Madhav Kumar

Palynostratigraphy of the subsurface sediments of Upper Assam Basin, India

The palynoflora and palynodebris content have been studied of a 3800 m deep well situated in the oil producing Tinali area in the Upper Assam basin of the Brahmaputra Valley, India. The well penetrated through Dhekiajuli Formation, Namsang Formation, Tipam, Surma and Barail Groups (Oligocene-Pleistocene). Microfloral change from Barail Group to Surma Group is distinct and indicates a more rich deltaic swamp vegetation during deposition of Barail Group than overlying sediments. The fluviatile Neogene sediments are poor in microfossils and indicative of comparatively drier conditions. Three informal zones have been proposed based on occurrance or abundance of palynofossils. Amorphous organic matter is dominant in the Barail Group and is gradually replaced by biodegraded terrestrial and black debris in the post-Barail sediments. Reworked Palaeozoic and Mesozoic palynofossils occur through out the sequence. Moreover, reworked Palaeocene and Eocene palynotaxa are also recovered from the post-Barail sediments. This phenomenon is related with the Himalayan orogenic movements.

Botryococcus from the early Eocene lignite mines of western India: inferences on morphology, taphonomy and palaeoenvironment

ABSTRACT Botryococcus, an important member of the planktonic algae, occurs in freshwater pools, lakes and occasionally in brackish-water lagoons, with wide distribution in tropical and temperate climate zones throughout the world. It is recognised as an oil-producing alga that is found in rock records from the Precambrian onwards. Here, this alga was retrieved from two different lignite mines of Rajasthan and Gujarat (western India), of early Eocene age. Apart from discussing its structural details, alterations in structures and preservation biases, this alga was used to reconstruct the depositional environment of the region based on its morphological and taphonomical characteristics. The images under transmitted light, fluorescence and scanning electron microscopy display aggregates of the irregular colonies, spherical to oval in shape, with cups arranged in definite patterns. The taphonomic characteristics of a large number of these algae indicate their autochthonous origin and in situ burial conditions. The dissolution of their outer layers suggests early diagenetic processes and loss of integrity due to microbial activity in the later phases of their burial in these sediments. The environment in the early Eocene has been reconstructed on the basis of the present findings, along with earlier recorded palynofacies from the region.

Plant remains from the Tharumsa Formation of Ladakh, India

Plant remains, including both mega and micro collected from the middle part of the Tharumsa Foramtion (early Miocene) are described for the first time from the Tharumsa village of the Kargil district, Jammu and Kashmir to reconstruct the palaeoenvironment. They indicate their affinities with Broussonetia of the Moraceae and Abies, Cedrus and Pinus of the Pinaceae. Their presence indicates warm and moist tropical to sub-tropical climate in the Kargil area during the depositional period against the cold and dry climate prevailing at present.

Pollen morphology of the coryphoid genus Licuala (Palmae)

Abstract Pollen morphology of nine species of the coryphoid genus Licuala Wurmb. (Palmae) is studied under light and scanning electron microscopes. The pollen grains have tectate exine with reticulate to microreticulate and punctate pattern. Exine stratification of similar type is also known in other coryphoid genera, e.g., Livistona, Sabal, Chamaerops, Corypha, Brahea and Washingtonia. Variations in the exine pattern in relation to the habitat of the plant is discussed.