Non-pollen palynomorphs as potential palaeoenvironmental indicators in the Late Quaternary sediments of the west coast of India

摘要

Non-pollen palynomorphs (NPP) are organic-walled microfossils that one frequently come across in palynological preparations during pollen analysis. Like pollen and spores they are more resistant to corrosion, and as such they too get preserved but not destroyed during maceration using HF and other strong acids. They provide an alternative source of palaeo-information where there is scarcity of pollen and spores in the sediments. Records of NPP in the Late Quaternary sediments form a valuable addition to the pollen-spore data of the lagoonal sediments of Kerala and the pollen pauper deposits of Gujarat coast, as not much palynological data are available from the west coast of India. The occurrence of Botryococcus, Pediastrum and colonies of Rivularia (cyanobacteria) in the Holocene sequence has considerable significance to ascertain the hydrological changes associated with the evolution of lagoons of the Kerala basin. Glomus cf. fasciculatum and thecamoebians are useful in the interpretation of soil conditions associated with aridity/stressed environment along the Gujarat coast. The abundance of microscopic charcoal and charred epidermal fragments of Poaceae (grasses and like forms) is related to fireassociated events, including that of human impact. Thus, the palaeoenvironmental indicator value of NPP is evident from the Late Quaternary deposits of the west coast of India. Study of these non-pollen microfossils has helped develop a new database on them. Further, a combined approach of pollen and NPP allows for better understanding of palaeoecological changes and also to assess the relative importance of climate change during the Holocene.