Late Triassic palynoflora from the Pranhita–Godavari Valley,India: evidence from vertebrate coprolites

Vijaya, Prasad, G.V.R. & Singh, K., June, 2009. Late Triassic palynoflora from the Pranhita–Godavari Valley, India: evidence from vertebrate coprolites. Alcheringa 33, 91–111. ISSN 0311-5518.

The Upper Triassic Maleri Formation, represented by red clays and sandstones, has to date not produced any plant macrofossils or palynomorphs. Many spiral and non-spiral coprolites collected during this study from the Maleri Formation of the Pranhita-Godavari Valley were analysed for palynomorphs. Based on shape, nature of coiling and size, the Maleri coprolites are classified into seven groups. Of these, only Group-I, Type 5 (non-spiral) and amphipolar (spiral) types yielded diverse gymnospermous and pteridophytic spores, pollen, other plant debris and sparse fungal spores and algal remains. Occurrences of Antulsporites varigranulatus, Aratrisporites spp., Cadargasporites baculatus, Dubrajisporites isolatus, Enzonalasporites vigens, Foraminisporis coelatus, Grandispora spinosa, Kraeuselisporites saeptatus, Polycingulatisporites reduncus, Staurosaccites spp., Tethysispora unica and Tikisporites balmei confirm a Late Triassic age for the coprolite-bearing red clays. Records of Classopollis classoides and Callialasporites turbatus/dampieri in these assemblages more precisely suggest a Norian to Rhaetian age. The non-spiral coprolites were possibly produced by aquatic piscivorous animals whereas the spiral coprolites may have been produced by an as yet unidentified fish taxon. The coprolite-producing animals (spiral and non-spiral groups) possibly ingested gymnospermous and pteridophytic plant remains passively along with water or their herbivorous prey.     

Oligocene-Miocene palynomorphs from subsurface sediments,West Bengal,India

Palynological studies of Cenozoic sediments from borehole PGD-1A in the easternmost extension of the Damodar Basin, West Bengal, India, provide important new palynological data from this basin, where previous data are rare. The palynoassemblage includes Striatriletes, Crassoretitriletes, Bacutriporites, Cauveripollis, Cheilanthoidspora, Palaeomalvaceaepollis, Tricollareporites, Pinuspollenites and Tsugaepollenites which suggest a late Oligocene - early Miocene age. Dinocyst genera such as Selenopemphix, Tuberculodinium, Hystrichokoipoma and Thalasiphora, recorded from the borehole, also support this age assignment. The assemblage indicates a tropical to subtropical humid climate with high rainfall. Deposition of the studied strata took place in a delta under shallow marine influence; this is the first evidence that a marine transgression extended into the Damodar Basin and that mangrove forest developed in the area.     

Palynology of the Jurassic-Cretaceous transition in the Rajmahal Formation,West Bengal,India

Borehole PGD-1A penetrated Cretaceous Rajmahal Formation and underlying Triassic Panchet Formation between 288–423.51 m. Palynoassemblages recovered within the Mesozoic sequence are assigned to three palynozones closely comparable to Australian assemblages. The oldest palynozone is the Verrucosisporites-Lundbladispora zone, which occurs between 373.5–376 m in the uppermost Panchet Formation. The first occurrence of Callialasporites turbatus occurs at 373.5 m and signals the presence of Jurassic deposits. The overlying Infratrappean greyshales (371.5–354 m) of the Rajmahal Formation is represented by the Murospora florida palynozone of Late Jurassic age. The youngest palynozone identified is the Cicatricosisporites australiensis zone which occurs within the Inter-trappeans (346.35–295.0 m) of the Rajmahal Formation. Based on ages assigned to the M. florida and C. australiensis zones in Australia, the Rajmahal Formation is dated as Oxfordian-Berriasian. The first appearance datums (FADs) of Cicatricosisporites australiensis, Crybelosporites stylolsus, Aequitriradites spinulosus and Lycopodiacidites dettmannae suggest that the Jurassic-Cretaceous boundary probably lies just within the interval 346.35–328.81 m in Inter-trappean bed II.