Orgin and Palaeoenvironmental Aspects of Red Sediments from Bavanapadu-Ichchapuram, Andhra Pradesh

Red sediments occur as three shore linear patches between Bavanapadi and Ichchapuram in north Andhra Pradesh coast. The unstructured red sediment lying over an antecedent topography is divisible into lower unit with calcretes and upper unit devoid of calcretes. The field observations, grain size parameters, heavy mineral assemblage and SEM studies of quartz grains signify an aeolian source, possibly formed by sand transport from the exposed continental shelf during the Quaternary regressive cycles. Formation of calcrete and red pigments are considered as post depositional phenomena. SEM studies of ilmenite, XRD and chemical studies of finer fractions reveal the in situ derivation of red haematite and goethite pigments from the alteration of ilmenite and precipitated interstitially to give rise to red colour.