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Mangakino, the oldest rhyolitic caldera centre delineated in the Taupo Volcanic Zone of New Zealand, generated two very large (super-sized) ignimbrite eruptions, the 1.21 ± 0.04 Ma >500 km3 Ongatiti and ~1.0 Ma ~1,200 km3 Kidnappers events, the latter

New zircon U-Th model-age and trace element datasets are presented fromTaupo volcano (New Zealand), which are used to investigate the timescales and broad-scale magmatic processes involving zircon crystallization after the caldera-forming 25·4 ka Oruanui

Crystallisation-age spectra have been obtained by SIMS techniques (SHRIMP-RG) on zircons from altered volcanic units penetrated by drillholes at Kawerau Geothermal Field in the central Taupo Volcanic Zone (TVZ), New Zealand. Drillholes penetrate 700-1300. m of volcanic rocks and sediments before reaching the basement Mesozoic greywacke. Twenty-seven samples of altered volcanic lithologies and two surficial, fresh rock units have been studied in order to constrain ages of the major stratigraphic units. Within the volcanic/sedimentary pile the oldest in-situ ignimbrites that can be widely correlated have ages of ~. 1.45. Ma. Between them and the basement greywacke is a variable thickness of sediments, mostly greywacke gravels and minor volcaniclastic units, reflecting localised basinal deposition associated with strike-slip faulting. Two ignimbrites within this sequence yield age estimates of c. 2.4 and 2.1. Ma, consistent with these being distal southern Coromandel Volcanic Zone deposits, pre-dating TVZ activity. Below the regional marker plane of the 0.32. Ma Matahina ignimbrite, three main ignimbrite groups occur, with ages around 1.45. Ma, 1.0. Ma and 0.6-0.5. Ma, which are separated by sediment-dominated intervals and andesite volcanics. All of these ignimbrites represent marker horizons from other volcanic centres and do not reflect the presence of local magmatic heat sources.Numerous bodies of coherent rhyolite, previous labelled as Caxton and Onepu rhyolites, have been intersected at all pre-Matahina ignimbrite levels (including within the basement greywacke) and reflect earlier local magmatic heat sources. Our geochronological data resolve these rock bodies into three packages. The youngest is represented by the surficial rhyodacite Onepu domes, 40Ar/39Ar dated at 0.138±0.007Ma. U-Pb ages on zircons from dome material yield a spectrum that can be matched (consistent with petrography) with two dikes intersected at 880m and 2.67km depth, and with an estimated a

There is lively debate on whether Asian plate material was involved in southward flow of mid-lower crust in a ductile channel beneath southern Tibet. One argument against such involvement is the apparent absence of material derived from Asian lithosphere within the High Himalayan Series (Indian plate) that could represent the putative channel. A north-south–trending mid-Miocene dike swarm that intrudes the Tethyan sedimentary cover of the Sakya gneiss dome (Indian plate) yields new Sr-Nd isotopic data (87Sr/86Sr = 0.7071–0.7079; Nd −4 to −6) indicating that these melts share the same source as Miocene dacitic dikes from north of the Indus-Tsangpo suture. Moreover, dikes on both sides of this suture represent crustal melts derived largely from mid-lower crust of the Asian plate, exposed today as the Nyainqentanglha gneisses that underlie the Gangdese batholith. We infer that melting of the Asian lithosphere extended south of the surface trace of the suture, requiring southward propagation of anatectic Asian middle crustal material during the Miocene. The emplacement ages of the southern dike swarm (12–9 Ma) thus delimit the timing of active southward ductile flow of Asian material.

This article reports the evaluation experience in two SOCRATES (European Union funding mechanism designed to support innovation in teaching and learning) projects focused on change in higher education. The projects were international in scope involving six countries and ten institutions within the last four years. The article reflects on change in institutions specifically, especially those introduced by the use of information and communication technologies, and it suggests the hypothesis that in such a phase of transition, new rules are not yet established and a state of anomie can occur at the level of courses, departments and institutions. The article details what happens in educational institutions in which rules and practices are well established and validated and a new event radically changes or challenges the traditional practices. Instead of the psycho-social notion of ‘resistance to change’, the theory of Durkheim and followers that analyses human responses in times of social change may be of use to interpret situations in which change or the will to change creates conflicting systems of rules and practices. The article will argue for a crucial role for evaluation in negotiating such periods of change.

This paper outlines the evaluation approach associated with the Learn-Nett project under the SOCRATES initiative. It describes the project, locates the role of evaluation within it and finally conceptualises the role evaluation might play in a change process. The paper argues that evaluation in these circumstances can be essentially formative but also be prompted by a search for new knowledge in the area of changing practices in learning. It identifies ‘transition’ as anomic and the need to develop ‘provisional stability’ for change to occur effectively. In such periods of change, evaluation products can act as useful ‘bridging tools’ which can support the development of ‘provisional stability’.