Joint Patterns and their Significance to the Tectonic History

On the basis of the relative intensity of the tectonic disturbances in the Medivada-Vaddadi area in Visakhapatnam district of Andhra Pradesh, the area is subdivided into two domains, homogeneous and inhomogeneous, for the purpose of the study of joints, The subdivision of this contiguous area into two distinct domains is corroborated by applying the Snedecors F-test for the equality of variances for the variables - strike and dip of the joints and the test for the equality of covariances for the variates - strike and dip taken together.

Only in the inhomogeneous domain there is superposition of the low-angled joint pattern on the pre-existing joint pattern consisting of three sets of joints - J₁, J₂, J₃.

The first order joints J₁, J₂ and J₃ might have probably formed during the folding of the beds, and the second order joints with low dips were formed during the readjustment of stress after the folding, jointing and faulting.

The application of the results of the study of the joints to the mineralised zones in areas of superimposed tectonic deformation is indicated.