Period variations in SZ Arietis

A new period (P=1^d.7175405) of the eclipsing binary system SZ Arietis has been presented. Period changes in different portions of the O-C diagram, with new period, have been estimated. The total change in period (P) ranges from 3.64×10^–5 d to 4.24×10^–4 d, which is appreciably large. However, leaving the unusual value, the average period change comes out to be of the order of 6×10^–5 d. The period changes around the years 1903, 1943, and 1977 are apparent in the O-C diagrams. A sinusoidal variation is also visible in the O-C diagrams which indicates that SZ Ari may be a three-body system, having a period of nearly 66 years.     

ST Persei: A possible multi-body system

Detailed period study of the eclipsing binary ST Per is presented. A new period (P=2^d.648339) is given. Period changes in different portions of the O-C diagram with a new period have been estimated. The total changes in period (P) ranges from 2.17×10^–5d to 2.64×10^–4d which is appreciably large. Sufficient number of minima in the time interval 1934 to 1985 for this system are available. Distinct increasing and decreasing trends are evident, the change in the tendency appears to have occurred around 1947. Sinusoidal variation is seen between cycles 7000–10000, which indicates that ST Per is a three-body system, the period of the third body being about 22 years. However, the sinusoidal variation is not perfectly symmetric in shape, therefore, it is suspected that ST Per is a four-(or multi-) body system.     

Variations in vapor pressure and standardized precipitation evapotranspiration index since AD 1861 over the western Himalaya in India: inference from tree ring-width records

A regional tree ring-width index chronology prepared from various tree core samples of the western Himalaya has been analyzed in relation to climate fluctuations. The correlation analysis of tree ring chronology shows significant positive correlations with regional rainfall and standardized precipitation evapotranspiration index (SPEI) and negative correlations with temperature and vapor pressure (VP) during the spring season. The correlation coefficients (CCs) of tree ring-width index chronology with rainfall, temperature, SPEI, and VP during 1901–1990 are 0.50, −0.49, 0.65, and −0.51, respectively. All CCs are significant at 0.1% level. The highly significant CCs between tree ring-width index chronology and SPEI indicate that tree growth over the western Himalaya is more sensitive to soil moisture availability than rainfall, whereas the rising VP is found to have a significant moisture stress condition to tree growth by accelerating the evapotranspiration, which is not conducive for the development of tree growth in the region. So, based on the strong association between tree ring-width index chronology and SPEI; the reconstructions of SPEI and VP are developed back to AD 1861, that show the long period of dryness during 1936–1963.     

Plane-symmetric universes in general relativity

Plane-symmetric solutions of Einstein's field equations in vacuum, in the presence of electromagnetic fields and with cosmological constant are explored in null coordinates. The gravitational field of an infinite plane (uncharged and charged both) is thus obtained in a simple and systematic way. The method adopted for these solutions has possibilities of generalization.     

1891–1883 Ma Southern Bastar–Cuddapah mafic igneous events, India: A newly recognized large igneous province

A newly recognized remnant of a Paleoproterozoic Large Igneous Province has been identified in the southern Bastar craton and nearby Cuddapah basin from the adjacent Dharwar craton, India. High precision U–Pb dates of 1891.1 ± 0.9 Ma (baddeleyite) and 1883.0 ± 1.4 Ma (baddeleyite and zircon) for two SE-trending mafic dykes from the BD2 dyke swarm, southern Bastar craton, and 1885.4 ± 3.1 Ma (baddeleyite) for a mafic sill from the Cuddapah basin, indicate the existence of 1891–1883 Ma mafic magmatism that spans an area of at least 90,000 km² in the south Indian shield.This record of 1.9 Ga mafic/ultramafic magmatism associated with concomitant intracontinental rifting and basin development preserved along much of the south-eastern margin of the south Indian shield is a widespread geologic phenomenon on Earth. Similar periods of intraplate mafic/ultramafic magmatism occur along the margin of the Superior craton in North America (1.88 Ga Molson large igneous province) and in southern Africa along the northern margin of the Kaapvaal craton (1.88–1.87 Ga dolerite sills intruding the Waterberg Group). Existing paleomagnetic data for the Molson and Waterberg 1.88 Ga large igneous provinces indicate that the Superior and Kalahari cratons were at similar paleolatitudes at 1.88 Ga but a paleocontinental reconstruction at this time involving these cratons is impeded by the lack of a robust geological pin such as a Limpopo-like 2.0 Ga deformation zone in the Superior Province. The widespread occurrence of 1.88 Ga intraplate and plate margin mafic magmatism and basin development in numerous Archean cratons worldwide likely reflects a period of global-scale mantle upwelling or enhanced mantle plume activity at this time.     

Petrology, geochemistry and genesis of rift-related carbonatites of Ambadungar, India

Summary The Ambadungar (Amba Dongar) alkaline carbonatite complex is emplaced in the Deccan traps igneous province. A wide range of carbonatites and alkaline rocks are exposed around Ambadungar. The alkaline rocks have been classified as tinguaite, phonolite and/or phononephelinite, melanephelinite, and syenite and/or nepheline syenite whereas carbonatites vary from calcio-carbonatites to ferro- and silicocarbonatites. The enrichment in large-ion lithophile elements (LILE), P, and rare-earth elements (REE) in carbonatites is considered to result from fractionation of a mantle derived magmatic liquid, i.e. nephelinitic magma, by liquid immiscibility which also produced melanephelinite and/or phononephelinite with high field strength elements (HFSE) such as Ca, Mg, Fe, and Mn in the alkaline silicate liquid fraction. The La:Lu ratios of the carbonatites are typical of igneous rocks and vary between 590 and 1945, similar to many known magmatic carbonatites. The ¹³C concentration varies between –2 and –8 whereas ¹⁸O-values vary between 7.7 and 26.8. The ¹³C concentration is typical of primary igneous carbonatites but ¹⁸O enrichment is thought to be the result of post-magmatic processes such as interaction with meteoric water and re-equilibration with hydrous fluids at low temperatures.

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Petrologie, Geochemie und Genese der riftgebundenen Karbonatite von Ambadungar, Indien

Zusammenfassung Der Ambadungar (Amba Dongar) Alkalikarbonatit-Komplex liegt in der magmatischen Deccan Provinz. Er umfaßt eine Vielzahl von karbonatitischen und alkalischen Gesteinen, die in der Umgebung von Ambadungar aufgeschlossen sind. Die Alkaligesteine sind als Tinguaite, Phonolite und/oder Phononephelinite, Melanephelinite, Syenite und/oder Nephelinsyenite zu klassifizieren, die Karbonatite als Calcio-, bis Ferro- and Silicokarbonatite. Die Anreicherung an LIL-Elementen und Seltenen Erden in den Karbonatiten werden als das Ergebnis der Fraktionierung von Mantelschmelzen, i.e. eines nephelinitisches Magmas, infolge von Nichtmischbarkeit interpretiert. Melanephelinite und/oder Phononephelinite and hohe Gehalte an HFS-Elementen (Ca, Mg, Fe and Mn) in der alkalisch-silikatischen Schmelzfraktion sind ebenfalls das Ergebnis dieser Prozesse. Die La/Lu-Verhältnisse sind typisch für magmatische Karbonatite and variieren zwischen 590 and 1945. Die ¹³C Konzentrationen variieren zwischen -2 and -8 %o, die ¹⁸O Werte zwischen 7.7 and 26.8 %0. Während die ¹³C Konzentration typisch für primär magmatische Karbonatite ist, ist die ¹⁸O-Anreicherung mit postmagmatischen Prozessen, wie etwa die Interaktion mit meteorischen Wässern and die Reequilibration mit niedrig temperierten wäßrigen Fluiden, erklärbar.

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with 11 figures     

Testing of coupled SCS curve number model for estimating runoff and sediment yield for eleven watersheds

The soil conservation service (SCS) methodology for computing direct run-off, using soil-cover-moisture complexes involves the selection of a runoff curve number (CN) for such complex events. This method has been further simplified by introducing an assumption on initial abstraction, with only one unknown parameter CN, which is represented by the potential retention capacity of the watershed (S). In this study, coupled SCN-CN with USLE model was used for the estimation of the runoff and sediment yield for eleven watersheds of different land uses (urban, agricultural, and forest) from Damodar Valley Corporation (DVC), Hazaribagh district, Jharkhand, India. For the validation, runoffsediment yield model is employed to a large set of rainfall-runoff-sediment yield data (68 storm events) observed from eleven watersheds. Model performance was assessed by using Nash and Sutcliffe statistical method. The efficiency of results was varying from 60.42 to 92.99 % for sediment yield and 54.23 to 96.12 % for runoff; this efficiency showed a reliable performance of model for estimating the sediment yield and runoff.     

Statistical parameters of Bhuj earthquake sequence of January 26th, 2001

An intraplate earthquake of magnitude (M _c) 6.9 (Anon 2001a) struck Bhuj and the adjoining region of Kachchh in Gujarat on January 26th, 2001 at about 0316 hrs (GMT) and was followed by a number of aftershocks. The epicentre of this earthquake was located at 23.4‡N and 70.28‡E close to the Kachchh mainland fault. The intensity observed around the epicenter was X on the MSK scale. A study of 531 aftershocks, in the magnitude range of 3.0–5.7, recorded at Vadodara Seismological Observatory till March 31st, 2001 has been carried out and various statistical parameters calculated. The total energy released during the study period is calculated to be 8.2 × 10¹⁴ joule. Sudden occurrence of the main shock without any foreshock in the same tectonic system is a unique feature of this sequence. Theb- value (0.86), value of M₀-M₁ (1.2), high M₁/M₀ (0.89) and high value of the decay constanth (0.91), all support the tectonic origin of the present study.     

Semi-empirical method for calculation of maximum subsidence in coal mines

Summary Most empirical methods of subsidence prediction are based on the prior knowledge of the maximum possible subsidence, S_max, for a particular coalfield. The subsidence profile and other associated parameters along a desired line may be derived, in most cases, as a function of S _max. These methods are site specific and are not based upon the rational concepts of mechanics. Purely mechanistic methods, on the other hand, could not find wide application because of their limitations in representing the complex behaviour of a rockmass.Therefore a semi-empirical method of calculation of S _max or S, which is an improvement over the empirical method reported elsewhere (Bahuguna et al., 1991a), has been derived from combining the mechanistic and empirical approach. The effects of various parameters are studied by numerical modelling. These qualitative results are then used to influence the development of a more general semiempirical method. The method has been tested for 125 coal mine workings in India and 22 mines of the North Appalachian basin. The method is easily adaptable to other countries.