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Sankara Pitchaiah, P.
- Origin of White Sands from Prakasam District, Andhra Pradesh
Authors
1 Department of Geology, Andhra University, Waltair, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 26, No 4 (1985), Pagination: 275-280Abstract
White sands in Prakasam District, Andhra Pradesh, occur as a narrow zone extending 45 km in length and 3-4 km in width between Karlapalem and Chinnaganjam. The origin and provenance of white sands are worked out based on geology and textural analysis of the white sand belt. The textural parameters and the gradational changes in the white sands support interpretation of the depositional environment as belonging to a beach system. The sub-angular to sub-rounded shape of the grains and appreciable amount of feldspars in the white sands suggest that they have undergone transportation locally and originated from a nearby source. It is established that the Gondwana sandstones exposed around Pavalur and Budavada were the source rocks for the white sands and they were deposited as a near shore bar.
- Origin of Calcrete in Red Sediment from Visakhapatnam Coast, Andhra Pradesh
Authors
1 Department of Geology, Nagarjuna University, Nagarjunanagar 522510, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 29, No 4 (1987), Pagination: 459-464Abstract
Red sediment with calcrete is a characteristic deposit in the coastal tracts of Visakhapatnam region on the northeastern part of Andhra Pradesh. Three structural types of calcrete. rhizoconcretionary, mottled and massive, are recognized from Ramakrishna Mission, Rishikonda and Bhimilipatnam areas. Rhizoconcretionary calcrete is recorded from three profiles, but the mottled and massive are typically absent in Bhimilipatnam.
The origin of the various types of calcrete in the Visakhapatnam area is intimately linked to evapotranspiration of groundwater. The ischolar_mainlet origin of the calcrete structures is beyond doubt, as the actual woody tissue of the ischolar_main is occasionally found as a core to the rhizoconcretions.
The massive calcrete is precipitated much above the present day water table which, in general developed in the capillary-rise zone, indicating the rise in palaeo-water table. The well-developed calcrete profiles of Ramakrishna Mission and Rishikonda suggest the possible existence of a grove of old trees in the past. On the other hand, poorly developed calcrete profile of Bhimilipatnam indicates the palaeo-heath/scrub vegetation.