Field observations and pioneering high-temperature experiments undertaken a century ago by Norman L. Bowen founded the basis of modern igneous petrology. Bowen’s work concluded that the chemical differentiation of magmas was primarily controlled by the settling out of crystals from molten rock in magma chambers and the squeezing out of residual liquid. This crucial initial insight into the chemical and temporal evolution of magmatic systems informed and underpinned subsequent research on igneous differentiation: magma chambers behave as crystal-poor ‘boiling vats’ in the crust where crystals, bubbles and melt separate gravitationally, heat dissipated to their surroundings initiating crystallisation, driving igneous differentiation.
Since 1915, research advances in the physico-chemical properties of sub-volcanic magmatic systems coupled with rapid technological development have fundamentally revised our understanding of this simple model. Igneous petrologists now recognise this paradigm is rare with most natural magmatic systems primarily existing in partially molten (‘mushy’) states, as serially arranged and variably interconnected storage regions, periodically replenished by different fluxes of magma and heat. Complex interplay in these fluxes and variations in physico-chemical properties as they rise through and navigate the crustal system, provide the dominant controls on magmatic differentiation and the eventual igneous materials produced.
This volume presents the modern understanding of the chemical, physical and thermal evolution of crustal magmatic / volcanic systems derived from recent research advances in igneous/metamorphic petrology, geochemistry, geochronology and numerical / thermal modelling. Introduced with a contextual overview paper, the volume contains 10 recent contributions organised into four fully-indexed thematic sections: 1: magma fluxes and phase equilibria, 2: phase equilibria, physical properties of magma and melt extraction, 3: architecture of subvolcanic reservoirs and 4: volcanic conduits.
A thorough review of contemporary developments within this field, the anticipated readership is expected to be from postgraduate researchers and professional academic geoscientists specialising in igneous petrology and petrogenesis, geochemistry and allied disciplines. All contributions are well-written and edited, with clear and appropriate figures, photographs and data-tables, augmented with a spectacular cover photograph as a bonus!
In summary, the inherent complexities of the evolving perspective of magmatic systems reveal an account of ‘mushmatism’ more than magmatism. A fascinating and recommended read.
Reviewed by Mark Griffin
CHEMICAL, PHYSICAL AND TEMPORAL EVOLUTION OF MAGMATIC SYSTEMS by CARICCHI L and BLUNDY, J D (editors). Geological Society of London Special Publication No 422. 2015. Geological Society of London. ISBN 978-1-86239-732-3. Hbk. 223pp. ISSN 0305-8719. List Price: £100.00, www.geolsoc.org.uk.