Minor- and trace-element composition of trioctahedral micas: a review

Abstract

More than 19,000 analytical data mainly from the literature were used to study statistically the distribution patterns of F and the oxides of minor and trace elements (Ti, Sn, Sc, V, Cr, Ga, Mn, Co, Ni, Zn, Sr, Ba, Rb, Cs) in trioctahedral micas of the system phlogopite-annite/siderophyllite-polylithionite (PASP), which is divided here into seven varieties, whose compositional ranges are defined by the parametermgli(= octahedral Mg minus Li). Plots of trace-element contentsvs.mglireveal that the elements form distinct groups according to the configuration of their distribution patterns. Substitution of most of these elements was established as a function ofmgli. Micas incorporate the elements in different abundances of up to four orders of magnitude between the concentration highs and lows in micas of ‘normal’ composition. Only Zn, Sr and Sc are poorly correlated tomgli. In compositional extremes, some elements (Zn, Mn, Ba, Sr, Cs, Rb) may be enriched by up to 2–3 orders of magnitude relative to their mean abundance in the respective mica variety. Mica/melt partition coefficients calculated for Variscan granites of the German Erzgebirge demonstrate that trace-element partitioning is strongly dependent on the position of the mica in the PASP system, which has to be considered in petrogenetic modelling.This review indicates that for a number of trace elements, the concentration ranges are poorly known for some of the mica varieties, as they are for particular host rocks (i.e. igneous rocks of A-type affiliation). The study should help to develop optimal analytical strategies and to provide a tool to distinguish between micas of ‘normal’ and ‘abnormal’ trace-element composition.

Petrogenesis of rare-metal pegmatites in high-grade metamorphic terranes: a case study from the Lewisian Gneiss Complex of north-west Scotland

“…The trace element composition of muscovite mica has been reported to be another useful indicator of the extent of fractionation in rare-metal pegmatites (Tischendorf et al, 2001;London, 2008). In highly fractionated pegmatites the concentrations of Rb, Cs, Li, Mn, Ga, Tl, Sn and Ta in muscovite mica increase, whilst (Dickinson, 1974;Witty, 1975;Horsley, 1978;Baba, 2003;Hollis et al, 2006).…”

Zn and Pb mobility during metamorphism of sedimentary rocks and potential implications for some base metal deposits

“…The Zn content of the micas is independent of their major element composition (ESM Fig. A4), as was also shown by Tischendorf et al (2001). This is important as micas are the most important Fe and Mg host in our samples; hence, Zn variability of the bulk rock reflects protolith variations and is not related to partitioning preferences of micas with different chemical compositions.…”

Primary Sn-rich titianite in the Qitianling granite, Hunan Province, southern China: An important type of tin-bearing mineral and its implications for tin exploration

“…In highly peraluminous granites, cassiterite is the most common accessory mineral of magmatic origin [1,3,26] . Additionally, mica is commonly treated as a kind of Sn-bearing mineral in the granites [5,27,28] . In contrast, titanite is a type of accessory mineral commonly present in granites, especially in calc-alkaline granites.…”

“…The hydrothermal alteration of the primary titanite and subsequent crystallization of cassiterite recorded a process of leaching and accumulation of tin in magmatic-hydrothermal evolution of the Sn-bearing granite. Thus, this titanite has important implications for tin exploration.Sn-bearing titanite, genetic mineralogy, implications for tin exploration, Qitianling, granite Tin deposits are genetically related to granitic rocks; thus, numerous studies have devoted to establishment of mineralogical, petrological, and geochemical criteria for tin-bearing granite [1][2][3][4][5] . In the literature, mica (mainly biotite) is generally treated as a type of diagnostic Sn-bearing mineral in granites.…”

“…Tin deposits are genetically related to granitic rocks; thus, numerous studies have devoted to establishment of mineralogical, petrological, and geochemical criteria for tin-bearing granite [1][2][3][4][5] . In the literature, mica (mainly biotite) is generally treated as a type of diagnostic Sn-bearing mineral in granites.…”