Magma Evolution in the Primitive, Intra-oceanic Tonga Arc: Petrogenesis of Basaltic Andesites at Tofua Volcano

Tofua volcano is situated midway along the Tonga oceanic arc and has undergone two phases of ignimbrite-forming activity. The eruptive products are almost entirely basaltic andesites (52 center dot 5-57 wt % SiO2) with the exception of a volumetrically minor pre-caldera dacite. The suite displays a strong tholeiitic trend with K2O <1 wt %. Phenocryst assemblages typically comprise plagioclase + clinopyroxene +/- orthopyroxene with microlites of Ti-magnetite. Olivine (Fo(83-88)) is rare and believed to be dominantly antecrystic. An increase in the extent and frequency of reverse zoning in phenocrysts, sieve-textured plagioclase and the occurrence of antecrystic phases in post-caldera lavas record a shift to dynamic conditions, allowing the interaction of magma batches that were previously distinct. Pyroxene thermobarometry suggests crystallization at 950-1200 degrees C and 0 center dot 8-1 center dot 8 kbar. Volatile measurements of glassy melt inclusions indicate a maximum H2O content of 4 center dot 16 wt % H2O, and CO2-H2O saturation curves indicate that crystallization occurred at two levels, at depths of 4-5 center dot 5 km and 1 center dot 5-2 center dot 5 km. Major and trace element models suggest that the compositions of the majority of the samples represent a differentiation trend whereby the dacite was produced by 65% fractional crystallization of the most primitive basaltic andesite. Trace element models suggest that the sub-arc mantle source is the residuum of depleted Indian mid-ocean ridge basalt mantle (IDMM-1% melt), whereas radiogenic isotope data imply addition of 0 center dot 2% average Tongan sediment melt and a fluid component derived from the subducted altered Pacific oceanic crust. A horizontal array on the U-Th equiline diagram and Ra excesses of up to 500% suggest fluid addition to the mantle wedge within the last few thousand years. Time-integrated (Ra-226/Th-230) vs Sr/Th and Ba/Th fractionation models imply differentiation timescales of up to 4500 years for the dacitic magma compositions at Tofua.

Magma Evolution in the Primitive, Intra-oceanic Tonga Arc: Rapid Petrogenesis of Dacites at Fonualei Volcano

Fonualei is unusual amongst subaerial volcanoes in the Tonga arc because it has erupted dacitic vesicular lavas, tuffs and phreomagmatic deposits for the last 165 years. The total volume of dacite may approach 5 km(3) and overlies basal basaltic andesite and andesite lavas that are constrained to be less than a few millennia in age. All of the products are crystal-poor and formed from relatively low-viscosity magmas inferred to have had temperatures of 1100-1000 degrees C, 2-4 wt % H2O and oxygen fugacities 1-2 log units above the quartz-fayalite-magnetite buffer. Major and trace element data, along with Sr-Nd-Pb and U-Th-Ra isotope data, are used to assess competing models for the origin of the dacites. Positive correlations between Sc and Zr and Sr rule out evolution of the within-dacite compositional array by closed-system crystal fractionation of a single magma batch. An origin by partial melting of lower crustal amphibolites cannot reproduce these data trends or, arguably, any of the dacites either. Instead, we develop a model in which the dacites reflect mixing between two dacitic magmas, each the product of fractional crystallization of basaltic andesite magmas formed by different degrees of partial melting. Mixing was efficient because the two magmas had similar temperatures and viscosities. This is inferred to have occurred at shallow (2-6 km) depths beneath the volcano. U-Th-Ra disequilibria in the basaltic andesite and andesite indicate that the parental magmas had fluids added to their mantle source regions less than 8 kyr ago and that fractionation to the dacitic compositions took less than a few millennia. The 165 year eruption period for the dacites implies that mixing occurred on a similar timescale, possibly during ascent in conduits. The composition of the dacites renders them unsuitable candidates as contributors to average continental crust.

(Re)-Introducing Themes of Religion and Spirituality to Professional Social Work Training in the Land of ‘Saints and Scholars’.

This chapter begins by alluding to Ireland’s historical reputation as the land of “Saints and Scholars” and then briefly charts its demise from this position. A parallel process in relation to religiously motivated provision of health and social care is outlined. The inclusion of themes of religion and spirituality within the current professional social work codes in the USA and Britain and the framework for social work training in Northern Ireland is noted. In this context the lack of any substantive inclusion of themes of religion and/or spirituality within the Bachelor of Social Work (BSW) degree at Queens University Belfast will be situated. A series of intersecting reasons for this lack of inclusion are proposed in terms of the experience of living through the recent troubled history of Northern Ireland and a variety of biases in academic thought.
A rationale for the re-introduction of inputs on religion and spirituality is articulated in terms of the widespread resurgence of these themes within health and social care and psychotherapy literature and the new emphasis on practicing in culturally sensitive ways in Britain. The first steps to re-introduce these themes under the higher context marker of “culturally competent practice” are described and an analysis of data from the students’ feedback presented along with illustrative quotations. The dissonance between the initial misgivings of staff and the overwhelmingly positive responses of students are highlighted. The chapter concludes with a discussion of lessons learned through the process with an emphasis on how the inclusion of these themes can result in better practice for service users, including those impacted by “the Troubles” in Northern Ireland.

Religion, Violence and Cities

In exploring the connections between religion, violence and cities, the book probes the extent to which religion moderates or exacerbates violence in an increasingly urbanised world. Originating in a five year research project , Conflict in Cities and the Contested State, concerned with Belfast, Jerusalem and other ethno-nationally divided cities, this volume widens the geographical focus to include diverse cities from the Balkans, the Middle East, Nigeria and Japan. In addressing the understudied triangular relationships between religion, violence and cities, contributors stress the multiple forms taken by religion and violence while challenging the compartmentalisation of two highly topical debates – links between religion and violence on the one hand, and the proliferation of violent urban conflicts on the other hand. Their research demonstrates why cities have become so important in conflicts driven by state-building, fundamentalism, religious nationalism, and ethno-religious division and illuminates the conditions under which urban environments can fuel violent conflicts while simultaneously providing opportunities for managing or transforming them.

Religion, Violence and Cities: An Introduction

The catalyst for this special issue was a symposium entitled Religion, Violence and Cities, held under the auspices of a five year inter-disciplinary research project on ethno-nationally divided cities.

While this project expressly addressed cities divided by ethno-national conflict, it was clear from the beginning that there was an important religious dimension to such conflicts in most, if not all, the cities being studied.2 The rationale of the Special Issue is to examine how this religious dimension exacerbates (or moderates) urban violence within a broad comparative context. Although three of the following articles are informed by Project research, we draw the net wider to encompass a broader geographical spread from the Balkans, the Middle East, Nigeria and Japan.

A new sensory organ in "primitive" molluscs (Polyplacophora Lepidopleurida), and its context in the nervous system of chitons

Introduction: Chitons (Polyplacophora) are molluscs considered to have a simple nervous system without cephalisation. The position of the class within Mollusca is the topic of extensive debate and neuroanatomical characters can provide new sources of phylogenetic data as well as insights into the fundamental biology of the organisms. We report a new discrete anterior sensory structure in chitons, occurring throughout Lepidopleurida, the order of living chitons that retains plesiomorphic characteristics.

Results: The novel "Schwabe organ" is clearly visible on living animals as a pair of streaks of brown or purplish pigment on the roof of the pallial cavity, lateral to or partly covered by the mouth lappets. We describe the histology and ultrastructure of the anterior nervous system, including the Schwabe organ, in two lepidopleuran chitons using light and electron microscopy. The oesophageal nerve ring is greatly enlarged and displays ganglionic structure, with the neuropil surrounded by neural somata. The Schwabe organ is innervated by the lateral nerve cord, and dense bundles of nerve fibres running through the Schwabe organ epithelium are frequently surrounded by the pigment granules which characterise the organ. Basal cells projecting to the epithelial surface and cells bearing a large number of ciliary structures may be indicative of sensory function. The Schwabe organ is present in all genera within Lepidopleurida (and absent throughout Chitonida) and represents a novel anatomical synapomorphy of the clade.

Conclusions: The Schwabe organ is a pigmented sensory organ, found on the ventral surface of deep-sea and shallow water chitons; although its anatomy is well understood, its function remains unknown. The anterior commissure of the chiton oesophagial nerve ring can be considered a brain. Our thorough review of the chiton central nervous system, and particularly the sensory organs of the pallial cavity, provides a context to interpret neuroanatomical homology and assess this new sense organ.

Religion, anti-slavery, and identity: Irish Presbyterians, the United States, and transatlantic evangelicalism, c. 1820-1914

Scholars have devoted much attention to the causes and consequences of Presbyterian emigration from Ulster to the thirteen colonies before 1776. This article moves beyond the eighteenth century to examine the continued religious links between Presbyterians in Ireland and the United States in the nineteenth century. It begins with an examination of the influence of evangelicalism on both sides of the Atlantic and how this promoted unity in denominational identity, missionary activity to convert Catholics, and revivalist religion during the first half of the century. Though Irish Presbyterians had great affection for their American co-religionists, they were not uncritical, and significant tensions did develop over slavery. The article then examines the religious character of Scotch-Irish or Ulster-Scots identity in the late nineteenth century, which was articulated in response to the alleged demoralising influence of large-scale Irish immigration during and after the Famine of the 1840s, the so-called Romanisation of Catholicism, and the threat of Home Rule in Ireland. The importance of identity politics should not obscure religious developments, and the article ends with a consideration of the origins and character of fundamentalism, perhaps one of the most important cultural connections between Protestants in Northern Ireland and the United States in the twentieth century.