A UNIDADE METAVULCÂNICA DO GRUPO NOVA LIMA NO CÓRREGO DOS BOIADEIROS: UMA SEQUÊNCIA ULTRA MÁFICA-MÁFICA KOMATIÍTICA NA BASE DO SUPERGRUPO RIO DAS VELHAS, NA ÁREA CENTRAL DO QUADRILÁTERO FERRÍFERO - MINAS GERAIS

Resumo

The Rio das Velhas Supergroup has been subdivided by Ladeira (1980) into three unamed units, comprising a basal metavolcanic sucession followed by chemical sediments overlain by a clastic unit. The lithologies described in this work belong to the mentioned metavolcanic unit, although they can be spatia1ly, geochemically and pretrologically described as follows: serpentínized ultramafic rocks (meta-komatiites), actinolite-tremolite schísts, chloríte schísts (meta-basalts). Geochemically these metavolcanics represent a komatiitic sequence exhibiting relict structures and textures (e.g. spinifex and cumulate textures and columnar jointing).