006358   Rao K S;Rao A T;Rao K N (Geo Dep, Andhra Univ, Visakhapatnam-530 003) : Clay mineralogy of Penner deltaic sediments, east coast of India. Indian Mineralogist 2002, 36-37(2,1), 24-30.

The clay minerals identified in the Penner deltaic sediments are Kaolinite, illite and smectite. Kaolinite (<126>20-30%) is the abundant clay mineral and illite is in subordinate amount (<126>20-30%<126>60-70%<126>15-20%

1 illus, 2 tables, 25 ref

006357   Prasad B B;Gupta S;Banerjee S (Analytical Division, Dep of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi-221 005) : Voltammetric studies of an oxazolone derivative of cefaclor in aqueous buffers. Indian J Chem-Sect A 2002, 41(10), 2025-31.

Electrochemical properties of cefaclor at a mercury electrode in aqueous solution of varying pH have been studied through tast, pulse (normal and differential), and cyclic voltammetric techniques. For this, the electroinactive cefaclor is transformed into electroactive penicillenate analogue `oxaxolone derivative' under strong acidic hydrolysis condition. The derived oxazolone system underwent two-steps irreversible reductions involving proton-partions (2e^-, H⁺, 4e, 4H⁺) when voltammograms scanned cathodically. However, in cyclic voltammetry, atypical wave due to sulphhydryl group oxidation is noticed on scan reversal in anodic direction. The results have been discussed by taking into account the implication of reactant and production adsorptions onto electrode surface during the course of reductions.

4 illus, 1 table, 23 ref

006356   Patil R R;Patil K T (Geo Dep, Shivaji Univ, Kegaon, Solapur-413 002) : Environment of amygdular cuprite in basaltic flow from Ladole, Barshi taluka, Solapur district, Maharashtra. Indian Mineralogist 2002, 36-37(2,1), 76-84.

Deccan Tholeiitic Basalts with diverse compositions have been erupted in different geological periods. Among these tholeiities are known for their metallic enrichment and deserve attention for their ore potential. A locally occurring cuprite mineralization from Ladole is reported for the first time. Tholeiitic basaltic samples studied from Ladole indicated Cu-Pb-Zn-Ni in traces. Study indicates that geochemically and structurally controlled occurrence of cuprite mineralization is typically found associated with quartz along with zeolites and calcites as gangue. Cuprite shows coppery reddish color and is found in cubic habit. This mineral occurrence is altered to azurite and malachite towards the surface. At depth it shows signs of supergene sulphide enrichment where chalcopyrite, cubanite, bornite and diagenite show their predominance. The epigenetic nature of this mineralization is evident through structures, like filling of amyglades, veins, fractures, vesicles, shears and joints. Fluid inclusion studies carried out on transparent gangue and translucent cuprite revealed presence of four types of inclusion as liquid, saline, gaseous and super saline based on their contents at room temperature. The thermocryometric study on these inclusions indicate that mineral media had temperature more than 290°C and the cooling resulted in the deposition of cuprite with different assemblages

8 illus, 1 table, 15 ref

006355   Nagendra R;Nagarajan R (Centre for Geosci Engng, Anna University, Chennai-25) : Geochemical studies of Shahabad limestone (younger Proterozoic), Bhima basin, Karnataka. Indian Mineralogist 2002, 36-37(2,1), 13-23.

The Shahabad Formation (younger Proterozoic) of Bhima Group, consisting of carbonate rock is well developed in Gulbarga, Karnataka and Rangareddy district, Andhra Pradesh. The carbonates which are dominantly limestones, belonging to Shahabad Formations is black to dark-grey, greyish black, to purple, fine grained, massive, flaggy, blocky and slabby. The recrystallized microspar, rounded sparry calcite fillings, macro and microstylolite structures are common in the limestone. SEM photographs has been used to interpret the grain relationship and limestone fabric. XRD studies and staining of the limestone indicate the presence of quartz and calcite minerals. The Al₂O₃ variation in the limestone suggests that the influx of sediments is from terrigenous soures. The low MgO is attributed to extensive leaching of silica influx and diagenetic alterations. The low content of Sr is mainly due to removal by permeating freshwater during the diagenesis of these limestones. The micritic textures of Shahabad limestone indicate that it has formed as a result of degrading neormorphism subsequent to precipitation in low energy marine condition.

3 illus, 3 tables, 23 ref

006354   Misra A;Hukmani N S (Senior Project Coordination for Energy Studies and Res, Devi Ahilya Vishwavidyalaya, Indore) : Weather data and ambient design conditions for Indian stations (WeDCo database). SESI Jl 2002, 12(1), 25-35.

Ambient design conditions have been developed for 58 Indian stations by Tata Energy Research Institute (TERI), New Delhi, India, from the measured sequences of climatic data from 1981 to 1992. Synoptic-hours climatic data sets were procured from India Meteorological Department (IMD), decoded, analyzed and stored in a database. The analysis included averaging, interpolation, and determination of cumulative frequency distribution of temperatures. Fourier analysis was used to convert 3-hourly synoptic data to hourly data for all the stations. The results have been presented in the ASHRAE (1997) format as design temperatures (Dry-bulb and mean coincident Wet-bulb) at 0.4%, 1.0% and 2.0% annual frequencies of occurrence. In addition, reference weather years containing most probable hourly values of 14 climatic parameters have been developed for each of the stations. These parameters include total and diffuse solar radiation, which have been synthesized using the Meteorological Radiation Model, and validated against the measured radiation values supplied by IMD.

1 illus, 2 tables, 12 ref

006353   Maya Unde (Geography Dep, , Ahmednagar) : Physiographic characteristics of Ahmednagar plateau. Trans Inst Indian Geogr 2001, 23(1-2), 139-47.

The appraisal of land resources for any field of planning needs to take into account the landuse land cover condition of the region. This is basically for the reason that it facilitates the understanding of the pattern of utilisation of the land resources appraisal ralate to the physiographic and drainage characteristics of the region. The relief of the area determines the availability of land, of the land, while the soil in general influences the quality of the land, particularly when the land is being utilised for agrarian activity. With the availability of the remote sensing products in the form of digital data and satellite images the work of land resource appraisal has become relatively easy information, which was otherwise difficult to obtain and or involved tremendous inputs for its collection. An attempt in the direction of assessing the landuse land cover condition on the bsis of remote sensing products and of field visits to different parts of Ahmednagar plateau. Deals with three important aspects of land as a resource, such as Physiography and drainage characteristics Landuse land cover conditions and the materials particularly the wide spread occurrence of red boles in the region.

3 illus, 4 ref

006352   Lall D;Dahiya S S;Lailer P C;Chauhan T R; Punia B S (Div of Buffalo Nutr, Cent Inst for Res on Buffaloes, Sirsa Road, Hisar-125 001) : Utilization of certain essential minerals in buffalo calves fed on farm ration. Indian J Anim Nutr 2002, (19)3, 204-09.

Utilization of essential minerals (Ca, P, Mg, Fe, Zn, Mn and Cu) in buffalo calves was investigated by the comparative balance technique. Twelve buffalo calves (150-200 Kg) divided into two groups of six each were fed a common farm ration consisting of concentrate mixture (CM), green jowar and wheat straw. The CM of group I was supplemented with a standard mineral mixture @ 3% (2% min. mix+1% salt), where as CM of group II did not contain any mineral mixture. A mineral balance trial was conducted after a preliminary feeding period of 30 days. The net availability of the each mineral was calculated (as percentage) by dividing the difference of the daily mean balance of the two groups by the difference of their total intake. These values were 48.20% for Ca; 53% for P; 59.9% for Mg; 10% for Fe; 26.1% for Zn; 42.3% for Mn 53.8% for Cu respectively. These values were comparable to the results published in the temperate zones but low in case of Zn and Fe indicating an increase in the requirements of Zn for buffalo calves fed normal farm ration, but not in case of Fe due to its abundant supply through feed.

3 tables, 19 ref

006351   Harish V;Basavarajappa H T (Dep of Studies in Geol, Univer of Mysore, Manasagangotri, Mysore-6) : Provenance and depositional environmenta of late proterozoic siliciclastic sequence of kurnool group, Andhra Pradesh. J Indian Ass Sedimentologists 2001, 20(2), 207-22.

Petrographic studies of the siliciclastic strata of Kurnool Group have reveled quartz as the dominant detrital constituent with subordinate feldspar and rock fragments. The sediments are medium to fine grained, very well sorted to well sorted, negatively to positively skewed and platykurtic to leptokurtic in nature. Grainsize distribution curves indicate that the sediments are transported mainly as saltation. Environmental interpretations based on various bivariate, multivariate and log log plots of size parameters indicates the deposition of sediments in a beach to shallow marine environment. The surface featurs of quartz grains reveals marine depositional environment and Archaean crystalline source. Primary sedimentary structures like ripple marks and cross stratification indicate the deposition of sediments in shallow water. Heavy mineral assemblage suggests that plutonic igneous, metamorphic and networked sediments formed the ultimate source of heavy minerals for the Kurnool siliciclastics. From the petrographic and textural analysis it is reveled that the siliciclastics of Kurnool Group had their source from the Archaean granites and gneisses and underlying Cuddapah sediments and deposited in a beach to shallow marine environment,

12 illus, 4 tables, 50 ref

006350   Hanumanthu R C;Padmasree P (Geo Dep, S V Univ, Tirupati) : On the origin of metavolcanics and granitoids of Kadiri schist belt, Anantapur district, Andhra Pradesh. Indian Mineralogist 2002, 36-37(2,1), 31-44.

Kadiri schist belt lies in the eastern tectonic block of Dharwar craton and consists predominantly of meta-acid volcanics with minor amounts of meta basic rocks. The schist belt is flanked by younger granitoids. Geochemical studies suggest that the meta-volcanics of the schist belt display tholeiitic to calc-alkaline affinity. The granitoids are magmatic, metaluminous, calc-alkaline and are grouped under 1-type. The various lines of evidence suggest an island arc and continental margin tectonic setting which seems to be the suitable model for the evolution of Kadiri schist belt

11 illus, 3 tables, 35 ref

006349   Habib I;Jalaluddin;Chaturvedi U K (Dep of Bot, Veer Bhumi Govt P G Coll, Mahoba-210 427) : Limnological studies on Betwa river at Hamirpur - preliminary observations. Biosphere 2002, 7(1-2), 23-5.

A preliminary survey of Betwa river at Hamirpur was carried out to assess the phytoplankton composition and physico-chemical characteristics. The river differs considerably in physico-chemical and biological data at different sampling stations. Diatoms showed a good response as to abundance in the river. The river was found to be moderately alkaline with pH ranging from 7.8-8.0. Low concentration of various nutrients is a special feature of the river.

1 table, 14 ref

006348   Gupta A;Tiwari G N (Centre for Energy Studies, Indian Inst of Technol Delhi, New Delhi-110 016) : Performance evaluation of greenhouse for different climatic zones of India. SESI Jl 2002, 12(1), 45-57.

An attempt has been made to predict the comparative performance of different configurations of greenhouses having equal floor area and central height. A mathematical simulation model has been used for carrying out numerical analysis corresponding to the climatic conditions of four Indian cities viz. New Delhi, Jodhpur, Chennai and Srinagar, representing four different climatic zones in the country. Indoor air temperatures in greenhouses have been evaluated for a typical summer and winter day in these four locations. The results indicate that the greenhouse with modified arch and modified IARI configurations perform better where cooling is required; whereas, the design configuration of uneven span with a north wall (NW) is found suitable for the cold places requiring heating.

7 illus, 2 tables, 9 ref

006347   Govindaraju S;Govindaiah S;Srikantappa C (Geo Studies Dep, Mysore Univ, Manasagangothri, Mysore-6) : Petrology, geochemistry and P-T conditions of metamorphism of supracrustal rocks of Nellore-Mica belt of Andhra Pradesh, South India. Indian Mineralogist 2002, 36-37(2,1), 62-75.

The Nellore Mica Belt forming part of the Nellore schist belt is composed of quartzites, metapelites (kyanite/silimanite+garnet+biotite+muscovite), iron-stones and amphibolites (plagioclase+hornblende+clinopyroxene). These supracrustal rocks are considered to be equivalent to Sargur group in the Dharwar Craton. They are intruded by pink to grey granites as well as ruby and green mica-garnet-tourmaline and beryl-bearing zoned pegmatites. The schists are grouped into two categories, the quartz-garnet-biotite-muscovite schists which are characterised by low SiO₂ and alkalies, enriched in Fe₂O₃¹, TiO₂, MgO and CaO, group-2, The garnet- kyanite- staurolite- mica schist which are charcterised by their higher SiO₂ and Al₂O₃ content and lesser amounts of Fe₂O₃¹, MgO, TiO₂ and CaO. The second group of schists compare well with the pelitic schists of Holenarasipur schist belt. Garnetiferous amphibolites contain higher Fe₂O₃ than those of non-garnetiferous amphibolites. The composition of plagioclase in schists and amphobolites vary in its anorthite content from An₃₀ to An₄₀ and amphiboles are alumino-tschermakite in composition.

9 illus, 2 tables, 27 ref

006346   Gopalakrishna G S;Ashamanjari K G;Prasad J S; Mahesh M J;Madhu S P (Geo Studies Dep, Mysore Univ, Manasagangotri, Mysore-570 006) : Hydrothermal synthesis and characterization of sodium alumina phosphate mineral. Indian Mineralogist 2002, 36-37(2,1), 57-61.

Na₂AlH₃(P₂O₇) compound was synthesized by hydrothermal method and characterized by FTIR, DTA, XRD, wet chemical analysis and impedance spectroscopy measurements. Results indicate that pyrophosphate is a prospective fast ionic conductor with relatively high thermal stability

3 illus, 9 ref

006345   Deswandikar A (NO, , 13/20 Myrike Rd., Bankstown, Sydney, Australia) : Fossil sedimentary deposits on shrivardhan coast of Maharashtra India. Trans Inst Indian Geogr 2001, 23(1-2), 119-25.

Deals with the general distribution of regressive, fossil sand deposits and their relationship with sediments in the surrounding area, their topographic position, morphology and stratigraphy with special reference to fossil deposits at Shekhadi on Shrivardhan coast. it also tries to ascertain the relative level of sea indicated by these fossil deposits in the area. The coastline has preserved fossil sedimentory formations mainly on Shrivardhan coast between 18° 5' N and 18° 15' N latitudes and the beach rock formations can be located all along this stretch. Here the formations are thick and intact.

3 illus, 1 table, 13 ref

006344   Chandrasekar N;Rajmanickam G V (Dep of Geol, V O Chidambaram College, Tuticorin-628 008) : Nature of distribution of heavy minerals along the beaches of central Tamil Nadu coast. J Indian Ass Sedimentologists 2001, 20(2), 167-80.

The average heavy mineral distribution of the sediments of the Central Tamil Nadu coast region varies from 1.27 to 63.86 percent. As per the zonal grouping the averages of the heavy mineral distribution, the south is comprised of 25.6 percent, while the center 20.54 percent and north 7.96 percent. Heavy mineral constituents are opaques, zircon, garnet, epidote, kyanite, monazite, rutile, silimanite and staurolite. The angularity of the heavy minerals and the distribution variation in the different grain size directs the role of differential grain size sorting. The texture of the heavy minerals of the individual nature is noticed from euhedral to rounded. Such strong mix up of the heavy mineral grains suggest multi sources. The highly resistive detrital heavy minerals indicate the presence of zoning, etch marks and roundness. Such features reflect the role of recycling in the transportation of sediments. The heavy mineral assemblage suggests the nature of source rocks comprising charnockites, high grade metamorphic and early sediments.

7 illus, 2 tables, 30 ref

006343   Chandrasekar N;Cherian A;Rajamanickam M; Rajamanickam G V (Chem and Marine Geochem Res Lab, SPIC Res Cen, V O Chidambaram College, Tuticorin-628 008) : Influence of garnet sand mining on beach sediment dynamics between periathalai and navaladi coast, Tamilnadu. J Indian Ass Sedimentologists 2001, 20(2), 223-33.

To understand erosional and accretional behaviour on beach configuration due to garnet mining in the beaches between Periathalai and Navaladi Coast, measurements of beach profile over a year of summer, NE and SW monsoons (year 2000) have been carried out. It revealed temporal changes in beach configuration in response to mining. Subaerial sand volumes above specific contour was evaluated. The average sand volume is 50m³/m. Suspended sediment was evaluated along the coast using sea truth and Landsat Thermatic Mapper (TM) data of 1993. Supended Sediment Concentration (SSC) ranges from 4.3 to 20.8 mg/l in SW monsoon and 1.9 to 14.6 mg/l in NE monsoon.

8 illus, 3 tables, 26 ref

006342   Borbora N J;Kataki T (Dep of Appl Geol, Dibrugarh Univ, Dibrugarh, Assam-786 004) : Sedimentological studies of barail and tipam sandstones, around Jairampur, Arunachal Pradesh. J Indian Ass Sedimentologists 2001, 20(2), 181-94.

The Barail and Tipam Group of sandstones around Jairampur of Arunachal Pradesh are classified based on petrographic studies as lithic graywackes and sublitharenite respectively. Both the sandstones are comprised of angular to subangular grains; poor to moderately sorted with scattered mica, chlorite, cement, matrix and other constituents. Elongate to subequant quartz grains constitute the dominating framework mineral, with lithic fragments and feldspar in subordinate amount. Overgrowth of quartz, penetration of calcite along cracks of quartz and vice-versa, development of authigenic mica suggests the effects of tectonism and diagenesis. Results of bivariant plots indicate the environment of deposition as shallowing up deltaic for Barail and fluvial for Tipam sediments, dominated by tractive and turbidite conditions. The characteristics and relative abundance of heavy minerals indicate the source to be mainly from igneous and metamorphic terrain with possible derivation of Barail sediments mainly from basic igneous rocks.

6 illus, 3 tables, 25 ref

006341   Bhattacharya D K;Barla V C (Postgraduate Geo Dep, Ranchi Coll, Ranchi-834 008) : Geochemistry and genesis of magnetite deposits and associated metaultramafics around Nawadih, Palamau District, Jharkhand. Indian Mineralogist 2002, 36-37(2,1), 45-56.

In Nawadih, magnetite mineralisation occurs in metamorphosed ultramafic rocks as pockets, bands and disseminations. The metaultramites are characterised by low concentration of incompatible elements and have high Mg-values indicating a depleted mantle inheritance. Field, petrographic and geochemical signatures suggest that the magnetites are early magmetic crystalline phase of a high magnesium rich magma undergoing fractional crystallisation and gravitative accumulation under high Po₂

5 illus, 4 tables, 24 ref

006340   Basavarajappa H T;Narasimha K N P;Srikantappa C (Geo Dep, Mysore University, Manasagangotri, Mysore-570 006) : Petrography and P-T conditions of metamorphism of Sargur group of rocks around Hadinaru, Mysore district. Indian Mineralogist 2002, 36-37(2,1), 102-09.

Supracrustal rocks like calc-silicates, quartzites, banded iron formations interbanded with mafic and ultramafic rocks belonging to Sargur group are very well exposed around Hadinaru in Mysore District. Field and petrographic study indicate that these rocks have been deformed and metamorphosed. Mineral chemistry of garnet, biotite and amphiboles indicate considerable variation in their chemistry related to bulk composition of the rocks. The coexisting garnet- biotite and plagioclase-amphibole thermometry yield temperature of 630°-650° C suggesting that the rocks have been subjected to upper amphibolite facies conditions of regional metamorphism, much similar to the P-T conditions that prevalied around Sargur area.

2 illus, 2 tables, 7 ref

006339   Baruah H;Das P K (Geol Dep, Arya Vidyapeeth Coll, Guwahati-781 016) : Petrography of the Singrimari sandstones, west Garo hills district, Meghalaya and Dhubri district, Assam, India. J Indian Ass Sedimentologists 2001, 20(2), 125-40.

Singrimari Sandstones are of two types-a basal coarse and an upper fine variety. Mineralogy wise, both are feldspathi sandstones. Provenance of both the distributions may be traced back to a nearby continental block with somewhat unstable basement. A distinct medium to high grade metamorphic and igenous source rocks is substantated by heavy minerals. The detritus of both the sandstones were laid under semi-humid to semi-arid climatic conditions. There was less influence of wear and tear with intermittent abrasion. Pressure effects, seen mainly in the basal sandstones, are more vivid than other elements of diagenesis. Mineralogical maturity of both the distributions is a post-depositional effect.

12 illus, 3 tables, 32 ref

006338   Abdu Hassan A S (Geography Dep, University of Pune, Pune) : Geomorphological characteristics of Wadi Zabid basin (Yemen). Trans Inst Indian Geogr 2001, 23(1-2), 127-37.

Since topography is one of the principal basin characteristics affecting stream flow, this aims to analyze the morpology of the Wadi Zabid basin using the Digital Elevation Model (DEM), which has been developed for the wadi basin. The creation of the DEM enables more understanding of the basin landscape. In addition, carried out morphometric analysis of drainage network in order to show the morphometric characteristics of the drainage basin of Wodi Zabid.

6 illus, 1 table, 12 ref

005493   Yaping Shao;Sixiong zhao (NO, City University of Hong Knog, Hong Knog, China) : Wind erosion and wind erosion research in China. Ann Arid Zone 2001, 40(3), 317-36.

The past few years have seen an alarming increase in the frequency and intensity of dust storms in Northwest China, which is known to be a major dust source in the world. This outstanding environmental issue is an active research field in China, with the participation of a large number of research groups and scientists from various disciplines. An attempt has been made to give an overview of the wind erosion problem in China and to provide a review of the research activities and recent results published in Chinese journals. The review covers four different research areas, including wind erosion climate, monitoring, mechanism and modeling.

^iia15 illus, 5 tables, 16 ref

005492   Xiao-Yong;De-Lian Liu;Jin-Xing Dai (School of Earth and Space Sciences, University of Science and Technology of China, Hefei-230 026) : Extremely H₂-rich fluid inclusions in eclogite from Dabie Shan orogenic belt, eastern China. J Geol Soc India 2003, 61(1), 101-2.

Eclogites in the Dabie Shan terranes have recorded the physico-chemical properties of crustal materials which underwent the Triassic ultra-high pressure (UHP) metamorphism at mantle depths. Identification of coesite and micro-diamond in different eclogite localities of the region (Okay et al. 1989; Wang et al. 1989; Xu et al. 1992) demonstrates that supracrustal materials can be subducted to mantle depth of at least 120 km. Reports extremely rich H₂-bearing fluid inclusions from UHP eclogites from the Dabie Shan orogenic belt.

^ssc2 tables, 7 ref

005491   Van Donk S J;Skidmore E L (NO, Wind Erosion Research Unit, USDA-ARS, 1515 College Avenue, Manhattan, KS 66502, USA) : Field experiments for evaluating wind erosion models. Ann Arid Zone 2001, 40(3), 281-302.

Reviews wind erosion field research, emphasizing recent contributions, and describes experiments and measurements required to evaluate wind erosion models. Three types of data are needed to evaluate wind erosion models; airborne sediment flux, meteorological data and data describing the condition of the field surface. The Big Spring Number Eight (BSNE) and the Modified Wilson and Cooke (MWAC) samplers are the most widely used collectors of airbrne sediment. The Sensit and the Saltiphone do not collect sediment, but continuously record the occurrence and intensity of saltating particles. Additional work is needed to investigate their use for the actual quantification of sediment flux. Several researchers have developed some type of continuously weighing sampler a sampler and an electronic scale combined in one apparatus. These devices are not yet fully operational and are expensive. Their cost has to decrease if they are to be used more widely. More research is also needed on methods to continuously measure soil moisture at the soil surface. Radiation data such as surface albedo may be useful in this regard.

12 illus, 74 ref

005490   Thomas T;Jaiswal R K (NO, National Institute of Hydrology, Ganga Plains South Regional Centre, 278 Manorama Colony, Sagar-470 001) : Hydrologic modelling of ungauged watersheds in central India. J Instn Engrs-Pt CI 2002, 83(Nov), 186-90.

The SCS Curve Number model has been applied for estimation of runoff in the Sonar, Bearma and Bebas river basins, which are the sub-basins of the Ken river system. These basins have been sub-divided into smaller sub-basins and the runoff of each of these sub-basins has been computed, after establishing respective SCS curve numbers. The discharges at the outlets of the Sonar, Bearma and Bebas basins have been computed by adding the runoff from its sub-basins, considering the time lag wherever applicable. The predicted runoff at the outlet of these basins are quite in agreement with the available observed direct surface runoff, which implies that the sub-basin wise runoff estimation is satisfactory.

2 illus, 3 tables, 12 ref

005489   Tatarko J (NO, USDA-ARS Wind Erosion Research Unit, 1515 College Avenue; Manhattan, Kansas 66502, USA) : Soil aggregation and wind erosion processes and measurements. Ann Arid Zone 2001, 40(3), 251-63.

The size distribution and stability of soil aggregates have a major influence on the wind erodibility of soils. From dield and laboratory studies, it is known that aggregate status is the result of external forces acting on the soil such as tillage, wetting and drying, freezing and thawing, and freeze drying. The effect of these forces varies with soil properties, cropping management, and the severity of the processes. As a result of these forces, soil aggregates may either increase or decrease in size as well as stability. The effects of moisture and temperature can cause significant changes in the aggregates and thus, the erodibility of a soil. In order to relate the forces acting on soils to different properties and to wind erodibility, standardized methods are needed to measure the aggregate size distribution and aggregate stability. Standardizing these methods would allow comparison of the effects of various treatments and soil types on the aggregate status. Reviews the processes and measurement of soil aggregation as it affects wind erosion.

2 illus, 57 ref

005488   Sterk G;Riksen M;Goossens D (Erosion and Soil and Water Conservation Group, Environmental Science D, Wageningen University, Nieuwe Kanall 11, 6709 PA Wageningen, The Netherlands) : Dryland degradation by wind erosion and its control. Ann Arid Zone 2001, 40(3), 351-67.

Global population growth is expected to impose an increasing pressure on agricultural production in the world's drylands, which cover approximately 41% of the continental area. The land resources in drylands are severely theratened by soil degradation, with wind erosion being one of the major degradation processes. It causes sedimentation at undesired places, crop damage by sand blasting and burial, deterioration of soil structure, a loss of soil fertility, and it affects the water economy in the topsoil. On drylands in developing countries, adequate wind erosion control is currently not achieved due to poor socio-economic conditions, low crop biomass production, crop competition and management constraints. A potential solution is to make use of the natural dryland vegetation of scattered trees and shrubs. More research is needed to better understand the effects of scattered vegetation on wind speed and erosion, as well as on particle deposition and accumulation. This should lead to models that can help develop location-specific wind erosion control strategies.

4 illus, 5 tables, 53 ref

005487   Sivabalan R;Rengaraj S;Murugesan V (Chemistry Dep, Anna University, Chennai-600 025) : Fluoride uptake characteristics of activated carbon from agricultural-waste. J scient ind Res 2002, 61(12), 1039-45.

Removal of excess fluoride from ground water to within the permissible limits of 1.0-1.5 mg/L is the only way to control fluorosis. Batch and column type experiments were carried out for the adsorption of fluoride using activated carbon prepared from palm seed coat (PSCC) by dolomite process. In the batch study, influence of pH, adsorbent dose, contact time and initial fluoride concentration was investigated. Adsorption of fluoride was pH dependent and higher removal efficiencies were observed in the pH range of 4.8. Fluoride removal increased with dosage of carbon. A low concentration aluminium sulphate solution (2 per cent) effectively regenerated the exhausted carbon bed. The adsorption process obeyed Freundlich adsorption isotherm. The kinetic studies revealed that the forward rate constant was comparatively much higher than the backward rate constant. Continuous flow experiments in fixed bed columns were carried out with ground water in order to assess the feasibility of this carbon for field application. The performance of the carbon in fluoride removal was studied as a function of flow rate, initial fluoride level and particle size of the adsorbent. Fluoride removal increased with decreasing particle size of the carbon. The interesting feature of the study was that the defluoridation capacity increased with increase in the initial fluoride ion concentration.

6 illus, 1 table, 24 ref

005486   Singh M P;Singh A K (Geology Dep, Banaras Hindu University, Varanasi-221 005) : Hydrocarbon emigration through microfracturing in vitrinite: an example from the oligocene coals of Borjan coalfield, Nagaland. J Geol Soc India 2003, 61(2), 170-6.

Borjan coalfield is situated on the western flank of the Naga Hills in the Mon district of Nagaland. Pillar coal samples from Watking and Kongan seams were subjected to detailed petrographic and geochemical investigations for the assessment of their source rock characteristics. During petrographic examination, emigration of exsudatinite (waxy oil) from a microfracture in vitrinite (telocollinite / collotelenite) has been observed. This is a rarely reported visible evidence of primary migration of oil in coal through microfracturing.

3 illus, 1 table, 8 ref

005485   Siddheshwar P G;Sri Krishna C V (DSA Centre in Fluid Mechanics, Mathematics Dep, Bangalore University, Bangalore-560 001) : Effects of non-uniform basic temperature gradient and earth's rotation on convection in a viscoelastic fluid-filled high-porosity mantle. J Indian Geophys Union 2002, 6(1), 7-13.

Mantle convection is studied in the presence of a non-uniform basic temperature gradient and earth's rotation. Based on an observation by Lowrie (1997) on the nature of the mantle fluid, model the mantle situation as a Rayleigh-Benard problem involving a viscodastic fluid-filled high-porosity medium. Due to the complexity of the basic flow andn conjtainment conditions the eigenvalue is obtained numerically. The analysis predicts that the eigenvalue of the corresponding Newtonian problem overpredicts the eigenvalue of the viscoelastic problem. The preterred mode of oscillatory motion sets in for lower rotations with viscoelasticity having opposing influences on the stability of the system. Among the six non-uniform temperature gradients considered, the most unstable is the step function profile. Illustrates mantle convection together with some important mechanisms of controlling convection.

5 illus, 26 ref

005484   Sharma R;Pervez S (Chemistry Dep, Government V.Y.T. Postgraduate Autonomous College, Durg-491 001) : Spatial variability of ambient particulate matter around a phosphatic fertilizer plant in India. J scient ind Res 2002, 61(12), 1077-83.

Monitoring of ambient PM₁₀ and SPM levels in the vicinity of a phosphatic fertilizer plant located at Kumhari, Chhattisgarh was carried out using two sets of Respirable dust Sampler (RDS) and High Volume Sampler (HVS). The specific objecties were the determination of spatial and seasonal variability of levels of ambient particulates, and their relationship with the phosphatic fertilizer plant emissions. Samples were collected in post-rainy, winter and summer seasons (September 2000-June 2001). The results have shown a marked seasonal trend and spatial variability of ambient particulate levels in the study area that were higher in winter and lower in summer while in post-rainy period, levels were far less than other two seasons. Higher concentrations of ambient PM₁₀ and SPM were found in downwind monitoring stations compared to upwind direction. Seasonal variation in transport pattern of PM₁₀ and SPM was also observed. Monitoring stations at a distance of 4km downwind have shown highest susceptibility of PM₁₀ in post-rainy and summer seasons while in winter it was found at 2 km downwind. In the case of SPM, highest susceptible location was found at 2km downwind in all the three seasons. Ratios of PM₁₀ to SPM and correlation coefficient values between both size of particulate matter along with meteorological parameters were also worked out.

2 illus, 3 tables, 27 ref

005483   Sharma R;Banerji S;Pandit M K (NO, Wadia Institute of Himalayan Geology, 33, G.M.S. Road, Dehra Dun-248 001) : W-mineralization in Sewariya area, south Delhi fold belt, northwestern India: fluid inclusion evidence for tungsten transport and conditions of ore formation. J Geol Soc India 2003, 61(1), 37-50.

The S-type, high-level, biotite granite (Sewariya Granite) intruding the metasediments of the South Delhi Fold Belt in central Rajasthan hosts W-mineralization that occurs within the shear controlled late-stage quartz veins. The fluid inclusion data of the observed type 1 to type 4 inclusions in mineralized quartz veins and type 1, type 2 inclusions in fluorite reveal that the high to low temperature alkali chloride solution was in equilibrium with syn to post W-mineralization events. Boiling at a temperature range of 373 to 417°C is recorded in the earliest fluid inclusion viz. gas rich type 2 and liquid rich type 3 inclusions, which together show a continuum in the fluid density from 0.2 to 0.85 g/cm³. Dominance of high saline aqueous fluid with 32.5 to 43.3 equiv. wt percent NaCl is represented in type 1 inclusions. The increase in salinity to the extent of T_m NaCl<62> T_h L-V is attributed to the boiling of fluid and successive influx of high saline hydrothermal fluid exsolved from crystallizing granite source rocks. Type 1 inclusions of fluorite show a difference from type 1 inclusions of mineralized quartz in terms of their lower temperature and a common T_h <62> T_m NaCl homogenization trend. Type 4 inclusions are secondary mostly homogenized below 170°C, these are unrelated to the mineralization event.

8 illus, 2 tables, 53 ref

005482   Sharma B K;Bhola A M;Scheidegger A E (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : Neotectonic activity in the Chamba Nappe of the Himachal Himalaya: jointing control of the drainage patterns. J Geol Soc India 2003, 61(2), 159-69.

Study of the possible correlation between kink-band, joining and drainage patterns in the Chamba nappe (Himachal Himalaya) shows a correspondence between the valley trends and the joints, indicating a neotectonic control of both features. However, no correlation exists between the Precambrian to Upper Paleozoic conjugate kink-bands and the joint/valley orientations, showing that there was a fundamental change in the tectonic pattern between the Upper Palaeozoic and the recent ongoing crustal adjustment in the Himachal Himalaya.

7 illus, 4 tables, 11 ref

005481   Sharma B K;Bhola A M;Scheidegger A E (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : Neotectonic activity in the Chamba Nappe of the Himachal Himalaya: jointing control of the drainage patterns. J Geol Soc India 2003, 61(2), 159-69.

Study of the possible correlation between kink-band, joining and drainage patterns in the Chamba nappe (Himachal Himalaya) shows a correspondence between the valley trends and the joints, indicating a neotectonic control of both features. However, no correlation exists between the Precambrian to Upper Paleozoic conjugate kink-bands and the present joint/valley orientations, showing that there was a fundamental change in the tectonic pattern between the Upper Palaeozoic and the recent ongoing crustal adjustment in the Himachal Himalaya.

7 illus, 4 tables, 11 ref

005480   Shao Y (Physics and Materials Science Dep, City University of Hong Kong, Hong Kong, SAR, China) : Recent developments in wind erosion research. Ann Arid Zone 2001, 40(3), 221-32.

Wind erosion recently become a key focus of many different research disciplines, such as climate change, air quality, sustainable land use, etc. Discusses the importance of wind erosion in these research fields. It is also attempted to provide an outline of recent progresses in wind erosion studies from the perspectives of wind erosion monitoring, field experiments and modeling.

3 illus, 37 ref

005479   Sethna S F (Geology Dep, St. Xavier's College, Mumbai-400 001) : Occurrence of acid and intermediate rocks in the deccan volcanic province with associated high positive gravity anomalies and their probable significance. J Geol Soc India 2003, 61(2), 220-2.

Occurrence of intermediate and acid rocks such as trachyte and rhyolite are known to occur mainly along the west coast around Mumbai and in the Saurashtra area, such as in Girnar, Barda, Osham and Alech hills. There are also other isolated occurrences in Phenai Mata region and pavagadh hill (Sethna, 1989). It is interesting to note that both along the west coast near Mumbai and in the Saurashtra area there are occurrences of relatively high positive gravity anomalies of upto +70 mGal Bouguer anomaly. It seems unlikely that such a close spatial relationship of these anomalies, and the occurrence of more evolved rock types could be entirely fortuitous. Whilst, intuitively, negative gravity anomalies might be expected in areas where less dense, evolved rocks occur, thought should be given as to the petrogenesis and possible origin of these evolved rocks.

^ssc7 ref

005478   Sethna B S;Kothare P (Geology Dep, St. Xavier's College, Mumbai-400 001) : Petrology and mineralogy of ankaramite in the Deccan Volcanic Province of Rajkot district, Saurashtra, Gujarat. J Geol Soc India 2003, 61(1), 97-100.

The occurrence of ankaramite in the Deccan Volcanic Province of Saurashtra is reported here. The ankaramite occurs as a small dyke intruding into horizontal basalt flows. Petrographically it is characterised by the presence of large phenocrysts of clinopyroxene (chromian diopside) and olivine (Fo₈₃) in a groundmass of plagioclase (AN₆₀), iron oxides and accessory brown amphibole (kaersutite). Chemically it is characterised by enrichment in high field strength and light rare earth elements as compared to the picritic olivine dolerites of the area. It is concluded that the ankaramite magma represents a primitive sample of High-Ti type of tholeiitic basaltic magma while majority of the olivine dolerites and dolerites found in the area are representative of Low-Ti type of tholeiitic magma.

2 illus, 1 table, 9 ref

005477   Satyanarayana Y;Anand G V;Saha A A;Naithani S;Murty G R K (NO, Naval Physical Occanographic Laboratory, Kochi-682 021) : Estimation of geoacoustic parameters using matched field inversion. J Indian Geophys Union 2002, 6(1), 15-8.

Acoustic properties like compressional speed, shear speed, compressional and shear wave attenutation of different layers of the seabed, known as geoacoustic parameters, play a key role in underwater acoustic propagation. These parameters can be obtained from some direct and indirect measurements subject to certain limitation and assumptions. Seismic inversion techniques are commonly used to compute velocity (interval or rms) of different strata. Matched Field processing (MFP) inversion techniques to derive the geoacoustic parameters from a synthetic acoustic pressure field computed using the normal mode approach has been applied. The basic input required to generate pressure field is thickness of different layers, density and their compressional speed and attenutation. No shear speed or attenuation has been taken into account. The inversion results show good correlation with the input values of parameters. However there is some deviation in the values of low sensitive parameters like thickness of the lower substrata.

1 illus, 1 table, 9 ref

005476   Saraswati P K;Shimoike K;Iwao K;Mitra A (Earth Sciences Dep, Indian Institute of Technology, Powai, Mumbai-400 076) : Distribution of larger foraminifera in the reef sediments of Akajima, Okinawa, Japan. J Geol Soc India 2003, 61(1), 16-21.

Examines the bathymetric distribution of larger foraminiferal species on the reef flat and reef slope of Akajima Island, located near Okinawa in the Ryukyu island arc of Japan. It also estimates the total skeletal carbonates contributed by larger foraminifera in the reef sediments of this island. Three distinct assemblages are recognized with increasing water-depths: Marginopora vertebralis and Baculogypsina sphaerulata are confined to reef flat, occurring at a water depth of 1.5 m, Peneroplis planatus and Neorotalia calcar occur within 30 m bathymetry followed down depth by Operculina ammonoides, Nummulites venosus, Alveolinella quoyi and Baculogypsinoides spinosus between 30 and 60 m. Cycloclypeus is the deepest dwelling genus, making its first appearance at 60 m. Larger foraminifera contributed about 5.8% of the sediments accumulated on reef flat and reef slope of Akajima, which is significantly higher than the global average. There is considerable variation in relative contributions by miliolids and rotaliids on reef flat and reef slope. On the flat, miliolids contribute 64 percent of the total skeletal carbonates produced by larger foraminifera, whereas on reef slope it contributes only about 5%.

1 illus, 2 tables, 8 ref

005475   Sant D A;Rangarajan G (Department of Geology, M S University of Baroda, Vadodara-390 002) : Onset of climate change at last glacial-holocene transition: Role of the tropical Pacific. Curr Sci 2002, 83(11), 1398-1402.

Studies palaeoclimatic records from various sites spread around the earth, focusing on the start of the last glacial-interglacial transition. The warming, as recorded in the δ¹⁸O record started first in the tropics, then propagated to the Antarctic and then finally to the Arctic. Data analysis suggests that it took about 7.6 ka for onset of climate change to propagate globally. Proposes that the tropical Pacific played a major role in initiating the warming in the tropics. Discusses mechanisms that could have transported this heat from the tropics to Antarctica and then to the Arctic during transition to the interglacial.

3 illus, 32 ref

005474   Roy I;Sarkar B C (Applied Geology Dep, Indian School of Mines, Dhanbad-826 004) : Prototype development of MODELER: a knowledge based system for identification of iron ore deposit types. J Geol Soc India 2003, 61(2), 177-84.

Geological knowledge of associations between field evidence and deposit types for a range of iron ore deposits have been consolidated and structured into a rule-based prototype system, MODELER that is able to assist exploration geologist for diagnosing iron ore deposit types. The system contains knowledge on eighteen deposit models represented by eighteen compound rules based on the concepts of type area and genetic type. Focuses on the design and development of the system and its application to five ore deposits from eastern India.

3 illus, 3 tables, 17 ref

005473   Reddy T A K;Sridhar M;Ravi S;Chakravarthi V; Neelakantam S (NO, , 3-5-170/G, Narayanguda, Hyderabad-500 029) : Petrography and geochemistry of the Krishna lamproite field, Andhra Pradesh. J Geol Soc India 2003, 61(2), 131-46.

The lampriotes contain glass, numerous vesicles, and xenoliths of the basement granite-gneiss, dolerite and probably platformal sediments of the Cuddapah Basin, besides exhibiting fragmental and pyroclastic textures suggestive of near-surface emplacement. Radiometric age determinations suggests emplacement of these lamproites took place around 1224±14 Ma, probably during the reactivation of major crustal lineaments coinciding with the uplift of the mid-Proterozoic Nallamalai sediments of the Cuddapah Basin. Diopside, phlogopite, tetra-ferri phlogopite, richterite, sanidine, apatite and pseudomorphs of leucite, enstatite and olivine are the major primary constituent minerals present. Diopside-leucite-lamproite, phlogopite-leucite-lamproite, olivine-lamproite and richterite-phlogopite-lamproites are the variants. The bodies are ultrapotassic (molar K₂O/Na₂O<62>10), and contain high TiO₂, P₂O₅, K₂O, MgO, Ba, Sr, Zr, Cr, Ni, La and Ce, pointing to crystallisation from typical lamproite magma. The presence of mantle periodite xenoliths and xenocrystic minerals such as chrome-diopside, spinel and garnet indicate deep seated mantle derivation of the Krishna lamproites.

11 illus, 6 tables, 40 ref

005472   Rao S;Shirlal K G;Rao N B S (Applied Mechanics and Hydraulics Dep, Karnataka Regional Engineering College, Surathkal, Srinivasnagar-574 157) : Sediment trend matrix analysis along shore normal transects off Surathkal beach, Karnataka. J Geol Soc India 2003, 61(2), 215-9.

To study sediment travelling paths across shoreline in different seasons, sediment samples were collected normal to the shoreline along three profiles, separated by 220m from Surathkal beach near Karnataka Regional Engineering College (K.R.E.C.), Karnataka. The sediments were analysed for their grain size characteristics (statistical parameters) and sediment trend matrix was prepared. By using sediment trend matrix, sediment travelling paths were drawn. It has been found that during premonsoon, sediments were moving predominantly towards offshore region, resulting in erosion. Sediments were moving predominantly towards shore and build-up of beach takes place during the post monsoon season.

^ssc3 illus, 3 tables, 5 ref

005471   Prasad P S R;Gowd T N (Mineral Physics Div, National Geophysical Research Institute, Hyderabad-500 007) : FTIR spectroscopic study of hydroxyl ions in natural topaz. J Geol Soc India 2003, 61(2), 202-8.

Fourier transform infrared (FTIR) spectroscopic investigations on naturally occurring topaz sample were carried out in 400 - 5000 cm^-1 wave number range, using recently established facility in NGRI, to identify the nature of hydroxyl ions. Three bands were observed around 1162, 3646 and 4795 cm^-1, which were due to hydroxyl ions. A strong asymmetry in both (OH) stretching and combination modes, observed for the first time, confirm the nonequivalence of the proton sites in its crystal structure. Electron paramagnetic resonance (EPR) studies showed two resonance lines with `g' values of 2.01 and 1.967, confirming existence of naturally occurring crystallographic defects.

2 illus, 20 ref

005470   Paramasivan B;Vijayakumar K;Elango P (Equatorial Geophysical Research Laboratory, Indian Institute of Geomagnetism, Krishnapuram, Tirunelveli-627 011) : Migration of dip equator - ground geomagnetic survey. J Indian Geophys Union 2002, 6(1), 19-23.

Ground magnetic survey was conducted along two north-south traverses running along the coast of peninsular India between 8.0° and 8.5° N geographic latitudes with Declination Inclination Magnetometer (DIM) and Balanced Magnetometric Zero (BMZ). The migratory movement of the dip equator in two different longitude sectors is confirmed with the observations of `I' and `Z' with the above instruments.

1 illus, 5 ref

005469   Pandey D K;Mathur U B;Rakesh Singh;Tej Bahadur (Geology Dep, University of Rajasthan, Jaipur-302 004) : Late pleistocene coral-algal sediments of Chaya formation of Mithapur area, Jamnagar, Gujarat. J Geol Soc India 2003, 61(2), 195-201.

Chaya Formation (Late Pleistocene - Holocene) of Dwarka-Okha area in Saurashtra peninsula, Gujarat, is subdivided into the lower Okha Shall Limestone Member and the upper Aramda Reef Member. A ca 1.5m thick succession of coral-algal lithofacies of Aramda Reef member that has been radiometrically dated at Woods Hole Oceanographic Institute, U.S.A. to 41.2 - 18.3 ka, is exposed in a well section near Mithapur (district Jamnagar), and is described here. The environmental conditions during Late Pleistocene are also discussed.

5 illus, 1 table, 19 ref

005468   Nandargi S;Dhar O N (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : High frequency floods and their magnitudes in the Indian rivers. J Geol Soc India 2003, 61(1), 90-6.

Frequency of floods at gauge/discharge (G/D) sites of Indian rivers have been examined using the 14 year data of 1986 to 1999. Only the data of such G/D sites have been considered which have experienced ≥50 floods during this period. It is seen that such frequent floods do not occur in the central and peninsular rivers but only in northeast and north Indian rivers. In northeast India, such floods have occurred in 8 rivers inlcuding Brahmaputra at 12 G/D sites while in north India 9 rivers including the Ganga at 20 G/D sites have registered ≥50 floods. The worst flood-prone sites have been found on the Brahmaputra at Dibrugarh and on the Beki River at Road Bridge and on the Kose River at Baltara. These sites have experienced floods whose frequency is 150 to 177 in the 14 year period. The magnitude of flood deviations at different sites have also been examined. Deviations of the order of 5 m to 18 m above the respective danger level (D.L.) at G/D sites have been observed on some of these rivers. This study has shown thaenormous water resources are available in this country. Every attempt should and must be made to conserve it for use in deficient rainfall regions of the country through a system of reservoirs and canals.

3 illus, 3 tables, 15 ref

005467   Naik S;Purohit K M (Chemistry Dep, Regional Engineering College, Rourkela-769 008) : Water quality of river Brahamani in Sundargarh District, Orissa. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-III 2000, (NULL), 4-5.

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005466   Mishra B;Pal N;Ghosh S (Geology and Geophysics Dep, Indian Institute of Technology, Kharagpur-721 302) : Fluid evolution of the Mosabani and Rakha copper deposits, Singhbhum district, Jharkhand: evidence from fluid inclusion study of mineralized quartz veins. J Geol Soc India 2003, 61(1), 51-60.

Fluid inclusions in quartz from the mineralized quartz veins from the Mosabani and Rakha copper deposits were investigated. On the basis of petrography, two distinct types of primary inclusions were identified. These are low saline aqueous biphase inclusions and high saline halite-bearing polyphase inclusions. The halite-bearing inclusions mostly homogenized by halite dissolution, barring instances where homogenization was manifest by disappearance of the vapour bubble. Minimum entrapment pressure values were estimated by intersection of the halite liquid with the corresponding inclusion isochores. The ranges in P-T at the temperatures of halite dissolution are: 2,6 kb / 370 °C - 0.8 kb / 263°C for Mosabani and 2.1 kb / 270°C - 0.65 kb / 217°C for Rakha. Temperature-salinity plots for both the deposits is suggestive of restricted mixing (and simple cooling) of a host saline magmatic fluid with cooler low saline meteoric water that caused precipitation of sulphide minerals. Stable isotope data (δ¹⁸O and δD) from Changkakoti et al. (1987) are re-interpreted, leading to the conclusion that the main fluid component for Mosabani mineralization was either of magmatic/metasomatic parentage or an evolved meteoric water at a low water/rock ratio, after its interaction with a granitic pluton.

7 illus, 41 ref

005465   Maus S;Haak V (NO, GFZ Potsdam, Telegrafenberg, 14473, potsdam) : Is the long wavelength crustal magnetic field dominated by induced or by remanent magnetisation. J Indian Geophys Union 2002, 6(1), 1-5.

Crustal rocks carry remanent as well as induced magnetisation. In contrast to the remanent magnetisation, the induced magnetisation is aligned with and proportional in strength to the main magnetic field of the Earth. Attempt has been made to identify the nature of the crustal magnetisation by plotting the long wavelength power of the crustal magnetic field against the magnetic dip latitude. For predominantly remanent magnetisation, a weak increase in total intensity power with latitude, due to the preferential sampling of the weaker tangential part of the crustal field at the equator and the stronger radial part at the poles is expected to be seen. In contrast, a much stronger trend with latitude is expected for induced magnetisation because it is aligned to the main field and increases with its strength towards the poles. The result of investigation turns out to depend on the crustal field model used the in analysis. Some models show the strong trend with latitude expected for induced magnetisation, while others are consistent with purely remanent magnetisation. It is expects that crustal field models from the new Champ satellite data would be able to resolve the issue.

7 illus, 8 ref