Site index model for Tecomella undulata (Sm.) Seem. (Bignoniaceae) plantations in a hot arid region of India     

V.P. Tewari  B. Singh 《Journal of Arid Environments》2009,73(4-5):590-593

Tecomella undulata is an important indigenous tree species found in the hot desert areas of Rajasthan State in India. Data from 22 sample plots were used to model the dominant height growth of T. undulata. Four algebraic difference form equations were compared to select the best model. Autocorrelation was modeled as a first-order autoregressive process. The models were evaluated based on qualitative and quantitative criteria. The Payandeh and Wang's model, which is a base-age invariant polymorphic equation derived as a constrained version of the Chapman–Richards function, produced the best results. With this model, site index can be explicitly determined through direct evaluation of the functions and there is no need for iterative numerical evaluation methods. The model is applicable regardless of the choice of rotation age. The Payandeh and Wang's model is recommended for site classification and dominant height prediction in T. undulata stands in the hot desert of Rajasthan State in India.  相似文献   

Sedimentary - Tectonic Status of Permian - Triassic Boundary (250 Ma) in Gondwana Stratigraphy of Peninsular India     

R.C. Tewari 《Gondwana Research》1999,2(2):185

The sedimentary-tectonic status of Permian-Triassic boundary is examined in Gondwana stratigraphy of Peninsular India based on lithofacies characters, palaeoslope, and depositional models. The Late Permians represent meandering streams which flowed from southeast to northwest, except in Damodar basin where palaeoslope was from east to west. In Satpura, and Pranhita-Godavari basins, the Early Triassics record braided stream facies models. The palaeoslope remains northwesterly during Early Triassic sedimentation.Integrated evidence suggests that the Permian-Triassic boundary in Peninsular Gondwana stratigraphy of India is marked by tectonic discordance, and uplifts in the provenance.  相似文献   

An anomalous high-velocity layer at shallow crustal depths in the Narmada zone, India   总被引：2，自引：0，他引：2  

Prakash Kumar  H. C. Tewari  & G. Khandekar 《Geophysical Journal International》2000,142(1):95-107

The Narmada zone in central India is a zone of weakness that separates the region of Vindhyan (Meso-Neoproterozoic) deposition to the north from Gondwana (Permo-Carboniferous–lower Cretaceous) deposits to the south. The reinterpretation of analogue seismic refraction data, acquired during the early 1980s, using 2-D ray-tracing techniques reveals a basement (velocity 5.8–6.0 km s⁻¹ ) topography suggesting that the Narmada zone, bounded by the Narmada North and Narmada South faults is a region of basement uplift. A layer of anomalously high velocity (6.5–6.7 km s⁻¹ ) at depths between 1.5 and 9.0 km appears to be present in the entire region. Within the Narmada zone this layer occurs at shallower depths than outside the Narmada zone. At two places within the Narmada zone this layer is at a depth of about 1.5 km. This layer cannot be considered as the top of the lower crust because in this case it should have produced large positive gravity anomalies at the shallowest parts. Instead, these parts correspond to Bouguer gravity lows. Furthermore, lower crust at such shallow depths has not been reported from any other part of the Indian shield. Therefore, this layer is likely to represent the top of a high-velocity mafic body that has different thicknesses in different places.  相似文献   

Flux monitoring at 327 MHz during SL9-Jupiter collision     

Rakesh K. Malik  Pradeep Gothoskar  P. K. Manohran  G. Swarup  K. Subramanian  V. Balasubramanian 《Journal of Astrophysics and Astronomy》1995,16(3-4):393-398

Jupiter flux at 327 MHz was monitored using the Ooty radio telescope from July 12th to July 29th during the collision of comet Shoemaker-Levi 9 with Jupiter. Flux was found to increase steadily from July 17th to July 26th by ∼ 2–5 Jy, after which it declined to its pre-event value. The comparison of 327 MHz observations with those at 840 MHz and 2240 MHz indicates that the enhancement was mainly due to the increased synchrotron emission and the contribution of thermal emission was very small at metric-decimetric frequencies. The enhancement in radio emission was found to be more at 840 MHz than at 327 or 2240 MHz. The steepening of the spectrum between 327 and 840 MHz as well as between 2240 and 840 MHz was also noted.  相似文献   

Reply to the 'Comment Concerning: A Method of Obtaining A Velocity-Depth Envelope From Wide-Angle Seismic Data' By J. A. Orcutt, R. L. Parker, P. B. Stark, and J. D. Garmany     

Rakesh Mithal  John B. Diebold 《Geophysical Journal International》1988,95(1):211-212

  相似文献   

Crustal velocity inhomogeneities along the Hirapur–Mandla profile, central India and its tectonic implications     

A.S.N. Murty  Kalachand Sain  H.C. Tewari  B. Rajendra Prasad   《Journal of Asian Earth Sciences》2008,31(4-6):533-545

Wide-angle seismic and gravity data across the Narmada-Son lineament (NSL) in central India are analyzed to determine crustal structure, velocity inhomogeneities and hence constrain the tectonics of the lineament. We present the 2-D crustal velocity structure from deep wide-angle reflection data by using a ray-trace inverse approach. The main result of the study is the delineation of fault-bounded horst raised to a subsurface depth (1.5 km) and the Moho upwarp beneath the NSL. The crust below the basement consists of three layers with velocities of 6.45–6.7, 6.2–6.5 and 6.7–6.95 km/s and interface depths of about 5.5–8.7, 14–17 and 18–23 km along the profile. The low-velocity (6.2–6.5 km/s) layer goes up to a depth of 5 km and becomes the thickest part (13 km), while the overlying high-velocity (6.45–6.7 km/s) layer becomes the thinnest (3 km) and upper boundary lies at a depth of 1.5 km beneath the NSL. The overall uncertainties of various velocity and boundary nodes are of the order of ±0.12 km/s and ±1.40 km, respectively. The up-lifted crustal block and the up-warping Moho beneath the NSL indicate that the north and south faults bounding the NSL are deeply penetrated through which mafic materials from upper mantle have been intruded into the upper crust. Gravity modeling was also undertaken to assess the seismically derived crustal features and to fill the seismic data gap. The lateral and vertical heterogeneous nature of the structure and velocity inhomogeneities in the crust cause instability to the crustal blocks and played an important role in reactivation of the Narmada south fault during the 1997 Jabalpur earthquake.  相似文献   

Inelastic seismic response of one-storey,asymmetric-plan systems: Effects of system parameters and yielding     

Rakesh K. Goel  Anil K. Chopra 《地震工程与结构动力学》1991,20(3):201-222

The inelastic response of one-storey, asymmetric-plan systems to two excitations is presented and analysed with the objective of identifying the influence of system parameters: uncoupled lateral vibration period, uncoupled torsional-to-lateral frequency ratio, stiffness eccentricity, relative values of the strength and stiffness eccentricities, and yield factor. Furthermore, the influence of yielding on the response of asymmetric-plan systems is examined. In particular, we determine whether the well known relationship between the response of yielding and elastic single-degree-of-freedom (SDF) systems is also applicable to asymmetric-plan systems.  相似文献   

<Emphasis Type="Italic">Holigarna</Emphasis> (Anacardiaceae) from the early Eocene of Western India and its palaeogeographical and palaeoclimatological significance     

Anumeha Shukla  Rakesh Chandra Mehrotra 《Journal of the Geological Society of India》2016,87(5):520-524

Thick lignite deposits on the western margin of India were preserved on account of thick vegetation which got buried underneath due to tectonic activities that occurred in northwestern part of India during the early Palaeogene. Study of the fossil flora preserved in these beds is important to deduce the palaeoclimate of the region. Therefore, a field work was undertaken to collect plant fossils from the Tarkeshwar lignite mine, Surat district, Gujarat (western India) which is still unexplored as far as the plant mega-remains are concerned. A fossil wood is systematically described from the Cambay Shale Formation of the mine considered to be of early Eocene in age. It shows close affinities with Holigarna (Anacardiaceae), particularly with H. beddomei and H. grahamii. This genus is evergreen in nature and grows in the Indo-Malayan region, while both the modern analogues of the fossil are endemic to semi-evergreen to evergreen forests ofWestern Ghats, south India, located at the equator. This not only confirms the palaeolatitudinal position of the Indian subcontinent at the equator during the early Palaeogene, but also indicates the presence of equatorial rain forest in the Indian subcontinent during the period. Based on the timetree, Sapindales started to diverge in the early Palaeocene (62–57 Ma) as its oldest fossil is from the K-Pg boundary. Discovery of the present anacardiaceous fossil (belonging to Sapindales) from the early Eocene strengthens the above phylogenetic view.  相似文献   

Impact of landslide size and settings on landslide scaling relationship: a study from the Himalayan regions of India     

Jain  Saloni  Khosa  Rakesh  Gosain  A. K. 《Landslides》2022,19(2):373-385

Landslides - The reliable landslide hazard assessment entails a robust understanding of frequency-magnitude analysis of the landslide inventory. Previous studies proposed that the landslide...  相似文献   

Bathymetric significance of the ichnofossil assemblages of the Kulakkalnattam sandstone, Ariyalur area, Cauvery Basin     

R. Nagendra  Satish J. Patel  Rakesh Deepankar  A. N. Reddy 《Journal of the Geological Society of India》2010,76(5):525-532

Well preserved ichnofossils were found in Kulakkalnattam sandstone exposed at Kulakkalnattam stream in Ariyalur area, Cauvery Basin. It consists of infaunal structures of both suspension and deposit feeders. Five ichnofossils are present in a fine to coarse grain sandstone which includes Ophiomorpha, Palaeophycus, Planolites Skolithos, and Thalassinoides. The study infers that ichnofossils Skolithos and Ophiomorpha are infaunal colonization of the suspension feeders in high energy condition in shifting substrate, whereas Thalassinoides and Planolites-Palaeophycus ichnofossils indicate infaunal deposit feeders living at the sediment-sediment interface in low to moderate energy conditions. Furthermore, the abundance and diversity of the trace fossils indicates there was alternatively fluctuations in energy conditions which lead to development of Skolithos and Cruziana ichnofacies type condition during the deposition of Kulkkallanattam sandstone in foreshore-shoreface environments.  相似文献