Summary Mannar sub basin of Cauvery basin is the southern- most of the Mesozoic rift basins existing along eastern continental margin of India and lies between Indian coast and Sri Lanka. The volcanic activities within Turonian sediments so typical of Gulf of Mannar are seen in almost all the drilled wells but have not been reported from any of the other sub basins of Cauvery basin. This is also reported in Pearl-1 well of Mannar sub basin in Sri Lankan offshore. Taking clue from the pattern of reflectors corresponding to intrusions, seismic study has been extended to the deeper part of Gulf of Mannar and also in its western part (towards Comorin ridge side) and observed the spread of this igneous activity which covers quite a large area. Recent dating through 40 Ar- 39 Ar studies carried out on one core sample of drilled well GM-E-A is around 89.1+0.65 Ma (Rathore et al., 2007). This age of the intrusive matches excellently with radiometric age for the Madagascar flood basalt province, the felsic volcanics of St Mary’s Island (SMI), two late Cretaceous mafic dykes around Huliyardurga, Karnataka and two regional dykes from Kerala region of South-western India. Together, therefore, the volcanic activities around these places may be associated with the break up of Greater India (India plus Seychelles) and Madagascar, envisaged to have occurred in Upper Cretaceous at 88Ma.
Abstract The Great Tsunami of 26 December 2004 is described using data from seven tide gauges in India and others from surrounding areas in the Indian Ocean. The tsunami struck the Indian east coast around 0330 UTC. The amplitude was 2 m above the tide at Chennai, Paradip, and Colombo. The east coast of India (and of Sri Lanka) was hit shortly after high tide; Tuticorin and Colombo, however, were hit shortly after low tide. The tsunami wave propagated northward along the Indian west coast. All these gauges are to the west of the earthquake zone and the detided sea levels show first a rise in sea level with the arrival of the tsunami, and then a sharp decrease. Spectral and wavelet analysis of the detided series show that the maximum amplitude was at a period of 35–45 minutes, with another maximum around 20 minutes. Along the Indian east coast, however, there is another broad peak between 1–2 hours within the first few hours after the first tsunami wave.
Abstract Petrochemical studies of granitoid rocks from the eastern part of Kumaun region suggest that the leading edge of India represents an active arc during Late Paleoproterozoic times. It has been observed that melt generation for granodiorite rocks from the eastern Almora Nappe and Chhiplakot klippe along with the Askot klippe was caused through a subduction‐related process involving hydrous partial melting of a Paleoproterozoic amphibole‐ and/or garnet‐bearing mafic source with the involvement of sediments from the subduction zone. The medium‐ to high‐K basic rocks, common in subduction‐related magmatic arcs, can also explain the generation of the high‐K granodiorites of the Chhiplakot klippe. The augen gneisses from the eastern Almora nappe and Chhiplakot klippe along with the Askot klippe further show geochemical similarity with the associated granodiorites, suggesting there is a genetic linkage with one another.
A brief account of the representative and workable industrial minerals namely magnesite, talc and barite in Lesser Himalaya, is presented here emphasizing their genesis. Deposits of magnesite and talc are found associated with Neoproterozoic, plateform type, shelf-slope limestone-dolomite host rocks from inner Lesser Himalayan sequences. Field, textural, geochemical signatures and fluid inclusions trapped in dolomite and magnesite reveal within basin processes, in an increased burial- diagenetic environment responsible for formation of magnesite replacing dolomite. Talc is formed at the expense of magnesite and silica, and with limited dolomite involvement at transition conditions from diagenetic to metamorphism. Barite deposit is hosted within Neoproterozoic Nagthat quartzite rocks of outer Lesser Himalaya, wherein its textures, fluid inclusion, sulfur and strontium isotopic studies helped in genetic understanding.
Fusarium oxysporum is main causative agent behind the most destructive soil-borne plant disease, fusarium wilt, which damages economically significant food crops like bananas, sweet potatoes, tomatoes, legumes and melons. Traditionally, the disease is controlled by physical and chemical methods that affect the environment adversely. One of the ecofriendly approach of plant disease prevention is biological control. Plant growth promoting rhizobacteria and endophytes are now consider as promising agent for disease control. In the present study bulb of Allium sativum plant were used for isolation of endophytes and the endophytes were screened for their bio-control potential. Thirteen bacterial endophytes (ESS01, ESS02, ESS03, ESS06, ESS023, ESS024, ESS025, ESS072, ESS073, ESS074, ESS075, ESS076 and ESS077) exhibited antifungal activity against Fusarium oxysporum f. sp. ciceris. All the isolates inhibited more than 59% mycelial growth on dual-culture assay. However isolate ESS01 and ESS02 exhibited higher antifungal activity (74.81% & 71.48%) against the pathogen Fusarium oxysporum f. sp. ciceris. Only five endophytic isolates (ESS01, ESS02, ESS023, ESS076 & ESS077) out of thirteen endophytes were selected for the pot experiment because of having plant growth promoting attributes and inhibiting more than 70% mycelia growth of Fusarium oxysporum. Biocontrol technique of production of plant against harmful pathogen is now a promising approach for ecofriendly and sustainable agriculture. In this context endophytic isolates were analysed for their antifungal properties especially on Fusarium oxysporum. The endophytic isolates Bacillus aerius ESS02, Bacillus velezensis ESS076, and Bacillus siamensis ESS077 significantly enhanced the plant biomass in chick pea plant even in presence of pathogen and eliminating the harmful effect of Fusarium oxysporum on chick pea plant. Overall, present investigation indicate that Allium sativum harbors various endophytic bacteria that possess excellent antifungal activity and can be used as bio-control agent to control wilt disease of various plants.
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