Constraints on the origin of south indian magnesite deposits

Most of the magnesite deposits in South India are confined to the southern part of the Dharwar craton and are associated with the ultramafics emplaced into the older supracrustal rocks. The major mineralisation is located in a shear zone that separates the Early Proterozoic and Pan-African granulites. The timing of mineralisation and the source of carbon for the various magnesite deposits of South India are points of debate. Temporal relations of deformation, metamorphism, incipient charnockitisation and mineralisation in the shear zone have been analysed. On the basis of the CO 2 influx, which favoured the formation of incipient charnockites, it is presumed that a juvenile CO 2 rich solution might have significantly contributed to the source of carbon for magnesite mineralisation. The present study attributes the timing of magnesite mineralisation to Pan-African time

Environmental impact assessment and environmental management plan - a case study of magnesite and dunite mine, South India

The Chalk Hills region of Salem, Tamil Nadu, South India, has been the producer of magnesite of both calcination and refractory grades, for more than a century. Due to the vein type nature of the mineralisation, mining of this white carbonate of magnesium involves employment of men and deployment of heavy earth moving machines. The host rock, dunite, is also being mined as it is a commercially valuable by-product. The mining activity, comprising drilling, blasting (both primary and secondary), loading of waste, transport of over burden and crushing of ore is having considerable impacts on the environment. Dust generation, noise levels and ground vibration were monitored as part of the Environmental Impact Assessment (EIA). Control measures recommended on the basis of findings of EIA are being practiced. Review studies were conducted to gauge the healing effects following the implementation of the Environmental Management Plan (EMP). Implementation of the EMP points towards the sustenance of a clean, safe and congenial working environment in the mine and its precincts

Magnetic fabrics in characterization of magma emplacement and tectonic evolution of the Moyar Shear Zone, South India

AbstractThe Moyar Shear Zone (MSZ) of the South Indian granulite terrain hosts a prominent syenite pluton (∼560 Ma) and associated NW-SE to NE-SW trending mafic dyke swarm (∼65 Ma and 95 Ma). Preliminary magnetic fabric studies in the mafic dykes, using Anisotropy of Magnetic Susceptibly (AMS) studies at low-field, indicate successive emplacement and variable magma flow direction. Magnetic lineation and foliation in these dykes are identical to the mesoscopic fabrics in MSZ mylonites, indicating shear zone guided emplacement. Spatial distribution of magnetic lineation in the dykes suggests a common conduit from which the source magma has been migrated. The magnetic foliation trajectories have a sigmoidal shape to the north of the pluton and curve into the MSZ suggesting dextral sense of shear. Identical fabric conditions for magnetic fabrics in the syenite pluton and measured field fabrics in mylonite indicate syntectonic emplacement along the Proterozoic crustal scale dextral shear zone with repeated reactivation history

Development of crystal lattice preferred orientation and seismic properties in Bhavani shear zone, Southern India.

Shear markers and shear sense indicators from the Bhavani shear zone (BSZ), a member of the south Indian Proterozoic shear system, separating the northern Archaean and southern Pan African granulite terranes, suggest multiphase reactivation. There is a progressive increase in mylonitisation corresponding to a progression in strain. The LS fabrics indicate near vertical principal flattening plane trending ENE-WSW, but with subvertical as well as subhorizontal stretching lineations implying a possible reactivation history with opposing movement vectors. Whilst the SEM-EBSD derived LPO of amphibole, biotite and feldspars suggest plastic deformation through the activation of intracrystalline slip systems, diffusional creep accommodated deformation can be inferred from the quartz LPO. All LPO suggest modifications in the fabric due to both retrograde and prograde reactivation during the tectono-thermal history of the BSZ over a period of nearly 2.0Ga. Petrofabric-derived seismic properties for the BSZ suggest that it exhibits a considerable seismic anisotropy, which reflects the petrofabrics of hornblende and biotite. Both LPO and seismic property observations imply conflicting tectonic X and Y directions, indicating possible superposition of contrasting X and Y vectors during different phases of the shear zone reactivation

Cultural and morphological studies on Ponnampet leaf and neck blast isolates of Magnaporthe grisea (Herbert) barr on rice (Oryza sativa L.)

The study was carried out to standardize the optimal growth, sporulation and production of perfect stage of pathogen on different media. Among different media used such as Potato dextrose Agar (PDA), Oat meal Agar, Ragi flour agar, yeast extract + 2% soluble starch, Host extract + 2% soluble sucrose agar, Potato dextrose agar + Biotin + Thiamine and Rice flour agar, Oat meal agar and potato dextrose agar was found to be best media for radial growth and sporulation of M. grisea. Maximum conidia length (9.46?m) and breadth (7.36?m) was recorded in Oat meal agar followed by Potato dextrose agar and least conidia length (6.15 ?m) and breadth (5.11 ?m) was recorded in ragi flour media after 20 days of inoculation. Conidial size varied in leaf and neck blast isolates, the maximum mean colony diameter of 88.00mm and 89.16mm in neck and leaf blast was recorded in Oat meal agar respectively. The maximum sporulation mean index was observed in Oat Meal agar of 3.15 ?m in leaf and 3.20 ?m in neck blast was recorded. The best growth of the pathogen was recorded at optimum pH range from 6.0 - 7.0 and temperature of 27oC. Therefore oat meal agar media was found to be best among all the media used for growth, sporulation, conidial size and colony characters of M. grisea

High biological productivity in the central Arabian Sea during the summer monsoon driven by Ekman pumping and lateral advection

Open oceans are generally oligotrophic and support less biological production. Results from the central Arabian Sea show that it may be an exception to this. We provide the observational evidence of fairly high biological production (up to 1700 mg C m-2 d-1) in the central Arabian Sea, along 64oE, during the summer monsoons of 1995 and 1996. The reasons for the observed high biological production, comparable to that from the traditionally well-known Somali upwelling region, were examined in light of the physical forcing and prevailing chemical fields. In the northern part of the central Arabian Sea, north of the axis of the Findlater Jet, upward Ekman pumping and entrainment driven by basin-wide winds along with advection of upwelled waters from the coastal region of Arabia supply nutrients to the upper layers. In the southern part, production is supported by nutrients advected from the Somali upwelling regio

Understanding our seas: National Institute of Oceanography, Goa

The present article summarizes the research done at the CSIR–National Institute of Oceanography in 2014 in ocean science, resources and technology. Significant research has been conducted on air–sea interactions and coastal circulation, biogeochemistry, biology, marine geophysics, palaeoceanography, marine fishery, gas hydrates and wave energy. Technological advances covered topics like oceanographic tools. Major strides have been made in marine resources research and evaluation

Understanding our seas: National Institute of Oceanography, Goa

The present article summarizes the research done at the CSIR–National Institute of Oceanography in 2014 in ocean science, resources and technology. Significant research has been conducted on air–sea interactions and coastal circulation, biogeochemistry, biology, marine geophysics, palaeoceanography, marine fishery, gas hydrates and wave energy. Technological advances covered topics like oceanographic tools. Major strides have been made in marine resources research and evaluation

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI