Sediment depositional environment in some bays in central west coast of India

Abstract

Sediments in Kalbadevi and Mirya Bays are well sorted while those in Ratnagiri Bay are poorly sorted. Mean size of the sediments varies among the bays. Sediments in Kalbadevi Bay are both positively and negatively skewed while in Mirya Bay negatively and Ratnagiri Bay positively skewed. Kalbadevi sediments show high kurtosis values while those of Mirya Bay show medium and Ratnagiri Bay low values. Bivariant plots between various textural parameters predict mixed environments, viz. for Kalbadevi Bay: beach/river/barrier island/lagoon type; Mirya Bay: beach to barrier island type and Ratnagiri Bay: river to lagoon type. The abnormal values of kurtosis are attributed to such palimsest environment in these bays. The earlier reported heavy minerals data show a positive correlation with mean grain size in Kalbadevi Bay but negative correlation in Ratnagiri Bay, whereas they show an unharmonic relationship with sorting. Considering similar hydraulic conditions in all the bays, the existence of variation in the distribution of magnetite and ilmenite has been attributed to either a change in the depositional environment or different amount of input of sediments from a mixed provenance.