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

ATAHUALPA VALENÇA PADILHA, JAIR CARVALHO DA SILVA JR, SEBASTIÃO DOMINGOS DE OLIVEIRA

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).

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