Alkaline ultramafic lamprophyres and associated carbonatite dykes from the Kalix area, northern Sweden

Abstract

ZusammenfassungAlkalin-ultrabasische Lamprophyre und begleitende Karbonatitg~inge bilden nordsiidlieh streidmnde Gangsdaw~irme. Die Lamprophyre zeigen gewisse ~hnlichkeiten zu alnSitischen und kimberlitischen Gesteinen; sie wurden unterteilt in glimmerreiche und pikritische Lamprophyre sowie Brekzien. Karbonatite im engeren Sinn treten nur sehr untergeordnet auf; sie sind als Beforsite charakterisiert.Die Ganggesteine des Kalix-Gebiets weisen groBe ~hnlichkeiten mit petrographisch verwandten Gesteinen von anderen skandinavischen Vorkommen (Sokli, AIn5 und Fen) auf. Grundsiitzliche Untersehiede finden sich vor allem im tektonischen Auftreten (ziemlich konstant streichende Gangsehw~irme) und im Verteilungsmuster der seltenen Erden (deutlida negative Cer-Anomalien).Die Bfldung der Kalix-G/inge wird folgenderweise erkl~irt: (1) Partielle Aufschmelzung des oberen Mantels, (2) Intrusion der Sehmelze in eine krustale Magmakammer, gefolgt yon fraktionierter Kristallisation, (3) Beaktion zwischen vorzugsweise kristallisiertem Material und der volatilen Phase (Entarmung an leichten seltenen Erden, Oxidation des Cers), (4) Intrusion in Bruehzonen, die horizonteller Dehnung ansgesetzt sind. AbstractAlkaline ultramafic lamprophyres and associated carbonatite dykes form north-south trending dyke swarms. The lamprophyres are sub-divided into micaceous, picritic and breccia varieties. Carbonatites sensu stricto (beforsites) occur very subordinate.The dykes of the Kalix area show great similarities to petrographically related rocks from other Scandinavian occurrences (Sokli, Aln6 and Fen). Major differences are found in their tectonic setting (regularly striking dyke swarms) and the REE-pattern (distinctly negative cerium anomalies).The following petrogenetic model is advanced for the Kalix dykes: (1) partial melting of upper mantle material, (2) Intrusion into a crustal magma chamber, fractional crystallization, (8) Interactions between crystallized material and the volatile phase 0ight REE depletion, oxidation of cerium), (4) Intrusion in fracture zones under horizontal tension.

Europe's rare earth element resource potential: An overview of REE metallogenetic provinces and their geodynamic setting

“…Strange Lake, Miller et al (1997)) and possibly into Sweden (e.g. the Kalix-Storö dykes, Kresten et al (1981)), thus indicating a wide network of rift zones and alkaline magmatism associated with the break-up of Columbia. To date, the Gardar Province is considered to represent the most important area of REE resources in Europe.…”

Geochemistry of Rare Earth Elements in Bedrock and Till, Applied in the Context of Mineral Potential in Sweden

“…Chemically, potassic lamprophyre dikes are often characterized by relatively low SiO 2 and TiO 2, and high MgO and K 2 O contents. In addition, they show high content of large-ion lithophile trace elements (e.g., Rb, Sr, and Ba) and LREE, but low content of high-field-strength elements (e.g., Nb, Ta, Zr, Hf, and Ti) [20]. An example of the REE-enriched lamprophyre is the 1.1 Ga alkaline ultramafic dykes up to 1-metre-wide, outcropping along the northernmost part of the coast in the Gulf of Bothnia, (Kalix) known as Storön deposit (Figure 1; [20,21]).…”

“…An example of the REE-enriched lamprophyre is the 1.1 Ga alkaline ultramafic dykes up to 1-metre-wide, outcropping along the northernmost part of the coast in the Gulf of Bothnia, (Kalix) known as Storön deposit (Figure 1; [20,21]). The dikes represent olivine-and mica-rich lamprophyres and silico-carbonatites [21].…”