LETTER The masquerade of alkaline–carbonatitic tuffs by zeolites: a new global pathfinder hypothesis L. S. Campbell & A. Dyer & C. Williams & P. R. Lythgoe Received: 18 August 2011 /Accepted: 2 December 2011 /Published online: 21 December 2011 # Springer-Verlag 2011 Abstract Rapid and progressive reaction of alkaline–car- bonatitic tuffs with magmatic and crustal fluids disguises their initial character and origin. This is collectively indicat- ed from (a) the extensive literature on zeolite formation from volcanic glass precursors and alkaline fluids, (b) mineralog- ical characteristics of specific zeolite species, (c) a compar- ative review of global distributions of alkaline–carbonatite suites and of zeolite minerals, and (d) new trace element data from zeolite samples. A unifying conceptual model based on tectonic and geological settings, hydrological re- gime and mineralogy is presented that helps to explain the global distributions and current understanding of occurren- ces. The model will assist in resource exploration by contrib- uting deeper understanding of the economically important bedded zeolite deposits and further, serve as a guide to the discovery of new alkaline–carbonatitic suites, potentially of economic significance (metallic ores and rare earth elements). It follows that future testing of the hypothesis will impact on models of natural carbon cycling as volcanic contributions of CO 2 are reviewed. Keywords Natural zeolites . Alkaline magmatism . Carbonatites . Mineral reactivity . Trace elements Introduction In the last 50 years, the recognition of widespread occur- rences, both of primary carbonatites (igneous rocks com- posed largely of carbonate minerals, Tuttle and Gittins 1966; Bell 1989; Woolley and Kjarsgaard 2008a) and of natural zeolites (hydrated aluminium silicate minerals with open framework structures and important cation exchange properties, Mumpton 1981; Tschernich 1992), has been considerable. The successive growth of scientific understand- ing in these traditionally disparate fields has accelerated with multi-disciplinary advances in fundamental science, and also with the discovery and utilization of their respective natural resource potentials (Colella and Mumpton 2000; Bish and Ming 2001; Mitchell 2005; Wall and Zaitsev 2004; Woolley and Kjarsgaard 2008a, b). However, recognition of a global genetic link between these systems has, to date, not been conceptualized. The reasons are evident; with an emphasis on properties and applications of zeolite-group minerals, and on elucidating the highly complex composition–zonation pat- terns in zeolite occurrence studies, global patterns of funda- mental geological/tectonic setting are not readily apparent. Further, the complex, partially understood and controversial association between carbonatites and the huge diversity of alkaline rocks that exist would tend to make this highly specialized discipline less readily accessible to other scientists. In carbonatite science, the big questions are on magma origins Electronic supplementary material The online version of this article (doi:10.1007/s00126-011-0394-z) contains supplementary material, which is available to authorized users. L. S. Campbell (*) : P. R. Lythgoe School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK e-mail: Linda.Campbell@manchester.ac.uk A. Dyer Department of Chemistry, Loughborough University, Ashby Road, Loughborough, Leicestershire LE11 3TU, UK C. Williams School of Applied Science, University of Wolverhampton, Wulfruna Street, Wolverhampton WV1 1SB, UK Miner Deposita (2012) 47:371–382 DOI 10.1007/s00126-011-0394-z