Komatiite Barberton South Africa - Oldest Lavas on Earth

The Barberton Greenstone Belt, located on the eastern edge of the Kaapvaal Craton in South Africa, is renowned for its geological significance and rich mineralization. Within this ancient belt lies a remarkable rock type known as komatiite. Let’s delve into the fascinating details:

Key Points:

1. Komatiite Definition:

   • Komatiite is an unusual ultramafic volcanic rock named after the Komati River, which flows through the Barberton Greenstone Belt.
   • It crystallized from lava with at least 18% magnesium oxide (MgO), producing high magnesium content.
   • These rocks are among the oldest exposed on Earth, dating back to more than 3.6 billion years.

2. Formation and Composition:

   • The Barberton Greenstone Belt hosts a sequence of mafic to ultramafic lavas and metasedimentary rocks.
   • Komatiites formed between 3.5 and 3.2 billion years ago.
   • Two significant rock suites are present:
     • Tonalite-trondhjemite-granodiorite (TTG) suite (emplaced around 3.5–3.2 Ga).
     • Granite-monzogranite-syenite (GMS) suite (emplaced around 3.2–3.1 Ga).
   • The GMS suite, found across the Kaapvaal Craton, coincides with the craton’s first stabilization.

3. Geological Significance:

   • The Barberton Greenstone Belt provides a window into early Earth processes.
   • It contains some of the oldest traces of life, second only to the Isua Greenstone Belt in Western Greenland.
   • The Makhonjwa Mountains constitute 40% of the Barberton belt.

4. Komatiite and Spinifex Texture:

   • Komatiites exhibit a unique  “spinifex texture” characterized by large dendritic plates of olivine and pyroxene.
   • Their extreme fluidity during eruption led to thin lava flows, which resemble large, outstretched tree roots when cooled. This is in part why they have this strange crust.

Size: 26mm X 20mm X 13mm, Weight: 7.6 grams

Ships with a Certificate of Authenticity and tag. Photo cube not included.

Here is a rare opportunity to add the oldest lava on Earth to your geological collection.