Palaeoecological significance of a palynofloral assemblage from Surma Group (Late Miocene) of Tamenglong area, Manipur, northeast India

Abstract

A Late Miocene palynofloral assemblage is recorded for the first time from the sediments of Surma Group exposed at Tamenglong area of Manipur. The assemblage mainly consists of fungal spores and Microthyriaceous ascostromata, algal remains, pteridophytic spores, gymnospermous and angiospermous pollen. The quantitative analysis indicates the dominance of bisaccate gymnosperm pollen (61%) mainly represented by Podocarpidites and Pinuspollenites, followed by pteridophytic spores (23%), algal and fungal remains (11%) and angiosperm pollen grains (5%). Abundance of Hammenisporis spp., fungal conidia and ascostromata along with Zygnemataceous zygospores in the assemblage indicates a warm, humid climate and freshwater depositional environment for the Surma sediments in the present area of investigation. Recorded palynofloral assemblage with the characteristic fungal Microthyriaceous ascostromata suggests a pro-delta to shoreface depositional environment. Representatives of families Parkeriaceae, Cyatheaceae, Gleicheniaceae, Hymenophyllaceae, Podocarpaceae, Araceae and Malvaceae indicate the prevalence of tropical–subtropical climate. The Tamenglong palynofloral assemblage has been compared with some other assemblages known from the Mio-Pliocene sediments of India. The occurrences of abundant Pinuspollenites,Tsugaepollenites, Hibisceaepollenites and Parmathyrites in the present assemblage suggest a Late Miocene age.