Palynological investigation of the tura formation (early eocene) exposed along the tura-dalu road, west Garo Hills, Meghalaya, India

Abstract

The present paper deals with the palynological study of the Tura Formation exposed along the Tura Dalu Road in West Garo Hills, Meghalaya. The recovered palynoflora is represented by dinoflagellate cysts, fungal remains, pteridophytic spores and angiosperm pollen. The assemblage is dominated by angiosperm pollen assignable to the families Arecaceae, Liliaceae, Oleaceae, Bombacaceae, Caesalpiniaceae, Mimosaceae, Unieaceae and Alangiaceae. Three new species of angiosperm pollen viz.. Retitricolpites singhii, Lanagiopollis meghalayaensis and Lanagiopollis subglobosus have been proposed. Pteridophytic spores, which constitute the subdominant clement of the assemblage, are assignable to the families Osmundaceae, Matoniaceae. Polypodiaceae. Sehizaeaceae and Parkeriaceae. Based on the quantitative analysis of the palynoflora, the studied sequence has been divided into three formal palynological assemblage zones. In ascending order, these are: (1) Lanagiopollis spp. Assemblage-zone (2) Palmidites spp. Assemblage-zone and (3) Tricolporopilites spp. Assemblage-zone. A comparison of the present assemblage with other Palaeogene assemblages of India indicates that it correlates well with those known from the upper pan of the Mikir Formation. Nonh Cachar Hills. Assam; the Prang Formation, Jaintia Hills Meghalaya; the Naredi Formation, Kutch; and the Rajpardi Lignite, Gujarat. Since these formations are of Early Eocene age, the studied sequence is also dated as Early Eocene. Most families represented in the assemblage are presently distributed in tropical to subtropical regions. indicating a similar climate during the deposition of Tura sediments. The presence of coastal elements and dinoflagellate cysts in the assemblage is indicative of a littoral depositional environment.