JOURNAL GEOLOGICAL SOCIETY OF INDIA Vol. 37, Jan. 1991, pp. 75 to 79 An Unusual E-vaporite Association from the Papaghni Group, Cuddapah Basin V. G. PHANSALKAR, ANAND S. KALE, N!TlN R. KARMALKAR AND VlVEK S. KALE Department of Geology, University of Poona, Pune 411 007 Abstract. The hitherto unreported occurrence of halite and gypsum casts from the Vempalle Formation is reported. Implications in terms of the early depositional history of the Cuddapah Basin is discussed. Keywords: Vempalle Formation, Cuddapah Basin, Papaghni Group. Evaporite, Andhra Pradesh. INTRODUC'IO\ In parts of Anantpur districtof Andhra Pradesh southof the Penner River and west of Tadpatri, sedimentary rocks of the Papaghni Group are exposed uncon formably resting on an eroded basement of the Archaean Peninsular Gneissic Complex, ithdipsof about l o-20towards cast. Figure I is a compositelitholog compiled on the basis of traverses inthe hill ranges north and south of the Anant pur-Tadpatri Road, around Maddalapalle (14'48'N: 77'49'IS"E) and Venkatapalle (14'47'20"N: 77'49'50''E). The basal siliciclastic sediments of the Gulcheru Quartzite Formation grade upwards,withinterfingeredand interbeddedrelationsinto the argilliticandcarbonate sequence of the Vempalle Formation. The dolomitic horizons are pervasively cherty and, at times, they are constituted entirelyofchertymaterial. Stromatolites attribtable to the form-species Crypto:oon, Kussie//a, andJacutophyton arerecogni able in these cherty-dolomitic beds (see also : Gururaja and Chandra, 1987). The sequence depicted in Figure 1 comprises the lower � 10% of the Vempalle Formation. Halite and gypsum casts are preserved on the beddingplanesoftheferruginous siltstones and follow impure dolomite from the basal horizons of the Vempalle Formation (see Fig. l). These horizons are best eposed in the hiII north of Maddalapalleandinthehill-range south of the toll gate on the Anantpur-Tadpatri Road. Halite casts (Fig. 2) are present on some of the bedding planes of the ferrugi nous siltstones at several positions inthe vertical sequence. Individual casts range in size from less than 5 mmtoabout 15mm. Theypredominantlydisplaythecubic form and are generally euhedralinature. The gypsumcasts(Fig.3)arepreserved as platy subhedral to euhedral crystal forms on the bedding planes of the cherty dolomites. They range in sizefromabout2mmtoover 30mmalong the length and 0016-7622/91/37-1-75/$ 1.00 © Gcol. Soc. India.