Trace elemental and Nd-Sr-Pb isotopic compositional variation in 37 lava flows of the Mandla lobe and their chemical relation to the western Deccan stratigraphic succession,India     

J. P. Shrivastava  J. J. Mahoney  M. R. Kashyap 《Mineralogy and Petrology》2014,108(6):801-817

The Mandla lobe is a 900 m thick lava pile that forms a 29,400 km² northeastern extension of the Deccan Traps. Earlier, combined field, petrographic, and major element studies have shown that this lobe comprises 37 lava flows. Using a combination of trace elements (Ba, Ti, Zr, Rb, Sr) and Nb/Zr values, we group the flows into six chemical types (A–F) that are separated stratigraphically. Combined trace element and Nd-Pb-Sr isotopic data, document the presence of lavas resembling those of the Poladpur Formation and less abundantly, the Ambenali Formation of the southwestern Deccan are in conformity with the earlier reconnaissance work. In addition, our data reveal several flows similar to those of the Mahabaleshwar Formation, the type sections of which are located?~?900 km to the southwest. Based on the isotopic data the superposition of Mahabaleshwar-like flows over flows with Ambenali- and Poladpur-like characteristics is in the same stratigraphic order seen in the southwestern Deccan type section. However, from the stratigraphy indicated by the Discriminant Function Analysis (DFA) results and the serious discrepancy between the DFA and isotopic data, it seems that few Mandla lobe flows are different and not in the same stratigraphic order as in the southwestern part of the province. To some extent the differences may be explained by faulting along four large post-Deccan normal faults near Nagapahar, Kundam, Deori, and Dindori areas across which offsets of ~150 m have been measured. This post-emplacement faulting accounts for the presence of several chemically Mahabaleshwar-like lavas at the base of the ~900 m thick Mandla lobe pile, at a lower elevation than a thick sequence dominated by chemically Poladpur-like flows. However, presence of common signature lavas (similar to that in the northeastern Deccan) cannot be ruled out in this area. They are similar to Poladpur-type lavas both chemically and isotopically. They appear in different formations and erupted at different times other than Poladpur Formation. Close similarities in petrogenetic processes between the two regions are indicated, although it is not clear whether any of the Mandla lobe lavas are far-traveled counterparts of flows cropping out in the southwestern Deccan, or whether some magma migrated laterally in dike systems over great distances. Feeder dykes have not been found in the study area except for Chakhla-Delakhari Intrusive Complex (CDIC) in Satpura region that shows major and trace elemental similarities with the Seoni lavas, although, long distance transport of magma is yet to be proved. The Poladpur-like Mandla lobe flows appear to be different flows from those of the Poldapur Formation in the southwest, as they are somewhat different in isotopic (higher ²⁰⁶Pb/²⁰⁴Pb) composition. They also differ from any known flows in the other southwestern formations, but are broadly similar to flows found in sections across the northern Deccan west of the Mandla lobe.  相似文献   

Ionic characters of lake water of Bharti promontory,Larsemann Hills,East Antarctica     

Prakash K. Shrivastava  Rajesh Asthana  M. Javed Beg  Rasik Ravindra 《Journal of the Geological Society of India》2011,78(3):217-225

The Larsemann Hills area represents a unique environmental setting between marine and glacial ecosystems. One of the promontories of this region, named Bharti, depicting similar set up was selected for the study of chemical parameters with special reference to its ionic characters. Water samples from 6 selected lakes of Bharti promontory, Larsemann Hills area were collected during the austral summer of 2004–05 and analysed for major ionic concentration and Total Dissolved Solid (TDS). This study is aimed at understanding the water chemistry of lakes of this island with emphasis on correlation between different ionic concentrations, TDS and its possible causes. The study will provide baseline data that will be useful for planning further studies. Analytical result shows that the water chemistry of these lakes is mainly governed by the lithology, precipitation, drainage and marine environment. Minor contribution of evaporation, has also been observed on the chemistry of one of the lake water. The main source of water for these lakes comes mainly from snow precipitation and its melting. The drainage line mostly goes towards eastern direction for these lakes.  相似文献   

Trace elements geochemistry and petrogenesis of basalt from the southern part of the East Pacific Rise     

Sanjay Kumar Pandey  Sucharita Pal  J. P. Shrivastava  G. S. Roonwal 《Journal of the Geological Society of India》2013,81(1):91-100

Trace element geochemistry of basalt samples collected from 6°S-24°S of the southern EPR, representing a super-fast spreading axis is discussed. Trace element data classify these basalts into Normal and Transitional types of MORB, however, LREE enrichment is also observed in few of them. Chondrite normalized REE data plots show highly fractionated nature of these lavas, suggesting their derivation from the primitive mantle source. Petrogenetic modeling of the data suggests variation in the solidus pressure (14–20 kb.) and temperature (1316–1425°C), where 15 to 20% partial melting of the mantle is accountable for the generation of the melt. The pressure and temperature conditions at the beginning of the mantle melting were high along higher latitudes (24°S of EPR), but it gradually lowered down in the lower latitudinal areas (6°S of EPR), supporting for the presence of passively rising upper mantle beneath the Southern EPR.  相似文献   

Feeder and post Deccan Trap dyke activities in the northern slope of the Satpura Mountain: Evidence from new 40Ar-39Ar ages     

J.P. Shrivastava  R. Kumar  N. Rani 《地学前缘(英文版)》2017,8(3):483-492

We present new 40Ar-39 Ar plagioclase crystallization ages from the dykes exposed at the northern slope of the Satpura Mountain range near Betul-Jabalpur-Pachmarhi area,~800 km NE of the Western Ghats escarpment.Among the two plateau ages,the first age of 66.56±0.42 Ma from a dyke near Mohpani village represents its crystallization age which is either slightly older or contemporaneous with the nearby Mandla lava flows(63-65 Ma).We suggest that the Mohpani dyke might be one of the feeders for the surrounding lava flows as these lavas are significantly younger than the majority of the main Deccan lavas of the Western Ghats(66.38-65.54 Ma).The second age of 56.95±1.08 Ma comes from a younger dyke near Olini village which cuts across the lava flows of the area.The age correlates well with the Mandla lavas which are chemically similar to the uppermost Poladpur,Ambenali and Mahabaleshwar Formation lavas of SW Deccan.Our study shows that the dyke activities occurred in two phases,with the second one representing the terminal stage.  相似文献   

Effects of γ-Rays on Hatching' of the Eggs and Survival Period of Fries of Cyprinus carpio     

R. S. Shrivastava  P. Dwivedi 《洁净——土壤、空气、水》1980,8(4):311-317

The eggs of Cyprinus carpio were irradiated by 5 different strengths: 0.0258, 0.129, 0.258, 0.516 and 1.29 C/kg (100, 500, 1000, 2000 and 5000 R) of γ-rays in the batches of 50 fertilized eggs. The activities of eggs and hatched fries were noted after irradiation doses. The hatching percentages of the eggs were reported for each group. The percentage of hatched eggs of Cyprinus carpio after radiation doses of 0.0258, 0.129, 0.258, 0.516 and 1.29 C/kg (100, 500, 1000, 2000 and 5000 R) was 30%, 24%, 28%, 30%, and 34%, respectively. The 50% mortality period of fries for the above strengths of the γ-rays was 8 days, 7 days, 6 days. 4 days and 4 days, respectively. The survival period of the fries was 11 days, 9 days, 8 days, 7 days and 6 days, respectively. All fries hatched from the eggs irradiated by γ-rays showed early hatching, a higher percentage of mortality, a retarded and abnormal development of the body. A statistical analysis of the results by the correlation coefficient also proved that the hatching percentages of the fries and the survival period of fries are directly proportional to the strength of the γ-rays and inversely proportional to the strength of γ-rays, respectively.  相似文献   

Trace elemental signatures and mineral chemistry of clays associated with the alteration halos of the Paleoproterozoic U mineralization in Bijawars of the Sonrai Basin,Central India     

Jha  Surendra Kumar  Sharma  Rashmi  Shrivastava  Jaya Prakash 《中国地球化学学报》2020,39(3):365-386

Acta Geochimica - Paleoproterozoic Bijawars of the Sonrai basin consists of (a) Sonrai (mostly carbonate carbonaceous shale and phosphatic breccia) and (b) Solda Formations (commonly chloritic and...  相似文献   

Provenance and depositional environment of epi-shelf lake sediment from Schirmacher Oasis,East Antarctica,vis-à-vis scanning electron microscopy of quartz grain,size distribution and chemical parameters     

Prakash K. Shrivastava  Rajesh Asthana  Sandip K. Roy  Ashit K. Swain  Amit Dharwadkar 《Polar Science》2012,6(2):165-182

The scientific study of quartz grains is a powerful tool in deciphering the depositional environment and mode of transportation of sediments, and ultimately the origin and classification of sediments. Surface microfeatures, angularity, chemical features, and grain-size analysis of quartz grains, collectively reveal the sedimentary and physicochemical processes that acted on the grains during different stages of their geological history. Here, we apply scanning electron microscopic (SEM) analysis to evaluating the sedimentary provenance, modes of transport, weathering characteristics, alteration, and sedimentary environment of selected detrital quartz grains from the peripheral part of two epi-shelf lakes (ESL-1 and ESL-2) of the Schirmacher Oasis of East Antarctica. Our study reveals that different styles of physical weathering, erosive signatures, and chemical precipitation variably affected these quartz grains before final deposition as lake sediments. Statistical analysis (central tendencies, sorting, skewness, and kurtosis) indicates that these quartz-bearing sediments are poorly sorted glaciofluvial sediments. Saltation and suspension seem to have been the two dominant modes of transportation, and chemical analysis of these sediments indicates a gneissic provenance.  相似文献   

Average anisotropy characteristics of high energy cosmic ray particles and geomagnetic disturbance index Ap     

C. M. Tiwari  D. P. Tiwari  Ajay K. Pandey  Pankaj K. Shrivastava 《Journal of Astrophysics and Astronomy》2005,26(4):429-434

The average characteristics of the diurnal and semi-diurnal anisotropy of cosmic ray intensity at relativistic energies have been obtained by using data from the worldwide grid of neutron monitor for the period 1989 to 1996. The complex behaviour of the diurnal amplitudes and time of maxima (phase) and its association with the Ap index on a long-term and day-to-day basis have been studied. Even though the general characteristics, on a yearly average basis, have not changed significantly during this period, both the diurnal and semi-diurnal amplitudes and phases vary significantly, besides significant changes being observed for different interplanetary conditions on a short-term basis. It is found that the relationship between the Ap index and the diurnal vector is out of phase during the period 1991 to 1995. On a long-term basis, the correlation of diurnal variation with Ap index has been found to vary during the solar cycle. On a short-term basis, it has been observed that the high Ap days are usually associated with higher amplitudes with phase shifted to earlier hours.  相似文献   

High-Speed Solar wind Streams and Cosmic-Ray Intensity Variations During 1991–1996     

Shrivastava  Pankaj K.  Jaiswal  K.L. 《Solar physics》2003,214(1):195-200

High-speed plasma streams identified in the solar wind measurements can be separated into two categories: coronal-hole-associated streams and flare-generated streams. Effects of these plasma streams on cosmic-ray intensity are studied for the period of 1991–1996. It is investigated that both of these high-speed solar wind plasma streams (CS and FGS) are found equally effective in producing the cosmic-ray intensity decrease on short-term basis.  相似文献   

An Experimental Study of Compaction Grouting on Its Densification and Confining Effects     

Neha Shrivastava  Kouki Zen 《Geotechnical and Geological Engineering》2018,36(2):983-993

Compaction grouting (CPG) involves the injection of high viscosity mortar-type grout under relatively high pressure that displaces and compacts the soil in-place. Many case studies around the world prove the effectiveness of CPG to treat liquefiable soils. In these studies, mostly CPG has been developed and used on the basis of practical experiences, its densification and confining effects are not well understood until now. The objective of the present study is to bring out densification and confining effects of CPG. This paper presents a laboratory experimental study carried out to model a CPG treated ground. The study includes the experiments performed to decide appropriate consistency of grout material and appropriate relative contribution of factors such as overburden pressure, grout volume, injection speed and injection pressure that ensures efficient grouting. The effects of CPG are quantified in terms of lateral earth pressures and lateral displacements that are further defined in terms of coefficient of lateral earth pressure, K, and densification factor in the soil around grout column. This leads to a better understanding of its densification and confining effects. Although in practice, majority of the works with CPG have been related to its densification effect and lesser attention has been given to its confinement effect, in present experimental study, its confinement effect were prominent. Also at the farthest locations usually where field tests are carried out, its densification effect could not be found experimentally but its confinement effect was clear.  相似文献