Typical mid-ocean-ridge basalt (MORB) depleted in most trace elements.
OriginAn olivine-bearing tholeiitic basalt collected from an interglacial lava flow near Reykjavik, the capital of Iceland
- LILE (Rb, Sr, K, Ba): 7.00-240 µg/g.
- HFSE (Zr, Hf, Th, U, Nb, Ta) 0.01-15 µg/g.
- Transition metals (Sc, V, Cr, Co, Ni, Cu, Zn, Mo) 0.07-400 µg/g.
Mafic rocks are characterised by a silica content of 45-52 m/m% and similar to ultramafic rocks also consist mainly of olivine and pyroxenes. They do however often also contain the calcium-rich varieties of feldspar and can contain iron-rich micas such as biotite. Basalts make up the oceanic crust, but can also be found on continents as so called Large Igneous Provinces (LIPs).