Late Maastrichtian vegetation and palaeoclimate: Palynological inferences from the Deccan Volcanic Province of India

Abstract

Our understanding of the low latitude terrestrial climate of the late Maastrichtian is far from satisfactory. We have attempted to reconstruct the late Maastrichtian vegetation and climate of the Deccan Volcanic Province (DVP), central India. Palaeomagnetic results suggest that the Deccan lava flows were emplaced during the late Maastrichtian C29r magnetochron. Sedimentological studies reveal a swampy to shallow brackish lacustrine depositional setup in a warm and humid climate with low to moderate energy conditions. The floristic composition indicates an overall dominance of Arecaceae followed by Malvaceae and Ephedraceae. The vegetation prevailed under five palaeoecological associations viz., mangrove, coastal fringes, Tropical Rain Forests (TRFs), forest outliers and upland flora. The assemblage envelops taxa belonging to TRFs (54%), coastal (13%), tropical moist deciduous (13%), herbaceous (8%), mangrove (8%), and sub-tropical (4%) vegetation. The TRFs include taxa presently prevailing within the Western Ghats of India and in the TRFs of Africa. The Coexistence Approach (CA) analysis suggests a mean annual temperature of 24.5 ± 2.3 °C, cold month mean temperature of 18.5 ± 3.3 °C, warm month mean temperature of 27.5 ± 0.3 °C, mean annual precipitation of 1890.5 ± 208.5, precipitation during the wettest month 335 ± 15 mm, precipitation during the driest month 26 ± 7 and precipitation during the warmest month 111 ± 1. The inferred climatic conditions were apt for sustaining the high diversity within the close canopy multi-storeyed TRFs. The palaeoclimatic data also indicates a strong seasonality, and most likely, a monsoon type of climate during the late Maastrichtian of India.