Diabase derived from a primitive mantle melt showing moderate enrichment of trace elements.
HerkunftA diabase from the Bull Run quarry near Centreville, Virginia
- LILE (Rb, Sr, K, Ba): 10.0-5000 µg/g.
- HFSE (Zr, Hf, Th, U, Nb, Ta) 0.3-100 µg/g.
- Transition metals (Sc, V, Cr, Co, Ni, Cu, Zn, Mo) 0.5-270 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).