Metamorphic chronology of the Precambrian provinces of South India

1968 ◽  
Vol 5 (3) ◽  
pp. 591-600 ◽  
Author(s):  
U. Aswathanarayana
Keyword(s):  
South India ◽  
Regional Metamorphism ◽  
Southern India ◽  
Eastern Ghats ◽  
Cuddapah Basin ◽  
Upper Limit

There are three Precambrian provinces in southern India — the Dharwars (metavolcanics, metasediments, charnockites and granites), the Eastern Ghats (metasediments, charnockites and granites), and the Cuddapahs (essentially flat-lying continental sediments disturbed at the margins) — with chronostratigraphic histories dovetailing into one another. The Dharwars bear the impress of three episodes (about 3000 m.y., 2600–2300 m.y., and about 2000 m.y.) of folding, metamorphism, and emplacement of granites, the second being the most important. The pelitic sediments deposited in the Eastern Ghats geosyncline during the post-Dharwar times (upper limit, 2600 m.y.) were later folded and metamorphosed about 1600 m.y. ago into garnet-sillimanite-graphite gneisses (khondalites). Important deposits of mica pegmatites developed during this episode. Charnockites and granites associated with the Eastern Ghats were emplaced 1520–1300 m.y. ago. The Eastern Ghats rocks were subsequently cross-folded and metamorphosed about 500 m.y. ago. The sedimentation in the Cuddapah Basin was initiated sometime after the Eastern Ghats orogeny (1600 m.y. ago) but before 1160 m.y. ago. The Cuddapahs were subjected to regional metamorphism about 500 m.y. ago.

Prevalence and family factors associated with loneliness during COVID-19: A cross-sectional study from South India

2020 ◽  
Vol 3 (02) ◽  
pp. 61-67
Author(s):  
G. Sanjana ◽  
Vijaya Raghavan
Keyword(s):  
Online Survey ◽  
South India ◽  
Survey Design ◽  
Southern India ◽  
Related Factors ◽  
Cross Sectional ◽  
Health Crisis ◽  
Factors Associated ◽  
Family Discord ◽  
The Impact

Background: Loneliness can affect anyone at any point in their life. It can be detrimental to the wellbeing and quality of life of individuals and communities. In the ongoing COVID-19 pandemic, loneliness is considered as a public health crisis. Hence, the objectives of the study were to estimate the prevalence of loneliness and family related factors associated with loneliness among general population in south India. Materials and Methods: The study employed a crosssectional online survey design. The data was collected in the first phase of the lockdown in 2020 from adults in Southern India. Socio-demographic profile and family related variables were collected using a semistructured proforma. Loneliness was assessed by UCLA loneliness scale. Results: Of 573 total respondents to the survey, aged between 18-65 years, 43% were male and 57% were female. The overall prevalence of loneliness was 63% (358/573). No significant gender differences were observed in the prevalence of loneliness. Family discord was associated with higher rates of loneliness (p less than 0.01). Other factors associated were younger age and being single. Conclusion: Rates of loneliness during the COVID-19 lockdown were high in Southern India. Findings suggest that interventions should prioritize younger people. Increasing social support and improving interpersonal skills, which in turn would help reduce family discord and may reduce the impact of COVID-19 on loneliness.

scholarly journals Records of the Indian Sand Snake Psammophis condanarus (Merrem, 1820) (Reptilia: Lamprophiidae) in southern India

2017 ◽  
Vol 9 (7) ◽  
pp. 10453 ◽  
Author(s):  
S. R. Ganesh ◽  
Vivek Sharma ◽  
M. Bubesh Guptha
Keyword(s):  
New Records ◽  
Southern India ◽  
Eastern Ghats ◽  
Field Surveys ◽  
Voucher Specimens ◽  
Deccan Plateau

We present new records of the Indian Sand Snake Psammophis condanarus from southern India, where its existence has remained doubtful till date.  Our records are based on both live and preserved voucher specimens that are illustrated and described here.  We furnish distribution records of this species from two sites belonging to two different ecoregions in southern India—Tirupati in the Eastern Ghats and Hospete in the Deccan plateau.  Our work highlights the obscurity of certain, large-growing, diurnal land snakes that have as yet managed to evade the attention of field biologists largely due to a lack of field surveys in certain ecoregions. 

Addition of two pleurocarpous mosses to the Bryoflora of South India

2019 ◽  
Vol 42 (1) ◽  
pp. 99-103
Author(s):  
Neerja Pande ◽  
◽  
Priyanshu Srivastava ◽  
A.K. Asthana ◽  
◽  
...  
Keyword(s):  
Andhra Pradesh ◽  
South India ◽  
Eastern Ghats ◽  
Pleurocarpous Mosses

A recent exploration and study on bryophytes of Eastern Ghats’ area of Andhra Pradesh has revealed the occurrence of two pleurocarpous mosses viz., Thuidium assimile (Mitt.) A. Jaeger and Anomodon minor subsp. integerrimus (Mitt.) Iwatsuki as new addition to the moss flora of South India. A detailed morpho-taxonomical account and illustration of these taxa are provided.

A new species of Sparsorythus Sroka & Soldán, 2008 (Ephemeroptera: Tricorythidae) from Eastern Ghats of Southern India

Zootaxa ◽  
2021 ◽  
Vol 4915 (2) ◽  
pp. 237-245
Author(s):  
T SIVARUBAN ◽  
PANDIARAJAN SRINIVASAN ◽  
S BARATHY ◽  
M BERNATH ROSI ◽  
RAJASEKARAN ISACK
Keyword(s):  
New Species ◽  
Tamil Nadu ◽  
Abdominal Segment ◽  
Southern India ◽  
Eastern Ghats ◽  
Femur Length ◽  
Male And Female ◽  
Length Width ◽  
A New Species

A new mayfly species, Sparsorythus sivaramakrishnani sp. nov. from the stream of Pullian cholai, Thuraiyur, Namakkal district, Tamil Nadu, India is described based on male and female nymphs. Sparsorythus sivaramakrishnani sp. nov. differs from the closely related S. gracilis by the shape of the left prostheca, the number of bristle-like processes at base of left prostheca, the ratio and shape of right prostheca, the ratio of femur length: width, the size of the female nymph, the mesonotum overlapping in fifth abdominal segment of the female, and by the shape of hypopharyngeal lingua. 

scholarly journals Floristic Diversity and Vegetation Analysis of Plants from Various Forest Types in Hosur Forest Division, Tamil Nadu, Southern India

2018 ◽  
Vol 10 (4) ◽  
pp. 597-606
Author(s):  
Umeshkumar L. TIWARI ◽  
Kaliamoorthy RAVIKUMAR
Keyword(s):  
Species Diversity ◽  
Tamil Nadu ◽  
Diversity Index ◽  
Southern India ◽  
Eastern Ghats ◽  
Composition Analysis ◽  
Floristic Diversity ◽  
Forest Types ◽  
Diversity Assessment ◽  
Forest Division

The study deals with the floristic diversity assessment and vegetation composition analysis in various forest types from Hosur Forest division situated in Eastern Ghats of Southern India, in the state of Tamil Nadu. The study recorded 468 species of plants belonging to 283 genera and 91 families, including Angiosperms (464 species), Pteridophytes (3 species) and Bryophytes (1 species). Of the total, 94 species are trees, 12 are lianas, 70 are shrubs, 34 species are climbers, 194 species are herbs, sedges 7, grasses 21, ferns 3 and 1 species of moss. The five most abundant families in Hosur Forest Division were Fabaceae (45 spp.), Poaceae (34 spp.), Acanthaceae (30 spp.), Euphorbiaceae (28 spp.) and Rubiaceae (25 spp.). The quantitative features such as density and important value index (IVI) varied greatly among forest and in different forest types. In the present study, the diversity index of shrubs and herbs were found to be higher than that of trees. The maximum species diversity was recorded in Southern dry mixed deciduous forest (SDMDF) followed by Southern Thorn Forest (STF) and Southern Thorn Scrub (STS). The species diversity (H) was recorded the highest for SDMDF (5.61) followed by STF (5.18) and the lowest for STS (5.12). The presence of large number of higher girth class tree species and low number of sapling and seedling indicates that the present forests investigated are old and exhibiting low regeneration.

Origin of corundum within anorthite megacrysts from anorthositic amphibolites, Granulite Terrane, Southern India

2020 ◽  
Vol 105 (8) ◽  
pp. 1161-1174
Author(s):  
Shreya Karmakar ◽  
Subham Mukherjee ◽  
Upama Dutta
Keyword(s):  
High Pressure ◽  
Grain Boundaries ◽  
Chemical Potential ◽  
Regional Metamorphism ◽  
Phase Relations ◽  
Southern India ◽  
Triple Junctions ◽  
Medium Temperature ◽  
Hp Metamorphism ◽  
Basic Rocks

Abstract Growth of corundum in metamorphosed anorthosites and related basic-ultra-basic rocks is an exceptional feature, and its origin remains elusive. We describe the occurrence of and offer an explanation for the genesis of corundum in anorthositic amphibolites from ~2.5 Ga old basement of the Granulite Terrane of Southern India (GTSI). The studied amphibolites from two localities, Manavadi (MvAm) and Ayyarmalai (AyAm), contain anorthite lenses (An90–99) with euhedral to elliptical outline set in a finer-grained matrix of calcic plagioclase (An85–90) and aluminous amphibole (pargasite-magnesiohastingsite). The lenses, interpreted as primary magmatic megacrysts, and the matrix are both recrystallized under static condition presumably during the regional high pressure (HP) metamorphism (~800 °C, 8–11 kbar) at ~2.45 Ga. Corundum occurs in the core of some of the recrystallized anorthite lenses (An95–99) in two modes: (1) Dominantly, it forms aggregates with magnetite (with rare inclusion of hercynite; in MvAm) or spinel (and occasionally hematite-ilmenite; in AyAm). The aggregates cut across the polygonal grain boundaries of the anorthite and contain inclusions of anorthite. (2) Corundum also occurs along the grain boundaries or at the triple junctions of the polygonal anorthite grains, where it forms euhedral tabular grains, sieved with inclusions of anorthite or forms skeletal rims around the recrystallized anorthite, such that it seems to be intergrown with anorthite. Combined petrological data and computed phase relations are consistent with growth of corundum in an open system during regional metamorphism in the presence of intergranular fluids. Two mechanisms are proposed to explain the formation of the corundum in the amphibolites: (1) corundum + magnetite/spinel aggregates formed dominantly by oxy-exsolution of pre-existing Al-Fe-Mg-(Ti)-spinel. This pre-existing spinel may be primary magmatic inclusions within the anorthite phenocrysts or could have formed due to reaction of primary magmatic inclusions of olivine with the host anorthite. Pseudosections of fO2-nH2O-T-P in the CaO–FeO–MgO–Al2O3–SiO2–H2O (CFMASH) system indicate that fO2 and H2O strongly influence the formation of corundum + amphibole from the initial magmatic assemblage of anorthite (phenocrysts) + spinel ± olivine (inclusions). (2) The corundum with anorthite presumably formed through desilification and decalcification of anorthite, as is indicated by computed phase relations in isobaric-isothermal chemical potential diagrams (µSiO2-µCaO) in parts of the CASH system. Growth of corundum in this mode is augmented by high activity of anorthite in plagioclase, high pressure, and low-to-medium temperature of metamorphism. This study thus presents a new viable mechanism for the origin of corundum in anorthositic amphibolites, and basic-ultra-basic rocks in general, which should provide new insight into lower crustal processes like high-pressure metamorphism.

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