Trace fossils from the late cretaceous Lameta Formation,Jabalpur area,Madhya Pradesh: Paleoenvironmental implications

In Jabalpur area about 18 m to 45 m thick Lameta Formation is stratigraphically divisible into five lithounits namely, Green Sandstone, Lower Limestone, Mottled Nodular Beds, Upper Limestone and Upper Sandstone. Having differentiated lithofacies constitution and here grouped as facies associations, these units are intensively burrowed and sparingly fossiliferous. Ichnogenera including Arenicolites, Calycraterion, Fucusopsis, Laevicyclus, Macanopsis, Ophiomorpha, Paleomeandron, Rhizocorallium, Stipsellus, Thalassinoides and Zoophycos are recovered from the Lower Limestone, Mottled Nodular Beds and Upper Limestone associations of the Lameta Formation of Jabalpur area.Among these, Arenicolites, Calycraterion, Laevicyclus, Ophiomorpha, Rhizocorallium, Stipsellus and Thalassinoides belong to mixed Skolithos and Cruziana ichnofacies and indicate sandy backshore to sublittoral condition of deposition. Additionally rhyzocretes, some times chertified, are also present in different parts of the Lameta Formation. Ichnofacies assemblage supported by sedimentological information suggests that the Lameta Formation of Jabalpur area was deposited in coastal marine settings where sediments were subaerially exposed intermittently.     

Non-cosmogenic lithium-6 in iron meteorites

A neutron activation method is used to measure⁶Li via the reaction⁶Li(n, α)³H in iron meteorites. It is found that most⁶Li occurs in non-metallic inclusions which can be separated by dissolution of the metal in 4 M H₂SO₄. The non-magnetic portion of such a residue has as high as 0.9 ppm⁶Li, while in the bulk sample⁶Li ranges from 0.02 to 10 ppb. Average⁶Li contents (ppb) for various classes are IA, 1.8; IIAB, 1.6; and IIIA, 0.4. Cosmic-ray-produced⁶Li is generally much smaller than the native⁶Li.     

Mapping runoff generating areas using AGNPS-VSA model

ABSTRACT

In humid regions, surface runoff is often generated by saturation-excess runoff mechanisms from relatively small variable source areas (VSAs). However, the majority of the current hydrologic models are based on infiltration-excess mechanisms. In this study, the AGricultural Non-Point Source Pollution (AGNPS) model was used to integrate the VSA concept using topographic wetness index (TWI). Both the original and AGNPS-VSA models were evaluated for a small agricultural field in Ontario, Canada. The results indicate that the AGNPS-VSA model performed better than original model. The AGNPS-VSA model predicted that only the saturated portion of the field with higher TWI values produced runoff, whereas the original AGNPS model showed uniform hydrologic response from the entire field. The results of this study are important for accurately mapping the locations of VSAs. This new model could be a powerful tool in identifying critical source areas for applying targeted best management practices to minimize pollutant loads to receiving waters.     

Toxicity and long term effects of a sublethal concentration of cadmium on the growth of the fingerlings of Ophiocephalus punctatus (BL.)

The LC₅₀ for exposure of 48 and 96 h is 34.64 and 18.5 mg/l Cd²⁺, respectively. During the exposure to 3.5 mg/l Cd²⁺ from the 13th day significant differences of length and mass occur with respect to the control. Over a total of 31 days of experiment the reduction of growth rates is 11% for the longitudinal growth and 16% for the increase in weight.     

General class of Bianchi cosmological models with Λ in creation-field cosmology

The solutions of Einstein’s equations with cosmological constant (Λ) in the presence of a creation field have been obtained for general class of anisotropic cosmological models. We have obtained the cosmological solutions for two different scenarios of average scale factor. In first case, we have discussed three different types of physically viable cosmological solutions of average scale factor for the general class of Bianchi cosmological models by using a special law for deceleration parameter which is linear in time with a negative slope. In second case, we have discussed another three different forms of cosmological solutions by using the average scale factor in three different scenarios like Intermediate scenario, Logamediate scenario and Emergent scenario. All physical parameters are calculated and discussed in each physical viable cosmological model. We examine the nature of creation field and cosmological constant is dominated the early Universe but they do not survive for long time and finally tends to zero for large cosmic time t. We have also discussed the all energy conditions in each cases.     

The response of the South Asian Summer Monsoon circulation to intensified irrigation in global climate model simulations

Agricultural intensification in South Asia has resulted in the expansion and intensification of surface irrigation over the twentieth century. The resulting changes to the surface energy balance could affect the temperature contrasts between the South Asian land surface and the equatorial Indian Ocean, potentially altering the South Asian Summer Monsoon (SASM) circulation. Prior studies have noted apparent declines in the monsoon intensity over the twentieth century and have focused on how altered surface energy balances impact the SASM rainfall distribution. Here, we use the coupled Goddard Institute for Space Studies ModelE-R general circulation model to investigate the impact of intensifying irrigation on the large-scale SASM circulation over the twentieth century, including how the effect of irrigation compares to the impact of increasing greenhouse gas (GHG) forcing. We force our simulations with time-varying, historical estimates of irrigation, both alone and with twentieth century GHGs and other forcings. In the irrigation only experiment, irrigation rates correlate strongly with lower and upper level temperature contrasts between the Indian sub-continent and the Indian Ocean (Pearson’s r = ?0.66 and r = ?0.46, respectively), important quantities that control the strength of the SASM circulation. When GHG forcing is included, these correlations strengthen: r = ?0.72 and r = ?0.47 for lower and upper level temperature contrasts, respectively. Under irrigated conditions, the mean SASM intensity in the model decreases only slightly and insignificantly. However, in the simulation with irrigation and GHG forcing, inter-annual variability of the SASM circulation decreases by ~40 %, consistent with trends in the reanalysis products. This suggests that the inclusion of irrigation may be necessary to accurately simulate the historical trends and variability of the SASM system over the last 50 years. These findings suggest that intensifying irrigation, in concert with increased GHG forcing, is capable of reducing the variability of the simulated SASM circulation and altering the regional moisture transport by limiting the surface warming and reducing land–sea temperature gradients.     

Parametric coupling between electromagnetic ion-cyclotron and shear Alfvén waves

The nonlinear interaction between finite amplitude electromagnetic ion-cyclotron waves and shear-Alfvén waves is considered. It is shown that this process is governed by three coupled equations. They are here used to study modulational instabilities. The relevance of our investigation to low-frequency electromagnetic fluctuations in space plasmas is pointed out.     

Solar and galactic cosmic‐ray records of the Fermo (H) chondrite regolith breccia

Abstract— ‐We demonstrate the presence of solar flare as well as neutron capture effects in the isotopic composition of rare gases in the Fermo regolith breccia acquired on its parent body based on the measurements of tracks, rare gases and radionuclides. The track density along a 3.2 cm long core decreases by a factor of about 6 and by more than a factor of 13 within the meteorite, indicating small (2–9 cm) and asymmetrical ablation. Rare gases show a large trapped component; the isotopic ratios, particularly ²⁰Ne/²²Ne ? 11 and ²⁰Ne/³⁶Ar = 10 are indicative of a solar component. The galactic cosmic‐ray exposure age is determined to be 8.8 Ma. Activities of a dozen radionuclides ranging in half‐life from 16 day ⁴⁸V to 0.73 Ma ²⁶Al are consistent with their expected production rates. Track, rare gas and radionuclide data show that the meteoroid was a small body (≤ 120 kg) and had a simple, one‐stage exposure history to cosmic rays in the interplanetary space. However, ⁸²Kr and ¹²⁸Xe show an excess due to neutron irradiation on the parent body of the meteorite. The presence of solar gases and the neutron capture effects indicate several stages of irradiation on the parent asteroid. The chemical composition of Fermo confirms that it belongs to the H group of ordinary chondrites with lithic clasts having varying compositions. δ¹⁵N is found to be 8.3 ± 1.2%0, close to the typical values observed in H chondrites.     

Coda Q in the Kachchh Basin, Western India Using Aftershocks of the Bhuj Earthquake of January 26, 2001

Q_C-estimates of Kachchh Basin in western India have been obtained in a high frequency range from 1.5 to 24.0 Hz using the aftershock data of Bhuj earthquake of January 26, 2001 recorded within an epicentral distance of 80 km. The decay of coda waves of 30 sec window from 186 seismograms has been analysed in four lapse time windows, adopting the single backscattering model. The study shows that Q_c is a function of frequency and increases as frequency increases. The frequency dependent Q_c relations obtained for four lapse-time windows are: Q_c=82 f^1.17 (20–50 sec), Q_c=106 f^1.11 (30–60 sec), Q_c=126f^1.03 (40–70 sec) and Q_c=122f^1.02 (50–80 sec). These empirical relations represent the average attenuation properties of a zone covering the surface area of about 11,000, 20,000, 28,000 and 38,000 square km and a depth extent of about 60, 80, 95, 110 km, respectively. With increasing window length, the degree of frequency dependence, n, decreases marginally from 1.17 to 1.02, whereas Q₀ increases significantly from 82 to 122. At lower frequencies up to 6 Hz, Q_c⁻¹ of Kachchh Basin is in agreement with other regions of the world, whereas at higher frequencies from 12 to 24 Hz it is found to be low.