottish Caledonides. Mineralisation is present as a disseminated, primary chalcopyrite-pyrite-PGM assemblage and a blebby, pyrite-chalcopyrite assemblage with significant Co-As-rich pyrite. Both assemblages contain minor millerite and Ni-Co-As-sulfides. The mineralisation is Cu-, PPGE-, and Au-rich and IPGE-poor and the platinum group mineral assemblage is overwhelmingly dominated by Pd minerals; however, the bulk rock Pt/Pd ratio is around 0.8. Laser ablation analysis of the sulfides reveals that pyrite and the Ni-Co-sulfides are the primary host for Pt, which is present in solid solution in concentrations of up to 22 ppm in pyrite. Good correlations between all base and precious metals indicate very little hydrothermal remobilisation of metals despite some evidence of secondary pyrite and PGM. Sulfur isotope data indicate some crustal S in the magmatic sulfide assemblages. The source of this is unlikely to have been the local quartzites, but S-rich Dalradian sediments present at depth. The generation of magmatic Cu-Ni-PGE-Au mineralisation at Sron Garbh can be attributed to post-collisional slab drop off that allowed hydrous, low-degree partial melting to take place that produced a Cu-PPGE-Au-enriched melt, which ascended through the crust, assimilating crustal S from the Dalradian sediments. The presence of a number of PGE-enriched sulfide occurrences in appinitic intrusions across the Scottish Caledonides indicates that the region contains certain features that make it more prospective than other alkaline provinces worldwide, which may be linked the post-Caledonian slab drop off event. We propose that the incongruent melting of pre-existing magmatic sulfides or ‘refertilised’ mantle in low-degree partial melts can produce characteristically fractionated, Cu-PPGE-Au-semi metal bearing, hydrous, alkali melts, which, if they undergo sulfide saturation, have the potential to produce alkaline-hosted magmatic sulfide deposits

Cu-Ni-PGE mineralisation at the Aurora Project and potential for a new PGE province in the Northern Bushveld Main Zone

This is the final version of the article. Available from Elsevier via the DOI in this record.he Aurora Project is a Cu-Ni-PGE magmatic sulphide deposit in the northern limb of the Bushveld Complex of South Africa. Since 1992 mining in the northern limb has focussed on the Platreef deposit, located along the margin of the complex. Aurora has previously been suggested to represent a far-northern facies of the Platreef located along the basal margin of the complex and this study provides new data with which to test this assertion. In contrast to the Platreef, the base metal sulphide mineralisation at Aurora is both Cu-rich (Ni/Cu 50,000) reflecting the preferential removal of Pd over Cu in the sulphides below. Similarly high Cu/Pd ratios characterise the Upper Main Zone in the northern limb above the pigeonite + orthopyroxene interval and suggest that Aurora-style sulphide mineralisation may be developed here as well. The same mineralogy and geochemical features also appear to be present in the T Zone of the Waterberg PGE deposit, located under younger cover rocks to the north of Aurora. If these links are proved they indicate the potential for a previously unsuspected zone of Cu-Ni-PGE mineralisation extending for over 40 km along strike through the Upper Main Zone of the northern Bushveld.Sulphur isotope analyses were carried out by Alison MacDonald at the Scottish Universities Environmental Research Centre as part of NERC Isotope Geoscience Facilities Committee award IP/909/0506. HSRH is sponsored by the Claude Leon Foundation

Sulphide sinking in magma conduits: Evidence from mafic–ultramafic plugs on Rum and the wider North Atlantic Igneous Province

This is the final version of the article. Available from the publisher via the DOI in this record.Ni–Cu–PGE (platinum group element) sulphide mineralization is commonly found in magmatic conduit systems. In many cases the trigger for formation of an immiscible sulphide liquid involves assimilation of S-bearing crustal rocks. Conceptually, the fluid dynamics of sulphide liquid droplets within such conduits is essentially a balance between gravitational sinking and upwards entrainment. Thus, crustal contamination signatures may be present in sulphides preserved both up- and down-flow from the point of interaction with the contaminant. We examine a suite of ultramafic volcanic plugs on the Isle of Rum, Scotland, to decipher controls on sulphide accumulation in near-surface magma conduits intruded into a variable sedimentary stratigraphy. The whole-rock compositions of the plugs broadly overlap with the compositions of ultramafic units within the Rum Layered Complex, although subtle differences between each plug highlight their individuality. Interstitial base metal sulphide minerals occur in all ultramafic plugs on Rum. Sulphide minerals have magmatic δ34S (ranging from –1·3 to +2·1‰) and S/Se ratios (mean = 2299), and demonstrate that the conduit magmas were already S-saturated. However, two plugs in NW Rum contain substantially coarser (sometimes net-textured) sulphides with unusually light δ34S (–14·7 to +0·3‰) and elevated S/Se ratios (mean = 4457), not represented by the immediate host-rocks. Based on the Hebrides Basin sedimentary stratigraphy, it is likely that the volcanic con duits would have intruded through a package of Jurassic mudrocks with characteristically light δ34S (–33·8 to –14·7‰). We propose that a secondary crustal S contamination event took place at a level above that currently exposed, and that these sulphides sank back to their present position. Modelling suggests that upon the cessation of active magma transport, sulphide liquids could have sunk back through the conduit over a distance of several hundreds of metres, over a period of a few days. This sulphide ‘withdrawal’ process may be observed in other vertical or steeply inclined magma conduits globally; for example, in the macrodykes of East Greenland. Sulphide liquid sinking within a non-active conduit or during magma ‘suck-back’ may help to explain crustal S-isotopic compositions in magma conduits that appear to lack appropriate lithologies to support this contamination, either locally or deeper in the system.Sulphur isotope analyses were funded by NERC Isotope Geosciences Facilities grant, IP-1356-1112. H.S.R.H. acknowledges the financial support of the Natural Environment Research Council (NERC) for her PhD studentship (NE/J50029X) and funding of open access publication. This is a contribution to the TeaSe (Te and Se Cycling and Supply) research consortium supported by NERC award NE/M011615/1 to Cardiff University and the University of Leicester

Roles of magmatism, contamination and hydrothermal processes in the development of Platreef mineralization, Bushveld Complex, South Africa

The Platreef is a highly complex, pyroxenite-hosted Ni-Cu-PGE deposit. It is located at the base of the northern limb of the Bushveld Complex, South Africa, in direct contact with a variety of country rock sediments and Archaean basement. The interaction of the Platreef magma with these diverse country rock lithologies during emplacement had a profound effect on the style and distribution of the mineralization on both regional and local scales. Geometrically, the Platreef was emplaced as a thin, sill-like intrusion, with pre-formed PGE- rich sulfide droplets entrained within the magma. Sulfur saturation is likely to have occurred in a deep staging chamber or conduit prior to emplacement, and where immiscible sulfide droplets became enriched in PGE, base metals and semi metals. After emplacement, the PGE and semi-metal rich sulfide liquid cooled to form 'primary' assemblages of IPGE-rich pyrrhotite, IPGE-, Rh- and Pd-rich pentlandite, chalcopyrite, Pt and Pd tellurides and bismuthides and electrum within the feldspathic pyroxenites of the Platreef. Assimilation and metamorphism of some sedimentary footwall rocks, particularly the dolomites of the Malmani Subgroup, released large volumes of volatiles into the Platreef magma. This hydrothermal activity redistributed PGE and base metal sulfides (BMS) into the footwall rocks, and in places overprinted the 'primary' assemblages, and occasionally decoupled PGE from BMS, with the petrology of the reef and footwall, and the mineralogy of the platinum-group minerals, significantly affected. Each locality along the strike of the Platreef with a different footwall lithology has its own unique hydrothermal history directly related to the nature of the local floor rocks. For example, where the floor is composed of anhydrous basement gneiss, volatile activity was relatively insignificant, and partial melting of the floor allowed the percolation of PGE-rich sulfide liquid to penetrate the footwall. The nature of the floor rocks also controls the type and amount of contamination in the Platreef. Sulfides in country rock shales, for example, are assimilated into the Platreef magma and locally upgrade the S content at such localities, although this did not trigger S saturation. Footwall sulfates, such as anhydrite, cannot be assimilated, but can interact with the Platreef sulfides through hydrothermal leaching when sufficient fluids had been released during assimilation. After emplacement of the Platreef, a significant period of cooling occurred, such that the Platreef was almost completely crystallized, during which time some ductile deformation occurred. The gabbronoritic hangingwall magma was then emplaced, forming a magmatic unconformity over the Platreef, occasionally exploiting shear zones to intrude finger-like bodies down into the Platreef. Where the hangingwall magma assimilated mineralized Platreef thin zones of PGE mineralization developed at its base. The magmatic intrusion of the Platreef can be considered to be distinct from that of other magmatic units in the northern limb of the Complex. Its Ni-Cu-PGE sulfide mineralization is orthomagmatic in origin however, complex interaction with a variety of country rock lithologies has locally altered the style and distribution of the mineralization, to form unique mineralogical associations and assemblages along strike. The understanding of local country rock control on features such as the mineralogy of the ores and the extent of remobilization into the footwall is critical in optimizing exploration, mining and mineral processing techniques

Extension parallel to the rift zone during segmented fault growth: application to the evolution of the NE Atlantic

The mechanical interaction of propagating normal faults is known to influence the linkage geometry of first-order faults, and the development of second-order faults and fractures, which transfer displacement within relay zones. Here we use natural examples of growth faults from two active volcanic rift zones (Koa`e, island of Hawai`i, and Krafla, northern Iceland) to illustrate the importance of horizontal-plane extension (heave) gradients, and associated vertical axis rotations, in evolving continental rift systems. Second-order extension and extensional-shear faults within the relay zones variably resolve components of regional extension, and components of extension and/or shortening parallel to the rift zone, to accommodate the inherently three-dimensional (3-D) strains associated with relay zone development and rotation. Such a configuration involves volume increase, which is accommodated at the surface by open fractures; in the subsurface this may be accommodated by veins or dikes oriented obliquely and normal to the rift axis. To consider the scalability of the effects of relay zone rotations, we compare the geometry and kinematics of fault and fracture sets in the Koa`e and Krafla rift zones with data from exhumed contemporaneous fault and dike systems developed within a > 5×104 km2 relay system that developed during formation of the NE Atlantic margins. Based on the findings presented here we propose a new conceptual model for the evolution of segmented continental rift basins on the NE Atlantic margins

Egg Donation Brokers: An Analysis of Agency Versus in Vitro Fertilization Clinic Websites

Objective: To compare websites of agencies that broker the services of women who provide human eggs for in vitro fertilization versus clinics that recruit egg providers. Study design: We examined 207 websites, of which 128 were egg provider agency 40%) or clinic (60%) websites that recruited providers online. We compared them regarding several variables related to adherence to American Society for Reproductive Medicine (ASRM) guidelines. Results: According to their respective websites, agencies were more likely than clinics to mention ASRM guidelines, be located in the West/Pacific, indicate compensation, offer a fee range, set their minimum > $5,000, specify preferable traits, cap provider age at 31, require an education minimum, allow both parties to meet, discuss short-term risks, and not acknowledge a possible cancer risk. Only 25.5% of agencies and 19.5% of clinics mention psychological/emotional risks, and 11.8% and 5.2%, respectively, mention risk to future fertility. Conclusion: This research, the first to systematically compare several key aspects of egg provider agencies versus clinics, suggests it significant differences in adherence to guidelines, raising several concerns and suggesting needs for consideration of improved monitoring and regulation by ASRM or others