The Petrology of a Teschenite Sill at Landywood, Staffordshire

Abstract

AbstractBorehole cores have been obtained of a basic igneous sill at Landywood, near Cannock, Staffordshire. This intrusion consists mainly of microteschenite with a zone of teschenite in the top half of the sill. Later parts of the parental magma of this intrusion were dryer and crystallized to give crinanite and analcite olivine dolerite. These later parts were not intruded in sufficient quantities to spread through the whole of the sill and were restricted to the vicinity of the feeding pipe. Extensive secondary replacement of plagioclase by chlorite and of pyroxene by carbonate occurs in the teschenitic parts of the sill and is ascribed to the action of water and carbon dioxide derived from the magma.