This paper describes a new type of ultramafic flow at the basal portion of Crixás Greenstone Belt. It is characterised by randomly distributed orbicular structures of various dimensions. The structures show a carbonate nucleus and an external shell of talc, serpentine, and chlorite. Sometimes, centrally structured pseudomorphs of pyroxene and olivine are observed. The structures are thought to be originated from local turbulent flows provoked by lamellar flow of ultramafic lava according to the model of Alexander and Heinrich (1978) to orbicular lamprophyres of the alkaline mafic intrusion of Freemont County, Colorado. Occurrence of such structures in ultramafic lavas reinforces the possibility that liquid migration by lamellar flow, and consequent local turbulences along its trajectory, may originate orbicular structures, Besides, the presence of pseudomorphs found in the center of the orbicules suggests the previous existence of olivine crystals in suspension in the ultramafic magma.This paper describes a new type of ultramafic flow at the basal portion of Crixás Greenstone Belt. It is characterised by randomly distributed orbicular structures of various dimensions. The structures show a carbonate nucleus and an external shell of talc, serpentine, and chlorite. Sometimes, centrally structured pseudomorphs of pyroxene and olivine are observed. The structures are thought to be originated from local turbulent flows provoked by lamellar flow of ultramafic lava according to the model of Alexander and Heinrich (1978) to orbicular lamprophyres of the alkaline mafic intrusion of Freemont County, Colorado. Occurrence of such structures in ultramafic lavas reinforces the possibility that liquid migration by lamellar flow, and consequent local turbulences along its trajectory, may originate orbicular structures, Besides, the presence of pseudomorphs found in the center of the orbicules suggests the previous existence of olivine crystals in suspension in the ultramafic magma.