The Sveconorwegian Pegmatite Province – Thousands of Pegmatites Without Parental Granites

Tools and Workflows for Grassroots Li–Cs–Ta (LCT) Pegmatite Exploration

“…However, pegmatites with a missing apparent parental granite are common [3], and it is suspected that the source granite occurs at depth [30]. On the other hand, studies published in the 2010s on the anatectic origin of granitic pegmatites in Europe and North America demonstrate that there are "thousands of pegmatites without parental granites" [13], i.e., pegmatite fields can be unrelated to a source granite and instead form by partial melting and anatexis of crustal material [4,13,14,[35][36][37][38][39], or energy and melt circulation along deep lithospheric fault zones [40]. In the current literature, there are numerous descriptions of pegmatite sub-classifications, but to date there is no universally accepted model explaining the diverse features and genesis of granitic pegmatites [39].…”

“…For example, Dill (2015) [10] describes the spatial association of Variscan NYF and LCT pegmatites at Pleystein and Hagendorf (Germany), respectively, which would imply two drastically different geodynamic settings across a distance of several kilometres. Studies of pegmatite occurrences in the Sveconorwegian orogen have shown that NYF pegmatites do not only form in anorogenic (A-type magmatism) settings, but also in compressional or extensional orogenic settings unrelated to plutonic magmatism [13]. Additional shortcomings of theČerný and Ercit classification [43] are the dependence on the crystallisation depth and pressure, which is commonly difficult to obtain, and a possible lack of characteristic REE and F-minerals in pegmatites, which do not allow to fit pegmatites into the NYF classification [41].…”

“…Additional shortcomings of theČerný and Ercit classification [43] are the dependence on the crystallisation depth and pressure, which is commonly difficult to obtain, and a possible lack of characteristic REE and F-minerals in pegmatites, which do not allow to fit pegmatites into the NYF classification [41]. Rare-element pegmatites that were formed in a pluton-unrelated setting can therefore lack the characteristic F ("NY" instead of "NYF") or Li ("CT" instead of "LCT") signature [13]. These aspects question the validity of the currently accepted classification.…”

“…which do not allow to fit pegmatites into the NYF classification [41]. Rare-element pegmatites that were formed in a pluton-unrelated setting can therefore lack the characteristic F ("NY" instead of "NYF") or Li ("CT" instead of "LCT") signature [13]. These aspects question the validity of the currently accepted classification.…”

“…Over the last four decades research into rare metal Li-Cs-Ta (LCT) pegmatite mineralisation has predominantly focused on the understanding of late-stage magmatic fractionation and hydrothermal alteration processes enriching incompatible elements of potential economic interest in felsic peraluminous melts. In particular, the mineralogy and geochemistry of LCT pegmatites have been studied in great detail and are presented in case studies from Canada and the US [1][2][3][4], Ireland [5,6], the European Variscides [7][8][9][10][11][12], the Sveconorwegian orogeny [13,14], Central-East Africa [15][16][17][18] and Australasia [19][20][21][22]. These case studies have resulted in the definition of tectonic, mineralogical and geochemical factors controlling the location of mineralisation and zonation within the roof of peraluminous S-type granite plutons, pegmatitic offshoots into metasedimentary country rock or anatectic melts with no established link to S-type granites.…”