The meta-igneous greenschists of the Start Complex, South Devon, are c
omposed of a mineralogically uniform, but texturally variable, actinol
ite-epidote-albite assemblage with retrogressed variants containing ch
lorite, muscovite, sphene, carbonate and oxidized opaque minerals. Geo
chemically they represent a suite of relatively primitive tholeiites,
exhibiting mild differentiation, depleted incompatible element abundan
ces, and variable light rare-earth-element-depletion patterns comparab
le to modem basalts from normal spreading ridge segments (N-MORB). As
the Start greenschists exhibit a number of chemical similarities to th
e nearby Upper Palaeozoic Lizard ophiolite, and MORB-type clasts withi
n the Rhenohercynian Zone generally, they may also represent local Var
iscan ocean crust, which floored small oceanic basins that separated t
he Old Red Sandstone continent from the Armorican microplate to the so
uth. The Start Complex could thus represent a previously unrecognized
oceanic component to the Variscan orogenic belt (Rhenohercynian Zone)
of Northwest Europe.