Alpana Singh

The Neyveli lignite deposits (Cauvery basin), India : organic composition, age and depositional pattern

Abstract The palynological, particulate organic material (palynodebris) and biopetrological aspects of the main lignite seam encountered in NLE-27, NLE-35 and NLE-36 borehole sections in mine III of the Neyveli lignite field of the Cauvery basin were investigated. The palynoflora is rich in angiospermic pollen (79.6%) distributed in 33 genera ( and 86 species). Pteridophytic (spores) representation is only 20.4% with 5 genera (and 9 species). Quantitatively, palynofossil assemblage of the seam from mine III resembles fairly well with those from the mines I and II. Based on geological, geophysical and palynological data the lignite seam has been assigned a Miocene age. The lignite seam has a very high proportion of structured terrestrial organic matter (OM) with a subordinate amount of biodegraded terrestrial, fungal and amorphous materials, in addition to resin. Petrologically, the seam is rich in the huminite group of macerals, usually dominated by attrinite, densinite (humodetrinite) macerals. Botryococcus is common, as are framboidal pyrite and concretions. The seam in mine III is lower in rank (Ro max 0.39%) than its counterpart in mine I (Ro max. 0.47%). From a critical assessment of the palynological, palynodebris and biopetrological data, together with published geological information, it is assumed that the main lignite seam was formed from in situ mangrove-mixed moist tropical forests vegetation, probably in a lagoon on a prograding delta with freshwater inlets from the western and restricted seawater channels from the east.

Trilatiporate pollen from Indian Palaeogene and Neogene sequences: evolution, migration and continental drift

Abstract The diagnosis of the genus Dorreenipites Biswas, 1962, incorporating heteropolar pollen with sub-equatorial pores, is emended to include morphological details observed on pollen recovered from the Miocene lignite, Neyveli, Tamil Nadu, India. A new genus Retitrilatiporites is proposed to assimilate trilatiporate pollen from Palaeocene-Eocene sediments of Kutch, which are distinct in having feeble pore-bearing projections, ± equatorial pores, and a smaller size. A speciation scheme for both trilatiporate genera is proposed based on significant morphological features, namely well-developed vs. feeble pore-bearing projections, and exine structure varying from psilate to reticulate on one or both poles. Evolutionary trends of these taxa in Africa and India and their stratigraphic significance are discussed, from the perspective of their migration and extinction, which was controlled by the northward drift of the Indian plate. Four new species and five new combinations are proposed, and the botanical relationship of this pollen type is discussed.

Petrographic and Depositional Characteristics of Tadkeshwar Lignite Deposits (Cambay Basin), Gujarat

Tadkeshwar lignite deposits are one of the important Lower Tertiary lignite deposits of Cambay Basin, Gujarat. These lignites are rich in huminite macerals followed by liptinite and inertinite with moderate to high proportions of associated mineral matter. Under fluorescence mode these are found to be rich in liptinite macerals, in particular the liptodetrinite and resinite. The type of huminite suggests that the lignite is formed from mixed vegetal source, i.e. woody forest vegetation and herbs, shrubs. The composition of macerals indicates the deposition of lignite in sub-aqueous condition in wet-reducing environment with intermittent exposure and subsidence of the peat surface. The rank of the Main and the Leader seams, determined through reflectance measurement, indicate that the lignite is less mature. The considerable amount of perhydrous huminite may have contributed to the lower reflectance values in some of the samples. Low rank and appreciable amount of mineral matter make the lignite suitable for its utilization in thermal power plants, however when upgraded or mixed with better quality coals it can be used for other industries.

Observations on Indian Permian Gondwana Coals Under Fluorescence Microscopy: An Overview

Abstract Macerals like sporinite, cutinite, suberinite and resinite of the liptinite group have been insufficiently recorded in Indian Permian Gondwana coals, until the fluorescence microscopy came into existence. With the introduction of this technique, macerals like bituminite, fluorinite and exsudatinite were convincingly recognized and alginite and liptodetrinite, normally mistaken for mineral matter under normal reflected light in routine coal petrographic analysis, were identified with certainty. Thus, fluorescence microscopy has added certain new macerals to the tally of the liptinite group and has increased their overall proportion in Indian Gondwana coals. In addition to the liptinite group, collodetrinite (=desmocollinite) and a certain fraction of collotelinite (=telocollinite) macerals of the vitrinite group were found to be fluorescing with dull reddish-brown to dark brown colours. Certain semifusinite and inertodetrinite macerals of inertinite group were also found to fluoresce with almost identical intensity and colour as that of the associated perhydrous (fluorescing) vitrinite. Contributions of degraded resinite, algal matter and bitumen in the formation of perhydrous vitrinite have been established. The fluorescence behaviour of inertinite appears to be related with its genesis from partial oxidation of resin/bitumen-impregnated cell walls.

Revision of some Tertiary pollen genera and species

Abstract Three fossil pollen genera Dakshinipollenites Navale and Misra (1979), Grevilloideaepites Biswas (1962) and Jacobipollenites Ramanujam (1966) reported from Tertiary sediments of India, are revised. Vellaripollis gen. nov., four new species: Vellaripollis foveolatus, Jacobipollenties magniporus, J. distinctus, J. crassimurus and to new combinations: Grevilloideaepites inferius and G. pachyexinus are proposed.

A new spinose monosulcate genus Spinomonosulcites and an emendation of spinose porate Acanthotricolpites

Abstract Spinose monosulcate and spinose porate pollen of form genera Neocouperipollis and Acanthotricolpites recorded from Tertiary sediments of India, are critically evaluated. The type specimen Neocouperipollis kutchensis has pores rather than sulcus as previously considered. Moreover, both monosulcate and porate species have been described under the genus Neocouperipollis . The spine morphology and the nature of spine attachment with the exine in spinose porate pollen are different from those of the spinose monosulcate pollen. The type species Neocouperipollis kutchensis is transferred here to Acanthotricolpites . A new genus Spinomonosulcites is proposed here to accomodate monosulcate species of Neocouperipollis. Acanthotricolpites , found to be porate instead of colpate, is emended here.

New colporate pollen taxa from Neyveli lignite, South India

Four new pollen genera: Bacuspinulopollenites, Cuddaloripollis, Scrobiculatricolporites, Tamilipollenites and seven new species from the subsurface lignite samples of the Mine III area of the Neyveli Lignite Field are described. Tricolporopilites (Kar and Saxena) Kar 1985 is emended and three new species T. uniformis, T. differentialis and T. tectatus are assigned to it. These colporate angiospermous pollen taxa provide additional information on the palynofloral composition of the main lignite seam encountered in three boreholes.

Characterization of Panandhro Lignite Deposits (Kachchh Basin), western India: Results from the Bulk Geochemical and Palynofloral Compositions

Characterization of the Panandhro lignite deposits from western Indian state of Gujarat, based on the geochemical and palynological evidences, has been performed to assess the floral composition, maturity and hydrocarbon potential of the sequence. Elementally, the lignites consist of moderate carbon, low hydrogen and moderate sulfur contents. The samples are characterized by high TOC contents (lignite: av. 46.43 wt.%, resin: 62.47 wt.%). The average HI values for the lignite is 136 mg HC/g TOC, and that of the associated resin is 671 mg HC/g TOC. The highest Tmax is recoded in lignite (422°C) and lowest in the resin (39°C) samples. The FTIR spectrum of lignite is characterized by highly intense OH stretching peak ~3350 cm-1, aliphatic CHx stretching peaks between 3000-2800 cm-1, aromatic C=O stretching and an aromatic C=C stretching. The spectrum of resin shows strongest absorption due to aliphatic CHx stretching between 2940-2915 cm-1 and 2870-2850 cm-1, and deformation by the medium peak between 1450 and 1650 cm-1. The recovered palynofloral assemblage indicates the dominance of angiosperm pollen grains with maximum abundance of Arecaceae family, and subdominant pteridophytic spores. Marine influence is indicated by the presence of abundant dinoflagellate cysts. The occurrence of flora from a variety of ecological niches suggests a luxuriant diverse vegetation pattern existed in the vicinity of depositional site under humid tropical conditions. The overall characteristics of the lignite deposits point towards their ability to generate (upon maturation) hydrocarbons as they have types III–II admixed kerogen (organic matters).

Effect of long-term fertilization and cropping on the potassium supplying capacity of soils

Soil samples from a long term field experiment, to study the K depletion pattern, were analysed for K. The values of supply parameters pK−1/2p (Ca+Mg) and free energy δGr0 were calculated using the data on water soluble and exchangeable cations. Correlation coefficient values between pK−1/2p (Ca+Mg) vs. total K removed, K removal by pearl millet in 1980 and soil available potassium were positive and statistically significant. This indicated that these soils have reached the stage where they would start responding to potassium application. Also, negative but significant correlation of δGr0 with pK−1/2p (Ca+Mg) and available K, were found. δGr0 values were positive indicating the affinity of such soils for K and the values, for K fertilized plots were lower in comparison to plots where no K was applied. pK−1/2p (Ca+Mg) parameter was found to be a better measure of K availability over δGr0 due to either fixation of K or greater contribution of nonexchangeable K fraction towards plant utilized K.

On a striking fluorescing microcomponent from Indian Tertiary lignites

While analysing the Tertiary lignites from Neyveli (Miocene) and Panandhro (Eocene) lignite fields of India under fluorescence mode, an unusual fluorescing microcomponent, hitherto of unknown botanical affinity, has been recorded. Distinct morphological features and mode of occurrence preclude its inclusion in existing fluorescing macerals of the liptinite group. The paper provides information on petrographic and morphographic properties of the recorded fluorescing microcomponent, besides its significance.