Tectonic evolution of the southern part of Aravalli Mountain Belt and its environs: Possible causes and time constraints

Structural studies on Proterozoic rocks belonging to the Lunavada Group, So uthern Aravalli Mountain Belt (SAMB), India, have shown that they underwent three episodes of deformation which have led to the formation of various r egional scale interference patterns. Whilst the northern parts of the SAME underwent brittle-ductile deformation, the southern portion underwent more ductile deformation. On the basis of structural as well as metamorphic stud ies it has been established earlier that the region was subjected to uplift orogenesis during its evolutionary history. In the present paper an attemp t is made to visualize the possible causes that led to deformation of the S AME, the structural geology of which has been established by the authors, a nd to constraint the timing of these events on the basis of already availab le geochronological data. A "working-hypothesis" is proposed according to w hich it is suggested that deformation of the SAME is a result of the accret ion of the three protocontinents viz. Aravalli, Dharwar and Singhbhum durin g the Mesoproterozoic. It is envisaged that the accretion of Aravalli and S inghbhum Protocontinents occurred between 160 and 1400 Ma along the NE-SW t rending Son Suture and this event led to development of NE-SW trending stru ctures in the SAME. Suturing of Aravalli and Dharwar Protocontinents betwee n 1400 and 935 Ma along the E-W Narmada Suture was responsible for the E-W to NW-SE trending D-3 structures of the SAME. It is postulated that the Sat pura orogeny which resulted in deformation of rocks in Satpura mountain ran ge lying to the south of Narmada Suture was coeval with the accretion of Ar avalli and Dharwar Protocontinents.