Palaeozoic volcanogenic mineral deposits at Parys Mountain, Avoca, and S.E. Canada: a comparative study. Available in 2 volumes.

The sulphide mineralisation at Avoca and Parys Mountain is intimately related to volcanism and is of volcanogenic sedimentary type. The associated volcanics are predominantly pyroclastics of rhyodacitic composition and of Upper Ordovician age. They were erupted from discrete small volcanic centres, products of single local volcanic events, whose spatial distribution was related to fractures in the sialic basement of the paratectonic Caledonides of the British Isles. These fractures resulted in linear controls on volcanic, plutonic and tectonic features; they are the result of predominantly strikeslip stresses generated in this part of the European plate during closure of the Iapetus ocean. The mineralisation, predominantly pyritic, consists of a siliceous footwall zone containing bedded and cross-cutting sulphides and an overlying non-siliceous zone of bedded sulphides which may show vertical zoning of metal ratios. The sulphides are associated with chert and iron formation and have been affected by slumping. Mineralisation developed near the vents during intense fumarolic activity accompanying strong volcanism; at Parys Mountain, fumarolic activity commenced prior to, and continued after, the rnain volcanic event. Comparison with similar deposits in Newfoundland and at Bathurst, in the Canadian Appalachians, shows that mineralisation can be associated with any discrete pulse of acid magmatism in shallow subaqueous conditions. Local features of the sulphides and associated sediments are similar, although in more distal deposits (with respect to a volcanic centre) footwall alteration and mineralisation are less well developed. The nature of the basement and the presence or absence of earlier volcanics are not critical, although establishment of a local tensional regime at the time of ore formation may be important. The volcanics hosting mineralisation are rhyodacitic pyroclastics, generally related to a small centre and representing a single episode of volcanism.

The metamorphic environments of the Strontian, Foyers and Dalbeattie intrusions, Scotland

Three metamorphic aureoles around intrusions of the Caledonian 'Newer Granite' suite are described. Each represents a different orogenic environment. The Strontian complex is intruded into sillimanite grade Moinian metasediments at the core of the orogen. The aureole comprises three zones; a transitional muscovite + sillimanite + K-feldspar zone, a sillimanite + K-feldspar zone and an inner cordierite + K-feldspar zone. Contact migmatization occurs in the inner part of the aureole. Zoning profiles from garnets in both regional and aureole assemblages show retrograde Mn-rich rims. Fe and Mg compositions are re-equilibrated to contact conditions. Apparent re-equilibration of Ca compositions results from increasingly ideal solid solution behaviour of Ca in plagioclase and garnet with increasing temperature. Temperatures of 690°C at 4.1 kbar (XH2O = 0.53) are estimated in the cordierite + K-feldspar zone, dropping to 630°C (XH2O = 0.69) at the sillimanite + K-feldspar isograd. The zones increase in width to the east, influenced by the regional thermal gradient at the time of intrusion. The timer-scale of the contact event, t2, relative to the regional, tl, - is estimated as t2/t1 = 101.1+ -0.7 and is consistent with Intrusion at an early stage of regional uplift and cooling. The Foyers complex intrudes Moinian rocks at a higher structural level. Regional assemblages range from garnet to sillimanite grade. Three contact zones are recognised; a sillimanite zone, a sillimanite + K-feldspar zone and an inner cordierite + K-feldspar zone. The limit of the aureole is marked by the breakdown of garnet which shows disequilibrium, both texturally, and in complex zoning profiles, within it. Temperatures of 660°C at 3.9 kbar (XH20 = 0.14) are estimated in the cordierite + K-feldspar zone? The Dalbeattie complex is at the margin of the orogen, intruded into low grade Silurian metasediments. Two zones are recognised; a biotite zone and an inner hornblende zone. Cordierite and diopside are present in the inner zone.

Planning the neighbourhood economy:land-use plans and the economic potential of urban residential neighbourhoods in the Netherlands

This article investigates the relationship between zoning by-laws, as put forward in governmental land-use plans and the viability of urban residential neighbourhood economies. The Dutch planning tradition has long been characterized by strict separation of functions and top-down planning. We argue that profound changes in social and economic structures make land-use planning practices less suitable for the current policy formula of "mixed urban milieus". Although the residential neighbourhood might not be the location of large firms, it definitely attracts small ones, and facilitates starting businesses whose presence (and potential growth) can be beneficial to the city as a whole. We present a typology of spatial patterns of neighbourhood economies based on land-use plans and describe whether these are related to the distinctive economic development of the neighbourhood over the period 1999-2007. © 2013 Taylor & Francis.