Trace Element and Isotopic Variations in Scottish and Irish Dinantian Volcanism: Evidence for an OIB-like Mantle Source

The Dinantian volcanic province of southern Scotland, northernEngland and parts of Ireland is represented by a large volumeof transitional to mildly alkaline rocks. Many (although notall) of its basic members display inter-regional variationsin incompatible element concentrations, particularly LREE, Zr,Nb, K, and Ba. Sr, Nd, and Pb isotopic data also show some minorinter-regional variations, although they are not as well-definedas those observed in the trace elements. Indeed, much of thevariation is intra-regional. Modelling of the basic rocks (4%MgO) using Ce/Y and Zr/Nb ratios reveals that fractional crystallizationand varying degrees of partial melting alone cannot explainthe compositional diversity. Models involving variable-depthmelting in the stability fields of both garnet and spinel, andgarnet exhaustion through progressive melting are equally untenable.The best model to fit the ratios is one involving variable-degreemelting superimposed on slight source region heterogeneity. Investigations of potential magma sources suggest that thisheterogeneity is not related to crustal contamination or toincorporation of relict slab material derived from a pre-existingsubduction zone (c. 50 Ma earlier) in the same region. Instead,the observed trace element and isotopic characteristics showmarked similarities to many modern ocean island basalts (OIB):a feature which suggests that the mantle source region was sub-lithospheric.It is suggested that the variations observed in basic Dinantianvolcanic rocks merely mirror on a local scale the variationsobserved in OIB globally, and that no other source is necessaryto explain the chemical diversity of Dinantian magmas. If thespeed of northward motion (15? of latitude between the LowerCarboniferous and Lower Permian) and the longevity of Dinantianvolcanism (c. 40 Ma) are taken into account, it is hardly surprisingthat such distinct chemical variations are observed: the magmasmay well have sampled an enormous volume of convecting sublithosphericmantle.     

Producer responsibility in a sustainable development context: ecological modernisation or industrial ecology?

The concept of producer responsibility has become a major tenet of EU waste management policy. It forms part of an effort to set a regulatory context for firms supportive of sustainable development. Two contrasting notions of the theory and implementation of sustainable development are ecological modernisation and industrial ecology. Ecological modernisation emphasises economic development and technological advances, within a suitable policy framework. Industrial ecology, by contrast, emphasises inter-firm cooperation and voluntary compliance inspired by eco-efficiency savings. Recently, however, industrial ecologists have shown greater interest in the potential for policy implementation. With aims such as increasing recovery of value from waste, creating a demand for recycled materials, and decreasing the potential harmful effects of waste, the producer responsibility directives can be seen as attempts to implement industrial ecology principles. This paper examines interrelationships of ecological modernisation and industrial ecology to understand the potential and shortcomings of the producer responsibility regulations as a means to promote waste minimisation through eco-design.     

The Koloa Volcanic Suite of Kauai, Hawaii

The Koloa lavas of the post-erosional volcanic suite of Kauaivary in composition from melilitite to alkali olivine basalt.⁸⁷Sr/⁸⁶Sr varies from {small tilde}0.7030 to 0.7033, the rangebeing similar to that of other Hawaiian post-erosional suites.The chemical composition within single lava flows is variableand forms major-element trends that are different from the mainKoloa trend. The main trend can be related to increased degreesof partial melting during decreasing pressure. The combinedevidence from Sr and Nd isotopes and rare earth elements (REEs)could suggest that an ocean island basalt (OIB) plume was infiltratedby a carbonate-rich melt with a high concentration of Sr andREEs derived from the mid-ocean ridge basalt (MORB) source.However, the Pb-isotope systematics of the Hawaiian islandsdo not suggest that a MORB source was involved during the generationof the posterosional lavas. Instead, we suggest that the Hawaiiantholeiitic and nephelinitic magma suites are derived from azoned plume with a low ⁸⁷Sr/⁸⁶Sr core and a high ⁸⁷Sr/⁸⁶Sr concentricmargin. The trends of the single flows and their variation inisotope ratios suggest that they formed from magmas accumulatedmainly from the central core of the zoned plume.