Petrographic Characteristics and Depositional Environment of the No. 9 Coal (Pennsylvanian) from the Anjialing Mine, Ningwu Coalfield, China

et al. 2017

Int J Coal Sci Technol

Lignite samples collected from Vastan, Rajpardi and Tadkeshwar lignite mines of Cambay basin (Gujarat) were subjected to organic petrographic investigations and geochemical analyses and the data, thus generated, is used to reconstruct the paleodepositional history of these lignite sequences. The lignites of Cambay basin dominantly comprise huminite maceral group (71.6%-86.3%) followed by liptinite (10.1%-19.3%) and inertinite (3.6%-11.0%) maceral groups. The mineral matter varies from 9.0% to 20.0%. The petrography based facies model indicates that these lignites have high values of gelification index (GI) and low tissue preservation index revealing a continuous wet condition in the basin and a relatively slower rate of subsidence during the decay of organic matter. On several occasions, during the formation of seams in Tadkeshwar, Rajpardi and Vastan mines, the value of GI exceeded 10 which indicates a forest permanently flooded and the cause of pronounced degree of degradation. However, few sections in Tadkeshwar seam had relatively drier spells of environmental conditions due to fluctuation in the water table as revealed by moderately high content of inertinite macerals. This is specially indicated by the occurrence of funginite which normally thrives in the upper oxygenated peatigenic layer and indicates prevalence of oxic conditions during plant deposition. Such conditions prevailed during a transgressive phase but there were intermittent fluvial activities also giving rise to supratidal flood plain as reflected in the form of associated carbonaceous shales in the basin.

Section: Paleomiresmentioning

confidence: 99%

Petrographic characteristics and paleoenvironmental history of Eocene lignites of Cambay basin, Western India

et al. 2017

Int J Coal Sci Technol

“…Teichmüller (1989) has demonstrated that the presence or absence of macerals is indicative of the paleo-depositional environment. Nevertheless, these macerals acquire various characteristics through peat-forming plant communities, nutrient supply, bacterial activity, types of deposition, temperature, pH, and redox potential (Teichmüller et al 1998a, b;Lin and Tian 2011). Surface inundation in the basin relates to increase in the clastic mineral matter (Singh and Singh 1996).…”

Section: Depositional Environmentmentioning

confidence: 99%

Understanding the paleomires of Eocene lignites of Kachchh Basin, Gujarat (Western India): petrological implications

et al. 2017

Int J Coal Sci Technol

The present paper entails the results of the investigations carried out on the lignite deposits of Kachchh Basin. The lignite samples were drawn from five lignite seams from Panandhro lignite field (Seam-I to -V) and eight lignite seams (Seam-I to -VIII) from the Matanomadh lignite field which are currently operational. The petrographic analysis of the lignites indicates a dominance of huminite group of macerals which is mainly contributed by ulminite-A, ulminite-B, attrinite, densinite, and phlobaphinite. Liptinite (chiefly sporinite, cutinite, resinite, and liptodetrinite) and inertinite (chiefly fusinite, funginite, and inertodetrinite) groups occur in subordinated amount. The mineral matter occurs in moderate concentration. Though sulfur content is high in these lignites, there is no fixed trend of variation of sulfur from bottom seam to top seam. The investigation reveals a flooded forest swamp having high rate of degradation. However, there were a few drier periods indicated by relatively more inertinite macerals. The petrography-based models indicate that the Kachchh lignites of Gujarat evolved in coastal marshy setting under transgressive phase. However, there were few intermittent fluvial activities giving rise to supratidal flood plain. This led to the formation of the associated carbonaceous shales in the basin.

“…This eventually led to the luxuriant growth of flora and development of peat swamps. Lin and Tian (2011) demonstrated that the depositional environment determines the composition as well as the preservation of peat and coal. 'Coal facies' is defined as primary genetic types of coal and is dependent on the paleoenvironmental conditions allowing the accumulation of precursor peat (Teichmüller, 1982).…”

Section: Evolution Of Coals 421 Formation Of Foredeepmentioning

confidence: 99%

Petrological Investigations of Oligocene Coals from Foreland Basin of Northeast India

Energy Exploration & Exploitation

2013

The results of the petrological investigations carried out on coal samples from the Oligocene deposits of Northeastern India (Assam, Arunachal Pradesh and Nagaland) have been discussed. These deposits occur in the Tikak Parbat Formation (Barail Group) and were probably deposited in the foreland basin. Petrographically, these coals are enriched in vitrinite macerals (65.8-96.6 vol %, mean 87.2 vol %) with variable concentrations of liptinite macerals (2.7-35.4 vol %, mean 11.9 vol %). They contain low concentration of inertinite (nil-3.3 vol %, mean 0.9 vol %) macerals. The microlithotype is dominated by vitrite (61.5-100 vol %, mean 90.8 vol %). An elevated volatile matter (44.15 -60.20 wt %, mean 52.90 wt %, d.a.f. basis) and reflectance values (VRr 0.39-0.61%) put their rank as sub-bituminous type 'C' to high volatile bituminous type 'C'. The GI and TPI values favour telmatic conditions of origin with high tree density and prolonged wet conditions. This is in agreement with the paleoenvironment interpreted from the vitrinite and liptinite-rich microlithotypes, which suggested a forest and reed facies. However, the presence of inertinite in some coal seams indicates tectonic upheavals / regression of the sea resulting to periodic and short span dryness of the basin.