Komatiite Protolith Færingehavn Greenland [96 g ~ 3.8 Ga]
Brand : Jensan Scientifics LLC
- SKU:
- JPT-35948
- Condition:
- New
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- Weight:
- 1.00 LBS
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Komatiitic ultramafic rock from Færingehavn, Greenland
This specimen is a metasomatized ultramafic rock whose protolith was komatiitic lava erupted 3.8 billion years ago during the Eoarchean. It came from Innersuartuut, an island in the Ameralik area of southern West Greenland, where Akilia-association enclaves sit locked inside the Itsaq Gneiss Complex. Burial, shearing, and recrystallization destroyed the lava. The chemistry survived, and the chemistry is why geochemists keep returning to this outcrop.
What is Komatiite Protolith?
The description tag describes it accurately as metasomatized komatiitic ultramafic rock, ca. 3.8 Ga, Ameralik locality, Færingehavn terrane, Itsaq Gneiss Complex, southern West Greenland. Every word in it is load-bearing.
Komatiitic describes the parent melt. Komatiite is an ultramafic volcanic rock that requires an extraordinarily hot mantle to form — hot enough that the Earth has not produced any since the Archean. Metasomatized describes what happened afterward: amphibolite- to granulite-facies metamorphism during terrane amalgamation stripped away spinifex texture, glassy chill margins, and flow tops, and rebuilt the rock as a metamorphic assemblage of anthophyllite, tremolite, talc, chlorite, and metamorphic olivine and pyroxene.
The correct term is komatiite protolith. Protolith names the parent, and the parent was komatiite. Metamorphism erased everything else about the original lava, and geochemists read the Eoarchean mantle from the remaining geochemistry.
The Late Veneer — The Real Headline
Highly siderophile elements (HSEs — osmium, iridium, ruthenium, rhodium, platinum, palladium) are iron-loving. During Earth's core formation, they should have been almost entirely scavenged into the core. The mantle contains them anyway. The standard explanation is a late veneer: a chondritic dusting of material delivered after the core had finished forming.
That model makes a testable prediction. If the veneer needed time to stir into the mantle, then the oldest mantle-derived rocks should be poor in HSEs relative to modern ones, not rich in them.
Scientists identified some of the most depleted HSE abundances on record for this rock type — platinum averaging 2.3 ppb in the Innersuartuut ultramafics. Scientists believe that the West Greenland Akilia association is the best surviving record of pre-late-veneer mantle HSE abundances.
How Rare is Eoarchean Crust?
Nutman and Friend put all surviving crust older than 3600 million years, worldwide, at one-millionth of the modern crust. Ultramafic volcanic rock from that window is rarer still. Two places on Earth produce it: the Akilia association of West Greenland and the Inukjuak domain of northern Québec. That is the total global inventory!
This piece comes from the 0.0001% of Earth's earliest crust that survived.
Product Information
| Specimen | Metasomatized komatiitic ultramafic rock (komatiite protolith) |
| Protolith Age | ca. 3.8 Ga — Eoarchean |
| Locality | Innersuartuut, Ameralik, Færingehavn Terrane, Itsaq Gneiss Complex, southern West Greenland |
| Geologic Setting | Akilia-association supracrustal enclave within the Itsaq Gneiss Complex, North Atlantic Craton |
| Weight | 96 grams |
| Dimensions | 73 mm L × 65 mm W × 8 mm D |
| Preparation | Hand-finished, cut flat, front and back. No repairs, no coatings, no sprayed water. |
| Collection | Legally collected. In situ field photograph included. |
| What's Included | Certificate of Authenticity, detailed specimen information, tag, and tag stand |
| SKU | JPT-35948 |
Images professionally photographed under controlled studio lighting using Zeiss optics and a pro-grade Canon camera, for guaranteed accuracy.
Rarity and Significance
| Geologic Age | ★★★★★ Among the oldest rock available |
| Rarity of Material | ★★★★★ Eoarchean ultramafic volcanic rock from two localities worldwide |
| Scientific Importance | ★★★★★ Central to the late-veneer and early mantle-temperature |
| Educational Value | ★★★★★ Teaches about the Late Veneer, Archean rocks, ultramafic rocks, and Earth's oldest rock localities |
Questions Commonly Asked
Is this a komatiite or not?
It is a komatiite protolith. The original rock was komatiitic lava; subsequent metamorphism recrystallized it into an ultramafic rock. Scientists have identified the Innersuartuut rocks as komatiitic in origin.
Is it the oldest komatiite on Earth?
It sits among the oldest known komatiitic rocks. The settled figures are a ~3.8 Ga protolith age and an Eoarchean setting.
What does depletion in osmium and iridium tell us?
Depletion is what the late-veneer model predicts. If the chondritic veneer arrived after core formation and took time to mix through the mantle, the oldest mantle-derived rocks should be the poorest in these elements. Innersuartuut material ranks among the most HSE-depleted material measured for its rock type.
How is the ~3.8 Ga age established?
Published geochronology on the Akilia-association enclaves within the Itsaq Gneiss Complex clusters at 3.77–3.83 Ga, corroborated by cross-cutting relationships with the surrounding gneisses.
What is included with this specimen?
A Certificate of Authenticity, detailed information on komatiite and the Færingehavn Terrane, and a specimen tag carrying the full locality ladder together with its own display stand.
Who is this specimen for?
Collectors building a deep-time or Earth's-oldest-rocks suite, university and museum teaching collections, and anyone who wants a physical anchor for the early Earth chapter of a geology course. It pairs with Isua pillow lava for a Greenland Eoarchean set, or with Barberton komatiite for a comparison spanning 3.8 Ga Greenland to 3.5 Ga South Africa — two cratons, two windows into the early Archean.
A 96-gram piece of metasomatized komatiitic ultramafic rock from Innersuartuut, in the Færingehavn Terrane of southern West Greenland, with a protolith age of 3.8 billion years. Its parent was komatiitic lava erupted onto an Earth whose mantle ran hundreds of degrees hotter than today's, and the chemistry it still carries places it at the center of the late veneer. It is cut flat on both sides and came from the small fraction of Earth's earliest crust that survives anywhere on the planet.
