scholarly journals An Overview of the Carbonatites from the Indian Subcontinent

2020 ◽  
Vol 12 (1) ◽  
pp. 85-116 ◽  
Author(s):  
Kirtikumar Randive ◽  
Tushar Meshram
Keyword(s):  
Sri Lanka ◽  
Indian Subcontinent ◽  
Source Rocks ◽  
Time Range ◽  
Alkaline Complex ◽  
Comprehensive Information ◽  
Igneous Origin ◽  
Continental Rifts ◽  
Low Degrees ◽  
Orogenic Belts

AbstractCarbonatites are carbonate-rich rocks of igneous origin. They form the magmas of their own that are generated in the deep mantle by low degrees of partial melting of carbonated peridotite or eclogite source rocks. They are known to occur since the Archaean times till recent, the activity showing gradual increase from older to younger times. They are commonly associated with alkaline rocks and be genetically related with them. They often induce metasomatic alteration in the country rocks forming an aureole of fenitization around them. They are host for economically important mineral deposits including rare metals and REE. They are commonly associated with the continental rifts, but are also common in the orogenic belts; but not known to occur in the intra-plate regions. The carbonatites are known to occur all over the globe, majority of the occurrences located in Africa, Fenno-Scandinavia, Karelian-Kola, Mongolia, China, Australia, South America and India. In the Indian Subcontinent carbonatites occur in India, Pakistan, Afghanistan and Sri Lanka; but so far not known to occur in Nepal, Bhutan, Bangladesh and Myanmar. This paper takes an overview of the carbonatite occurrences in the Indian Subcontinent in the light of recent data. The localities being discussed in detail cover a considerable time range (>2400 Ma to <0.6 Ma) from India (Hogenakal, Newania, Sevathur, Sung Valley, Sarnu-Dandali and Mundwara, and Amba Dongar), Pakistan (Permian Koga and Tertiary Pehsawar Plain Alkaline Complex which includes Loe Shilman, Sillai Patti, Jambil and Jawar), Afghanistan (Khanneshin) and Sri Lanka (Eppawala). This review provide the comprehensive information about geochemical characteristics and evolution of carbonatites in Indian Subcontinent with respect to space and time.

Suicide on the Indian Subcontinent

Crisis ◽  
2002 ◽  
Vol 23 (3) ◽  
pp. 104-107 ◽  
Author(s):  
Murad M. Khan
Keyword(s):  
Sri Lanka ◽  
Mental Health Professionals ◽  
Indian Subcontinent ◽  
Interpersonal Relationship ◽  
Public Health Problem ◽  
Elderly Subjects ◽  
Important Public Health Problem ◽  
Policy Makers ◽  
Formidable Challenge ◽  
Causative Factors

Summary: The Indian subcontinent comprises eight countries (India, Pakistan, Bangladesh, Nepal, Sri Lanka, Afghanistan, Bhutan, and the Maldives) and a collective population of more than 1.3 billion people. 10% of the world's suicides (more than 100,000 people) take place in just three of these countries, viz. India, Sri Lanka, and Pakistan. There is very little information on suicides from the other four countries. Some differences from suicides in Western countries include the high use of organophosphate insecticides, larger numbers of married women, fewer elderly subjects, and interpersonal relationship problems and life events as important causative factors. There is need for more and better information regarding suicide in the countries of the Indian subcontinent. In particular, studies must address culture-specific risk factors associated with suicide in these countries. The prevention of this important public health problem in an area of the world with myriad socio-economic problems, meager resources, and stigmatization of mental illness poses a formidable challenge to mental health professionals, policy makers, and governments of these countries.

Revision of the bamboo leafhopper tribe Mukariini (Hemiptera: Cicadellidae: Deltocephalinae) from the Indian subcontinent with description of new genera and species

Zootaxa ◽  
2019 ◽  
Vol 4547 (1) ◽  
pp. 1
Author(s):  
C.A. VIRAKTAMATH ◽  
M.D. WEBB
Keyword(s):  
Sri Lanka ◽  
Type Species ◽  
Tamil Nadu ◽  
Andhra Pradesh ◽  
West Bengal ◽  
New Records ◽  
Indian Subcontinent ◽  
Madhya Pradesh ◽  
New Genera ◽  
New Subgenus

Leafhopper genera and species of the tribe Mukariini from the Indian subcontinent are revised. Nine genera and 22 species including two new genera, one new subgenus and 12 new species are dealt with. The new taxa described are Aalinga gen. nov. with its type species Aalinga brunoflava sp. nov. (India: Andaman Islands), Buloria indica sp. nov. (India: Karnataka). Buloria zeylanica sp. nov. (Sri Lanka), Flatfronta bella sp. nov. (India: Karnataka; Bangladesh), Mohunia bifurcata sp. nov. (Myanmar), Mukaria omani sp. nov. (India: Gujarat, Karnataka, Madhya Pradesh), Mukaria vakra sp. nov. (India: Karnataka), Mukariella gen. nov. with its type species Mukariella daii sp. nov. (India: Manipur), Myittana (Benglebra) cornuta sp. nov. (India: Karnataka), Myittana (Myittana) distincta sp. nov. (India: Karnataka), Myittana (Savasa) subgen. nov. with its type species Myittana (Savasa) constricta sp. nov. (India: Andhra Pradesh, Gujarat, Haryana, Himachal Pradesh, Karnataka, Madhya Pradesh, Punjab, Tamil Nadu, Uttarakhand) and Scaphotettix arcuatus sp. nov. (India: West Bengal, Meghalaya, Mizoram). Genera Buloria Distant (new placement), Crispina Distant (new placement) and Myittana Distant (new placement) are placed in the tribe Mukariini. Genus Mohunia is redefined based on the study of its type species. Benglebra Mahmood & Ahmed 1969 is synonymised with Myittana Distant 1908 and considered as its subgenus. Myittana (Benglebra) alami (Mahmood & Ahmed) comb. nov., Myittana (Savasa) bipunctata (Mahmood & Ahmed) comb. nov.. Myittana (Benglebra) introspina (Chen & Yang 2007) comb. nov. and Mukariella bambusana (Li & Chen) comb. nov. are proposed; the first two species were earlier placed in the genus Benglebra, the third species in the genus Mohunia and the fourth in the genus Mukaria. Genera Flatfronta Chen & Li and Myittana are new records for India and Scaphotettix striata Dai & Zhang is a new record for the Indian subcontinent and Sri Lanka. All taxa dealt with are described and illustrated and keys for genera and their species are also given. 

Petrologic and thermal constraints on the origin of leucogranites in collisional orogens

2004 ◽  
Vol 95 (1-2) ◽  
pp. 73-85 ◽  
Author(s):  
Peter I. Nabelek ◽  
Mian Liu
Keyword(s):  
Partial Melting ◽  
Shear Zones ◽  
Source Rocks ◽  
Radioactive Isotopes ◽  
The Usa ◽  
Appalachian Orogen ◽  
Shear Heating ◽  
Heating Model ◽  
Orogenic Belts ◽  
Collisional Orogens

ABSTRACTLeucogranites are typical products of collisional orogenies. They are found in orogenic terranes of different ages, including the Proterozoic Trans-Hudson orogen, as exemplified in the Black Hills, South Dakota, and the Appalachian orogen in Maine, both in the USA, and the ongoing Himalayan orogen. Characteristics of these collisional leucogranites show that they were derived from predominantly pelitic sources at the veining stages of deformation and metamorphism in upper plates of thickened crusts. Once generated, the leucogranite magmas ascended as dykes and were emplaced within shallower parts of their source sequences. In these orogenic belts, there was a strong connection between deformation, metamorphism and granite generation. However, the heat sources needed for partial melting of the source rocks remain controversial. Lack of evidence for significant intrusion of mafic magmas necessary to cause melting of upper plate source rocks suggests that leucogranite generation in collisional orogens is mainly a crustal process.The present authors evaluate five types of thermal models which have previously been proposed for generating leucogranites in collisional orogens. The first, a thickened crust with exponentially decaying distribution of heat-producing radioactive isotopes with depth, has been shown to be insufficient for heating the upper crust to melting conditions. Four other models capable of raising the crustal temperatures sufficiently to initiate partial melting of metapelites in thickened crust include: (1) thick sequences of sedimentary rocks with high amounts of internal radioactive heat production; (2) decompression melting; (3) thinning of mantle lithosphere; and (4) shear-heating. The authors show that, for reasonable boundary conditions, shear-heating along crustal-scale shear zones is the most viable process to induce melting in upper plates of collisional orogens where pelitic source lithologies are usually located. The shear-heating model directly links partial melting to the deformation and metamorphism that typically precede leucogranite genera

Microlithic occurrences associated with sediments dated to terminal Pleistocene-late Holocene in the central Narmada basin, Madhya Pradesh, India

2021 ◽  
pp. SP515-2020-216
Author(s):  
Nupur Tiwari ◽  
P. Morthekai ◽  
K. Krishnan ◽  
Parth R. Chauhan
Keyword(s):  
Sri Lanka ◽  
South Asia ◽  
Late Pleistocene ◽  
Iron Age ◽  
Late Holocene ◽  
Indian Subcontinent ◽  
Central India ◽  
Madhya Pradesh ◽  
Doctoral Research ◽  
Terminal Pleistocene

AbstractThe earliest occurrence of microliths in South Asia dates back to the Late Pleistocene at Mehtakheri (45 ka) and Dhaba (48 ka) in Central India, Jwalapuram 9 in Southern India (38 ka), Kana and Mahadebbara in Northeastern India (42-25 ka) and Batadomba-Lena (35-36 ka) and Fa Hien Lena (48 ka) in Sri Lanka. Microlithic technology is distributed across the entire Indian Subcontinent and chronologically continues up to the Iron Age and Early Historic periods. This paper discusses new data acquired from the first author's doctoral research in the two districts of Madhya Pradesh (Hoshangabad and Sehore), which fall within the central part of the Narmada Basin in central India. We present here the preliminary dates from key areas of distribution to understand the geo-chronological contexts of microliths at Pilikarar, Morpani, and Gurla-Sukkarwada. Initial dates from these respective occurrences range between 12.5 ka and 2.3 ka.

Graphis and Allographa (lichenized Ascomycota: Graphidaceae) in Sri Lanka, with six new species and a biogeographical comparison investigating a potential signature of the ‘biotic ferry’ species interchange

2019 ◽  
Vol 51 (6) ◽  
pp. 515-559
Author(s):  
Gothamie WEERAKOON ◽  
André APTROOT ◽  
Robert LÜCKING ◽  
Omal ARACHCHIGE ◽  
Siril WIJESUNDARA
Keyword(s):  
New Species ◽  
Costa Rica ◽  
Sri Lanka ◽  
Species Composition ◽  
Alternative Explanation ◽  
Indian Subcontinent ◽  
Long Distance Dispersal ◽  
Long Distance ◽  
The North ◽  
First Time

AbstractWe provide an updated survey for Sri Lanka of species of Graphis sensu Staiger, recently divided into Graphis s. str. and Allographa, including brief descriptions and a key to all 124 species currently known. Six new species are described: Allographa bambusicola Weerakoon, Lücking & Aptroot, a bambusicolous Allographa with entire labia, a laterally carbonized excipulum, 80–100 × 15–17 µm large, muriform ascospores and a rather thick, irregularly verrucose lateral thalline margin of the lirellae; A. weerasooriyana Weerakoon, Arachchige & Lücking, a corticolous Allographa resembling A. rustica Kremp. in overall anatomy and chemistry, but with a verrucose thalline margin of the lirellae and labia not distinctly raised above the thalline margin; Graphis flosculifera Weerakoon, Lücking & Aptroot, a corticolous Graphis resembling G. insulana but differing in the unique disposition of the lirellae and the slightly more elongate ascospores; G. rajapakshana Weerakoon, Lücking & Aptroot, a corticolous Graphis resembling G. desquamescens, including in ascospore size, but with lirellae with a distinct lateral thalline margin; G. rimosothallina Weerakoon, Lücking & Aptroot, a corticolous Graphis with a thick, uneven, rimose thallus and Fissurina-like lirellae, a completely carbonized excipulum and transversely 7-septate ascospores, 32–37 × 8–10 µm; and G. thunsinhalayensis Weerakoon, Arachchige & Lücking, a corticolous Graphis resembling G. subalbostriata but with smaller ascospores and lacking white lines between the striae of the labia. We also validate the name G. verrucoserpens Lücking. A total of 106 species are reported here for the first time from Sri Lanka. A biogeographical comparison with two other well-sampled countries (Costa Rica and Thailand) revealed a significantly higher similarity in species composition with Costa Rica than between Thailand and Costa Rica, suggesting a potential signature of the ‘biotic ferry’ hypothesis, that is the migration of lineages from Gondwana (partly corresponding to the modern Neotropics) via the north-eastwards drifting Indian subcontinent and subsequent interchange with Laurasia (partly corresponding to the modern eastern Paleotropics). However, the evolutionary timeline of the clades involved does not support this hypothesis and suggests an alternative explanation of geologically more recent mid- to long-distance dispersal.

Control of Precambrian-to-Paleozoic orogenic trends on along-strike variations in Early Cretaceous continental rifts of the South Atlantic Ocean

2019 ◽  
Vol 7 (4) ◽  
pp. SH45-SH69 ◽  
Author(s):  
Kyle Reuber ◽  
Paul Mann
Keyword(s):  
Early Cretaceous ◽  
South Atlantic ◽  
Orogenic Belt ◽  
Deep Penetration ◽  
The South ◽  
The North ◽  
Continental Rifts ◽  
Rift Zones ◽  
Seismic Reflection Profiles ◽  
Orogenic Belts

The Early Cretaceous (135–130 Ma) continental rupture of Western Gondwana to form the South American and African plates closely paralleled the elongate trends of Precambrian and Paleozoic orogenic belts. These orogenic belts were produced as a result of the Neoproterozoic convergent and strike-slip assembly of Gondwana that redeformed during later, Paleozoic orogenic events. Continued continental rifting led to the formation of conjugate, South Atlantic volcanic passive margins whose widths vary from 55 to 180 km. Along-strike variations in crustal stretching, as measured from deep-penetration seismic reflection profiles, correlate with parallel and oblique orientations of rifts relative to the trend of the orogenic, basement fabric. Where orogenic fabric trends parallel to the north–south South Atlantic rift direction such as in the Dom Feliciano orogenic belt of Uruguay and Brazil and the Kaoko Uruguay/Brazil and Kaoko orogenic belt of Namibia, we observe narrow (55–90 km) rift zones with modest continental beta factors of 2.5–3.5 because smaller amounts of rifting were needed to stretch the weaker and parallel, orogenic, basement fabric. Where the basement fabric trends near-orthogonally to the north–south South Atlantic rift direction such as in the Salado suture of Southern Uruguay and the Damara Belt of Namibia, we observe wider (185–220 km) rift zones with higher beta factors of 4.3–5 because greater amounts of stretching were needed to rupture the orthogonal, orogenic, basement fabric. The rift-oblique Gariep Belt intersects the South Atlantic continental rupture at an intermediate angle (30°) and exhibits a predicted intermediate beta factor of 4.0. A compilation of published beta factors from 36 other rifted margins worldwide supports the same basement-trend-degree of stretching relationship that we have developed — with rift-parallel margins having lower beta factors in a range of 1.3–3.5 and rift-orthogonal or oblique margins having higher beta factors in a range of 4–8.

Petrogenesis of leucogranites in collisional orogens

2019 ◽  
Vol 491 (1) ◽  
pp. 179-207 ◽  
Author(s):  
Peter I. Nabelek
Keyword(s):  
Source Rocks ◽  
Crustal Thickening ◽  
Heat Sources ◽  
Active Deformation ◽  
Radiogenic Heat ◽  
Source Regions ◽  
Low Concentrations ◽  
Shear Heating ◽  
Orogenic Belts ◽  
Collisional Orogens

AbstractLeucogranites are a characteristic feature of collisional orogens. Their generation is intimately related to crustal thickening and the active deformation and metamorphism of metapelites. Data from Proterozoic to present day orogenic belts show that collisional leucogranites (CLGs) are peraluminous, with muscovite, biotite and tourmaline as characteristic minerals. Isotopic ratios uniquely identify the metapelitic sequences in which CLGs occur as sources. Organic material in pelitic sources results in fO2 in CLGs that is usually below the fayalite–magnetite–quartz buffer. Most CLGs form under vapour-poor conditions with melting involving a peritectic breakdown of muscovite. The low concentrations of Mg, Fe and Ti that characterize CLGs are largely related to biotite–melt equilibria in the source rocks. Concentrations of Zr, Th and rare earth elements are lower than expected from zircon and monazite saturation models because these minerals often remain enclosed in residual biotite during melting. Melting involving muscovite may limit the temperatures achieved in the source regions. A lack of nearby mantle heat sources in thick collisional orogens has led to thermal models for the generation of CLGs that involve flux melting, or large amounts of radiogenic heat generation, or decompression melting or shear heating, the last one emphasizing the link of leucogranites and their sources to crustal-scale shear zone systems.

Part IV Indian Subcontinent, 22 Sri Lanka

2011 ◽  
Author(s):  
Illukpitiya Dharshanie ◽  
Rodrigo Avindra
Keyword(s):  
Sri Lanka ◽  
Indian Subcontinent

Seven new species of the leafhopper genus Tambocerus (Hemiptera: Cicadellidae) from the Indian subcontinent

Zootaxa ◽  
2012 ◽  
Vol 3385 (1) ◽  
pp. 43 ◽  
Author(s):  
C. A. VIRAKTAMATH
Keyword(s):  
New Species ◽  
Sri Lanka ◽  
Tamil Nadu ◽  
Indian Subcontinent ◽  
Key To Species

Seven new species of the genus Tambocerus Zhang & Webb, Tambocerus acutus sp. nov., T. cholas sp. nov. (both from India:Tamil Nadu), T. daii sp. nov. (India: Kerala), T. furcostylus sp. nov. (India: Karnataka, Tamil Nadu), T. krameri sp. nov. (India,Karnataka; Sri Lanka), T. nilgiris sp. nov. (India: Tamil Nadu) and T. zahniseri sp. nov (India: Karnataka) are described andillustrated. T. viraktamathi Rao is redescribed and illustrated. A key to species of Tambocerus from the Indian subcontinent is also given.

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