Chemistry of kimberlite indicator minerals and sphalerite derived from glacial sediments of northwest Alberta

This paper provides a summary of traditional, current, and developing exploration techniques using indicator minerals derived from glacial sediments, with a focus on Canadian case studies. The 0.25 to 2.0 mm fraction of heavy mineral concentrates (HMC) from surficial sediments is typically used for indicator mineral surveys, with the finer (0.25–0.50 mm) fraction used as the default grain size for heavy mineral concentrate studies due to the ease of concentration and separation and subsequent mineralogical identification. Similarly, commonly used indicator minerals (e.g., Kimberlite Indicator Minerals—KIMs) are well known because of ease of optical identification and their ability to survive glacial transport. Herein, we review the last 15 years of the rapidly growing application of Automated Mineralogy (e.g., MLA, QEMSCAN, TIMA, etc) to indicator mineral studies of several ore deposit types, including Ni-Cu-PGE, Volcanogenic Massive Sulfides, and a variety of porphyry systems and glacial sediments down ice of these deposits. These studies have expanded the indicator mineral species that can be applied to mineral exploration and decreased the size of the grains examined down to ~10 microns. Chemical and isotopic fertility indexes developed for bedrock can now be applied to indicator mineral grains in glacial sediments and these methods will influence the next generation of indicator mineral studies.

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Ultrabasic eruptives with alnöitic-kimberlitic affinities from Malaita, Solomon Islands

Mineralogical Magazine and Journal of the Mineralogical Society ◽

10.1180/minmag.1965.034.268.02 ◽

1965 ◽

Vol 34 (268) ◽

pp. 16-34 ◽

Cited By ~ 26

Author(s):

J. B. Allen ◽

T. Deans

Keyword(s):

Solomon Islands ◽

Chemical Analyses ◽

Alkaline Rocks ◽

Kimberlite Indicator Minerals ◽

Host Rocks ◽

Indicator Minerals

SummaryA detrital assemblage of magnesian ilmenite, pyrope, chrome-diopside, rutile, and zircon has been traced to outcropping ultrabasic alkaline rocks, hitherto unknown in the Melanesian region. Analyses and descriptions of these ‘kimberlite indicator minerals’ are given. The host rocks comprise alnöite, an alnöite breccia with calcite matrix, and a magnesian ankaratrite, which are described, with chemical analyses. Emphasis is laid on the abundance of ultrabasic inclusions and xenocrysts and the replacements and transformations they have undergone. Malaita Island promises to contribute significantly to the understanding of the relations between alnöite, melilite basalts, and kimberlites.

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Assessment of the Amaruq gold deposit signature in glacial sediments using multivariate geochemical data analysis and indicator minerals

Journal of Geochemical Exploration ◽

10.1016/j.gexplo.2021.106800 ◽

2021 ◽

pp. 106800

Author(s):

Victor de Bronac de Vazelhes ◽

G. Beaudoin ◽

I. McMartin ◽

O. Côté-Mantha ◽

N. Boulianne-Verschelden

Keyword(s):

Data Analysis ◽

Gold Deposit ◽

Geochemical Data ◽

Glacial Sediments ◽

Indicator Minerals ◽

Geochemical Data Analysis

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The Tikiusaaq carbonatite: a new Mesozoic intrusive complex in southern West Greenland

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/geusb.v10.4905 ◽

2006 ◽

Vol 10 ◽

pp. 41-44 ◽

Cited By ~ 6

Author(s):

Agnete Steenfelt ◽

Julie A. Hollis ◽

Karsten Secher

Keyword(s):

Lithospheric Mantle ◽

Chemical Elements ◽

Country Rock ◽

Alkaline Rock ◽

Geological Mapping ◽

Carbonatite Complex ◽

West Greenland ◽

Alkaline Rocks ◽

Kimberlite Indicator Minerals ◽

Indicator Minerals

Ultrabasic alkaline magmatic rocks are products of melts generated deep within or at the base of the lithospheric mantle. The magmas may reach the surface to form lavas and pyroclastic deposits; alternatively they crystallise at depth to form dykes or central complexes. The rocks are chemically distinct and may contain high concentrations of economically interesting minerals and chemical elements, such as diamonds, niobium, tantalum, rare earth elements, phosphorus, iron, uranium, thorium, and zirconium. Ultrabasic alkaline rocks are known from several provinces in Greenland, but extrusive facies have only been preserved at a few places; e.g. at Qassiarsuk in South Greenland where pyroclastic rocks occur, and in the Maniitsoq region, where a small volcanic breccia (‘Fossilik’) contains fragments of Palaeozoic limestone. Ultramafic lamprophyre and kimberlite are mainly emplaced as dykes, whereas carbonatite forms large intrusive bodies as well as dykes. The ultrabasic alkaline magmas that have been emplaced at certain times during the geological evolution of Greenland can be related to major episodes of continental break-up (Larsen & Rex 1992). The oldest are Archaean and the youngest dated so far are Palaeogene. Figure 1 shows the distribution of known ultrabasic alkaline rocks in West Greenland. The large and well-exposed bodies of alkaline rocks and carbonatites in the Gardar Province were discovered already in the early 1800s (Ussing 1912), while less conspicuous bodies were discovered much later during geological mapping and mineral exploration. Many alkaline rock bodies, particularly dykes, are difficult to identify in the field because they weather more extensively than the country rock gneisses and form vegetated depressions in the landscape. However, their distinct chemistry and mineralogy render alkaline rocks identifiable in geochemical and geophysical survey data. Thus, the Sarfartôq carbonatite complex was discovered during regional airborne gamma-spectrometric surveying owing to its elevated uranium and thorium contents (Secher 1986). The use of kimberlite indicator minerals has led to the discovery of alkaline rocks such as kimberlites and ultramafic lamprophyres that carry fragments of deep lithospheric mantle. Such rocks may also contain diamonds. Kimberlite indicator minerals are high-pressure varieties of minerals, such as garnet, clinopyroxene, chromite and ilmenite that were formed in the lithospheric mantle. Exploration companies have processed thousands of till samples from southern West Greenland for kimberlite indicator minerals and found many new dykes.

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