Late Maastrichtian vegetation and palaeoclimate: Palynological inferences from the Deccan Volcanic Province of India
Résumé
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 VolcanicProvince (DVP), central India. Palaeomagnetic results suggest that the Deccan lava flows were emplacedduring the late Maastrichtian C29r magnetochron. Sedimentological studies reveal a swampy to shallowbrackish lacustrine depositional setup in a warm and humid climate with low to moderate energyconditions. The floristic composition indicates an overall dominance of Arecaceae followed by Malvaceaeand Ephedraceae. The vegetation prevailed under five palaeoecological associations viz., mangrove,coastal fringes, Tropical Rain Forests (TRFs), forest outliers and upland flora. The assemblage envelopstaxa 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 WesternGhats of India and in the TRFs of Africa. The Coexistence Approach (CA) analysis suggests a mean annualtemperature of 24.5 ± 2.3 C, cold month mean temperature of 18.5 ± 3.3 C, warm month mean temperatureof 27.5 ± 0.3 C, mean annual precipitation of 1890.5 ± 208.5, precipitation during the wettestmonth 335 ± 15 mm, precipitation during the driest month 26 ± 7 and precipitation during the warmestmonth 111 ± 1. The inferred climatic conditions were apt for sustaining the high diversity within theclose canopy multi-storeyed TRFs. The palaeoclimatic data also indicates a strong seasonality, and mostlikely, a monsoon type of climate during the late Maastrichtian of India.