Aillikite

Aillikite: An ultramafic carbonate-rich lamprophyre consisting of various phenocrysts including olivine, diopsidic pyroxene, amphiboles and phlogopite in a matrix of similar minerals with at least partly primary carbonate and minor perovskite but no melilite. (Le Maitre, 2005)

The International Union of Geological Sciences (IUGS) has played an important role in establishing a systematic classification scheme for igneous rocks and simplifying their nomenclature. The main principle in their hierarchical approach is to deal with exotic or special rocks first, thus clearing the way for the classification of the normal, or majority of, igneous rocks. Included amongst the special rocks are pyroclastics, carbonatites, kimberlites, lamproites and lamprophyres.
Unfortunately, a widely recognized group of exotic alkaline rocks, the ultramafic lamprophyres (UML; Rock, 1986, 1991), were never integrated into IUGS classification schemes. Some of the group members (e.g. alnoite and polzenite) were considered within early versions of the IUGS system , whereas others were ignored from the beginning (aillikite and damtjernite). In the most recent IUGS classification scheme (Le Maitre, 2002) all ultramafic lamprophyre group members have been entirely omitted.

Tappe., et al. (2005) have introduced a simplified version of Rock’s (1986) classification of ultramafic lamprophyres:

Alnoites: are melilite-bearing UML, characterized by olivine, phlogopite and clinopyroxene macrocrysts and/ or phenocrysts, and groundmass melilite, clinopyroxene, phlogopite, spinel, ilmenite, perovskite, Ti-rich garnet, apatite and minor primary carbonate. Monticellite may occur in rare instances.

Aillikites: are carbonate-rich UML, characterized by olivine and phlogopite macrocrysts and/or phenocrysts, and groundmass primary carbonate, phlogopite, spinel, ilmenite, rutile, perovskite, Ti-rich garnet and apatite. Mela-aillikites are more melanocratic (colour index >90%) as a result of the presence of clinopyroxene and/or richteritic amphibole in the groundmass (at the expense of carbonate). Monticellite may occur in rare instances.

Damtjernites: are feldspathoid- and/or alkali feldsparbearing UML, characterized by olivine, phlogopite and clinopyroxene macrocrysts and/or phenocrysts, and groundmass phlogopite/biotite, clinopyroxene, spinel, ilmenite, rutile, perovskite, Ti-rich garnet, titanite, apatite and primary carbonate, with essential minor nepheline and/or alkali feldspar.


uml.jpg

Classification of ultramafic lamprophyres based on their diagnostic mineralogy. Modified by Tappe., et al. (2005).




The ultramafic lamprophyres (UML) are a widely recognized group of alkaline igneous rocks associated with continental extension; however, their origin is poorly understood. Although they are volumetrically minor components of continental magmatism, they are of fundamental significance for our understanding of deep melting events during the initial stages in the development of continental rifts. UML typically occur as dyke swarms, but their genesis has commonly been discussed as though they are varieties of kimberlite. However, compositional differences and the lack of spatial coexistence between contemporaneous UML and suggest that they are derived from distinct magma types.

The occurrence of UML is largely confined to regions of lithospheric extension and they are commonly associated with carbonatite magmatism. Additionally, UML magmatism forms the earliest igneous activity in some flood basalt and also occurs on oceanic plateaux. In contrast, kimberlites occur exclusively within areas of stable Archean cratons or in the surrounding Proterozoic mobile belt. As for kimberlites, UML magmas may contain diamonds, indicating that the depth of melting can be in excess of 150 km (>5 GPa).


aillikite.jpg

Aillikite dyke. Cape Aillik, Labrador, Canada.



alnoite2016.jpg

Alnoite with mafic macrocrysts. Oka alkaline complex, Quebec, Canada.



Damtjernite.jpg

Damtjernite with mafic macrocrysts. Fen complex, Norway.




Sample doned by Anton Chakhmouradian (University of Manitoba)

allikite(andy)(1).jpg

Panoramic view of the aillikite thin section. Image by Andy Tindle (Virtual Microscope). PPL image, field of view = 2.5cm.




allikite(andy)(2).jpg

Panoramic view of the aillikite thin section. Image by Andy Tindle (Virtual Microscope). XPL image, field of view = 2.5cm.



Bibliography



• Tappe, S., Foley, S. F., Jenner, G. A., & Kjarsgaard, B. A. (2005). Integrating ultramafic lamprophyres into the IUGS classification of igneous rocks: rationale and implications. Journal of Petrology, 46(9), 1893-1900.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., & Bateman, P. (Eds.). (2005). Igneous rocks: a classification and glossary of terms: recommendations of the International Union of Geological Sciences Subcommission on the Systematics of Igneous Rocks. Cambridge University Press.
• Tappe, S., Foley, S. F., Jenner, G. A., Heaman, L. M., Kjarsgaard, B. A., Romer, R. L., & Hoefs, J. (2006). Genesis of ultramafic lamprophyres and carbonatites at Aillik Bay, Labrador: a consequence of incipient lithospheric thinning beneath the North Atlantic craton. Journal of Petrology, 47(7), 1261-1315.

Photo
aillikite(1).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(2).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(3).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(4).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(5).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(6).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(7).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(8).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(9).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(7).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(8).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(9).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(10).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(11).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(12).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(13).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(14).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(15).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(16).jpg

Amphiboles, apatite (colorless) and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(17).jpg

Amphiboles, apatite (I order gray) and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 1x (Field of view = 9mm)
aillikite(18).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 1x (Field of view = 9mm)
aillikite(20).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(21).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(22).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(23).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(24).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(25).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(26).jpg

Amphibole crystal within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(27).jpg

Amphibole crystal within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(28).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(29).jpg

Amphiboles, apatite (colorless) and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(30).jpg

Amphiboles, apatite (I order gray) and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(31).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(32).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(33).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(34).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(35).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(36).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(37).jpg

Amphibole crystal within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(38).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(39).jpg

Amphiboles, apatite (colorless) and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(40).jpg

Amphiboles, apatite (I order gray) and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(41).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(42).jpg

Amphiboles and phlogopite crystals within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(44).jpg

Amphibole crystal within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(47).jpg

Amphibole crystal within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. PPL image, 2x (Field of view = 7mm)
aillikite(48).jpg

Amphibole crystal within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)
aillikite(49).jpg

Amphibole crystal within a primary carbonate-rich groundmass. Aillikite from Aley British Columbia, Canada. XPL image, 2x (Field of view = 7mm)