EnVision: taking the pulse of our twin planet     

Richard C. Ghail  Colin Wilson  Marina Galand  David Hall  Chris Cochrane  Philippa Mason  Joern Helbert  Franck MontMessin  Sanjay Limaye  Manish Patel  Neil Bowles  Daphne Stam  Jan-Erik Wahlund  Fabio Rocca  David Waltham  Tamsin A. Mather  Juliet Biggs  Matthew Genge  Philippe Paillou  Karl Mitchell  Lionel Wilson  Upendra N. Singh 《Experimental Astronomy》2012,33(2-3):337-363

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Isolation of anaerobic,extremely thermophilic,sulphur metabolising archaebacteria from New Zealand hot springs     

B. K. C. Patel  P. M. Jasperse‐Herst  H. W. Morgan  R. M. Daniel 《新西兰海洋与淡水研究杂志》2013,47(3):439-445

Enrichments of New Zealand geo‐thermal samples, initiated in anaerobic sulphur‐containing media and incubated at temperatures above 85°C, yielded rod and coccal shaped organisms which possessed archaebacterial characteristics. Pure cultures were isolated and characterised. Five of the seven isolates, which were rod‐shaped organisms and did not have an obligate requirement for sulphur respiration, were similar to Thermoproteus sp. but had more neutral pH optima for growth. Three of these five Thermoproteus sp. were obligate heterotrophs, which has not previously been reported. The two coccal isolates had an obligate requirement for sulphur as an electron acceptor and were similar to Desulfurococcus sp. but again with more neutral pH optima for growth.  相似文献   

Burrowing activities of goby fish in the recent intertidal mud flats along the Navinal coast,Kachchh, Western India     

Nishith Y. Bhatt  Satish J. Patel  Dipal A. Patel  Hardik P. Patel 《Journal of the Geological Society of India》2009,74(4):515-530

Behavioural activities of the goby fish-Periophthalmodon septemradiatus were observed in the intertidal zone around Navinal coast in the Gulf of Kachchh, western India. Intertidal zone is broad, and comprise of creeks, which are muddy and vegetated by mangrove on eastern side and ridge runnel systems on western side of the study area which are hospitable for the goby fish. Different types of biogenic activities are observed such as crawling, pellet making, grazing and burrowing. The crawling activity is part of movement of the goby fish from one burrow to another burrow and pellet making activity is part of burrow modification. The grazing activity is feeding on the surface mud after receding of tide and exposure of the tidal flat by left and right movement of the front part of the body. The most conspicuous activity is burrowing, they construct unlined, vertical to incline ‘I’, ‘J’ and ‘Y’ shaped branched, circular to oval burrows with varying diameter and depth. In the muddy sediments goby fish produced circular to oval rimmed muddy lumps as surfacial expression around the burrows and further produced funnel shape depression and downward extended cylindrical holes, while in the runnels burrows are usually small and simple. The trail is consisting of fin marking on either side of the tail marks (grooves) which are radiate around the burrows. Occasionally burrows are interconnected in more than one burrow system which is nested within single funnel structure on the surface. The burrow systems of the goby fish in the intertidal sediments serves for protection and dwelling purpose and most importantly these burrows are irrigated by water which supply the oxygen and keep body surface wet. The overall dimensions of the burrow decrease towards the lower intertidal zone. In all, behavioural structure produced by the goby fish marks the combined activity of dwelling, feeding and grazing. The complex behavioural mechanisms have helped the goby fish to survive and flourish in the harsh intertidal environments along the Navinal Coast, in the Gulf of Kachchh.  相似文献   

Paleoecological significance of the trace fossils of Dhosa Oolite Member (Jumara Formation), Jhura dome,Mainland Kachchh,Western India     

S. J. Patel  B. G. Desai  R. Shukla 《Journal of the Geological Society of India》2009,74(5):601-614

Dhosa Oolite Member of the Jumara Formation comprises alternating bands of oolitic limestones and shales, exposed in Jhura dome of Mainland Kachchh, Western India. This sequence is highly bioturbated and exhibits a moderate diversity and behaviourally complex assemblage of ichnospecies. The rhythmically bedded sequence shows three different levels of preservation of traces. Epichnial tiering consists of moderately bioturbated oolitic limestone exhibiting horizontal or low-angle protrusive/retrusive biogenic laminae, commonly dominated by feeding structures like Rhizocorallium jenense, R. irregulare, Zoophycos brianteus and Zoophycos isp. The endichnial structures within the oolitic limestone can be separated into two different preservational trace fossil suites. The endichnial shallow suites consist chiefly of deposit feeders like Chondrites intricatus, C. targionii, Planolites beverleyensis, Taenidium cameronensis, Thalassinoides isp., Z. brianteus, Z. cf circinnatus and Zoophycos isp. and few suspension feeder forms like Palaeophycus tubularis; while endichnial deep suites consist of Chondrites intricatus, Skolithos linearis and Zoophycos isp. Hypichnial structures consists abundant, cylindrical, branched, horizontal, large-sized three dimensional feeding burrows of Thalassinoides isp. and somewhat irregular, obtuse angle ramification burrows of Phycodes isp., which are attached to the lower surface of the casting medium. The trace fossil association indicates Cruziana ichnofacies and abundance of Zoophycus species below the fair weather wave base level is largely a preservational artifact. The preservational processes of the trace fossils indicate soft substrate and diversity and their abundance reflects the other palaeoecological parameters of the open shallow marine environments.  相似文献   

Mafic xenoliths in Proterozoic kimberlites from Eastern Dharwar Craton,India: Mineralogy and P–T regime     

S.C. Patel  S. Ravi  Y. Anilkumar  A. Naik  S.S. Thakur  J.K. Pati  S.S. Nayak 《Journal of Asian Earth Sciences》2009,34(3):336-346

Mafic xenoliths of garnet pyroxenite and eclogite from the Wajrakarur, Narayanpet and Raichur kimberlite fields in the Archaean Eastern Dharwar Craton (EDC) of southern India have been studied. The composition of clinopyroxene shows transition from omphacite (3–6 wt% Na₂O) in eclogites to Ca pyroxene (<3 wt% Na₂O) in garnet pyroxenites. Some of the xenoliths have additional phases such as kyanite, enstatite, chromian spinel or rutile as discrete grains. Clinopyroxene in a rutile eclogite has an X_Mg value of 0.70, which is unusually low compared to the X_Mg range of 0.91–0.97 for all other samples. Garnet in the rutile eclogite is also highly iron-rich with an end member composition of Prp_26.5Alm_52.5Grs_14.7Adr_5.1TiAdr_0.3Sps_1.0Uv_0.1. Garnets in several xenoliths are Cr-rich with up to 8 mol% knorringite component. Geothermobarometric calculations in Cr-rich xenoliths yield different P–T ranges for eclogites and garnet pyroxenites with average P–T conditions of 36 kbar and 1080 °C, and 27 kbar and 830 °C, respectively. The calculated P–T ranges approximate to a 45 mW m^?2 model geotherm, which is on the higher side of the typical range of xenolith/xenocryst geotherms (35–45 mW m^?2) for several Archaean cratons in the world. This indicates that the EDC was hotter than many other shield regions of the world in the mid-Proterozoic period when kimberlites intruded the craton. Textural and mineral chemical characteristics of the mafic xenoliths favour a magmatic cumulate process for their origin as opposed to subducted and metamorphosed oceanic crust.  相似文献   

Geology of the Elephanta Island fault zone,western Indian rifted margin,and its significance for understanding the Panvel flexure     

Hrishikesh Samant  Ashwin Pundalik  Joseph D’souza  Hetu Sheth  Keegan Carmo Lobo  Kyle D’souza  Vanit Patel 《Journal of Earth System Science》2017,126(1):9

The Panvel flexure is a 150-km long tectonic structure, comprising prominently seaward-dipping Deccan flood basalts, on the western Indian rifted margin. Given the active tectonic faulting beneath the Panvel flexure zone inferred from microseismicity, better structural understanding of the region is needed. The geology of Elephanta Island in the Mumbai harbour, famous for the ca. mid-6th century A.D. Hindu rock-cut caves in Deccan basalt (a UNESCO World Heritage site) is poorly known. We describe a previously unreported but well-exposed fault zone on Elephanta Island, consisting of two large faults dipping steeply east–southeast and producing easterly downthrows. Well-developed slickensides and structural measurements indicate oblique slip on both faults. The Elephanta Island fault zone may be the northern extension of the Alibag–Uran fault zone previously described. This and two other known regional faults (Nhava–Sheva and Belpada faults) indicate a progressively eastward step-faulted structure of the Panvel flexure, with the important result that the individual movements were not simply downdip but also oblique-slip and locally even rotational (as at Uran). An interesting problem is the normal faulting, block tectonics and rifting of this region of the crust for which seismological data indicate a normal thickness (up to 41.3 km). A model of asymmetric rifting by simple shear may explain this observation and the consistently landward dips of the rifted margin faults.  相似文献   

Urban land use mapping: A case study of ahmedabad city and its environs     

SK Pathan  VK Shukla  RG Patel  BR Patel  KS Mehta 《Journal of the Indian Society of Remote Sensing》1991,19(2):95-112

Proper urban planning and effective implementation requires reliable urban land use statistics. In this context, satellite remote sensing data has been studied using both visual and digital techniques. A portable eight-band radiometer has been used to collect spectral signatures of surface features present in Ahmedabad city and its environs. Using these signatures a suitable approach employing visual and digital techniques has been developed for urban land use/sprawl mapping. Urban land-use maps of Ahmedabad city and its environs were prepared on 1:25,000 scale and for Ahmedabad Urban Development Authority Area on 1:50,000 scale using this methodology. It has been found that edge-enhancement techniques are useful to enhance the contrast among different urban land uses. Classification techniques such as MXL and Bayes classifiers are not successful in discriminating urban land uses. Tonal characteristics alongwith other elements of interpretation are required to classify urban land uses such as residential, industrial etc. Spatial distribution of various urban and uses and the space devoted to each urban land use has been brought out.  相似文献   

A computer simulation approach to modelling the structure,thermodynamics and oxygen isotope equilibria of silicates   总被引：1，自引：0，他引：1  

Atul Patel  Geoffrey D. Price  Monica J. Mendelssohn 《Physics and Chemistry of Minerals》1991,17(8):690-699

We use an atomistic model to simulate the structure, lattice dynamics and thermodynamics of silicate minerals. Our approach uses the Born model of a solid, in which the interaction between atoms is described by an interatomic pair potential. We have extended the study of thermodynamics to its very limit by looking at the subtle reaction of oxygen isotope exchange. We have modelled equilibria involving the important metamorphic minerals; albite, diopside, forsterite, pyrope, quartz and wollastonite. The predicted structural and thermodynamic data for these silicates are in very good agreement with the observed values. In addition, we predict not only the correct direction for the phase equilibria for oxygen isotope exchange, but also fractionation factors for the reaction to within a factor of two of the available experimental data. Hence, the potentials used in our approach have shown excellent transferability and have performed very well against the most stringent of tests.  相似文献   

District-level rice-yield estimation for Orissa using satellite data     

N Ravi  N K Patel  R R Navalgund  S Panigrahy  R N Dash 《Journal of the Indian Society of Remote Sensing》1992,20(1):43-49

Remotely-sensed data transformed into a vegetation index (radiance ratio of near infrared to red) has been related to district rice yields for Orissa using IRS-1A LISS-I data of kharif seasons 1988–89 and 1989–90. Using the empirical relation of the first year, estimation of rice yield has been done for the 1989–90 kharif season. Deviations in the districts of coastal tract and central tableland ranged from 1.9 to 11.1 percent whereas deviations were larger in Eastern Ghat and Northern plateau of Orissa.  相似文献   

Rb-Sr age of Godhra and related granites,Gujarat, India     

K Gopalan  J R Trivedi  S S Merh  P P Patel  S G Patel 《Journal of Earth System Science》1979,88(1):7-17

Rubidium and strontium determinations are reported for Godhra and geographically related granites from central Gujarat. The whole rock data define a Rb-Sr isochron corresponding to a common age of 955±20 m.y. and initial Sr ratio of 0·7130±0·001. This age is distinctly older than the age of 735 m.y. reported for the Erinpura suite of rocks from Mount Abu in western Rajasthan and from Idar in northern Gujarat. There are at least two generations of post-Delhi intrusive rocks in the Gujarat precambrian. Biotites associated with these granites have the same age as the whole-rocks within experimental error indicating the absence of significant metamorphic heating since the time of emplacement. It is significant that rocks of similar age occur in the Rajasthan Precambrian mainly in the axial zone of the Aravalli Mountains.  相似文献