Origin and geochemical characteristics of beryllium mineralization in the Zabara-Wadi El Gemal region,South Eastern Desert,Egypt

Beryl is the commercial source of beryllium and several varieties of it are valued as a gemstone.To contribute to understanding the mechanism of beryl formation,we carried out detailed geological,petrographical,and geochemical investigations on beryl mineralization occurrences in the Zabara-Wadi El Gemal(Z-WG)region.This region is an NW-SE trending tract that includes six berylhosting areas.The green gem variety of beryl(emerald)is restricted to phlogopite schist,pegmatite,and quartz veins.Prismatic hexagonal emerald crystals are well-developed in phlogopite schist and pegmatite.The gem variety emerald examined is sodic and Cr-dominant.It contains high concentrations of chromophore transition elements ordering Cr(up to 1511 ppm)>V(up to 242 ppm)>Sc(up to 245 ppm),giving rise to its vivid green color,refl ecting mafic-ultramafic source contribution.Among the investigated emeralds,the Sikait area contains the highest BeO(av.10.76wt.%)concentration.The compositional variability of emeralds is most likely attributed to the contribution from the host rocks.This is revealed by the examined emerald mineralization,for instance;the Abu Rusheid area(one of the best areas exposing rare metal-bearing granitoids)possesses the highest average of trace and REEs concentrations.In contrast,Um Kabu emerald has the highest contents of Co(av.20 ppm),Ni(av.299 ppm),MgO(av.8.2wt.%),Fe_(2)O_(3)(av.3.12wt.%),and CaO(avg.3.4wt.%)relative to other areas,which may be linked to contribution of ultramafic rocks exposed there.The proposed mechanism we suggest for emerald genesis is metasomatic interaction between felsic intrusions,that are enriched with K,Na,Be,Li,and B,with mafic-ultramafic rocks that are enriched in Cr,V,Mg,Fe,and Ca.This interaction is marked by the formation of phlogopite schist,the growth of emerald crystals,and desilicated pegmatite.

Classification, Tectonic Setting, and Mineralization Potential of Ayetoro and Sasaro Syenitic Plutons in Igarra Schist Belt, Southwestern Nigeria

Petrographic and geochemical studies of syenite-looking Ayetoro and Sasaro plutons within Igarra Schist Belt were carried out in order to classify them and determine their tectonic setting and mineralization potential. Petrographic study and geochemical classification revealed that while Ayetoro boss is microgranite constituting an aggregate of medium grained muscovite, quartz and biotite minerals, Sasaro stock is micromonzonite made up of medium grained albite, orthoclase, biotite, hornblende and pyroxene. Geotectonic setting showed the boss and stock are orogenic, probably derived from the same upper mantle magma as Igarra batholith that got contaminated by crustal materials responsible for their difference in lithology. Their mineralization potential showed that the massive Ayetoro microgranite with no appreciable trace-element contents cannot serve as host of any metallic deposit, and should be suitable for industrial applications. Whereas, the silicified, highly sheared Sasaro monzonite, with elevated level of some trace elements contents as Ag, Au and Cu, could harbor Ag-Au-Cu deposit.

Provenance of Precambrian Fe- and Al-rich Metapelites in the Yenisey Ridge and Kuznetsk Alatau, Siberia: Geochemical Signatures

Major, trace and rare earth element contents of Fe- and Al-rich metapelites from the Korda （Yenisey Ridge） and Amar （Kuznetsk Alatau） formations were determined to examine the nature, origin and evolution of their protoliths. Results indicate that these rocks are the redeposited and metamorphosed products of Precambrian kaolinitic weathering crusts, while the geochemical distinctions between the studied metapelites are determined by different weathering conditions in the source area and tectonic settings. The protolith of the Korda Formation metapelites was produced by erosion products of the post-Archean granitoid rocks, which accumulated under humid climate conditions in shallow-water basins along the continental margin. The geochemical characteristics of the deeper primary deposits of the Amar Formation suggest that volcanogenic material of mafic composition derived from an island-arc environment had a major role in supplying the erosion zone. These results agree with lithofacies data and with the geodynamic reconstruction of the evolution of the Yenisey Ridge and Kuznetsk Alatau during the Mesoproterozoic and Neoproterozoic, respectively. It was shown that REEs had limited mobility during contact metamorphism. The coherent mobility of REEs during collisional metamorphism may be attributed both to mineral reactions responsible for modal changes and to local chemical heterogeneity inherited from the initial protolith.

Neoproterozoic Tectonic Setting of Southeast China:New Constraints from SHRIMP U-Pb Zircon Ages and Petrographic Studies on the Mamianshan Group

Precambrian tectonic history of Zhejiaug, Fujian, and Jiangxi provinces of south China is important for understanding the tectonic evolution of South China but its magmatic activity, petrogenesis, stratigraphic sequence of the Mamianshan Group is still strongly controversial. Here we present new sensitive high resolution ion micro-probe （SHRIMP） U-Pb zircon geochronological data for the Mamianshan Group and petrographical data to constrain the tectonic framework of the regions. Our results showed that the SHRIMP U-Pb zircon age of green schists of the Dongyan Formation is 796.5±9.3 Ma, the Daling Formation is 756.2±7.2 Ma, and mica-quartz schist of the Longbeixi Formation is 825.5±9.8 Ma. These data indicate that the Mamianshan Group was formed not in the Mesoproterozoic, but in the Neoproterozoic and its stratigraphic sequences should be composed of Longbeixi, Dongyan, and Daling Formations from the bottom to the top. Rocks from this Group, from Zhejiang, Fujian and Jiangxi provinces, constituted the upper basement of the Cathaysia Block that overlay the lower basement of the Mayuan Group. Detailed petrographic studies demonstrate that the amphibole schists of the Dongyan Formation in the Mamianshan Group were formed within an intra-arc rift setting rather than a continental rift as previously suggested. Rather, this island-arc type formation was developed by collision and/or subduction between various blocks resulting from the breakup of the supercontinent Rodinia at c.850-750 Ma. The Zhuzhou conglomerate, distributed near Dikou Town, Jian＇ou City, Fujian Province and previously considered as evidence of the Mesoproterozoic Dikou movement, is shown here not to be the basal conglomerate above the angular unconformity between the upper and lower basements. Our conclusions have important implications for understanding the Precambrian tectonics of South China.

Correlations between ultrasonic pulse wave velocities and rock properties of quartz-mica schist

Physico-mechanical properties are critically important parameters for rocks. This study aims to examine some of the rock properties of quartz-mica schist（QMS） rocks in a cost-effective manner by establishing correlations between non-destructive and destructive tests. Using simple regression analysis, good correlations were obtained between the pulse wave velocities and the properties of QMS rocks. The results were further improved by using multiple regression analysis as compared to those obtained by the simple linear regression analysis. The results were also compared to the ones obtained by other empirical equations available. The general equations encompassing all types of rocks did not give reliable results of rock properties and showed large relative errors, ranging from 23% to 1146%. It is suggested that empirical correlations must be investigated separately for different types of rocks. The general empirical equations should not be used for the design and planning purposes before they are verified at least on one rock sample from the project site, as they may contain large unacceptable errors.

New Data on the Mineralogy of Chromite from the Nuggihalli Schist Belt,Western Dharwar Craton,Karnataka,India:Petrogenetic Implications

The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt （NSB） in the western Dharwar craton, Karnataka, South India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NSB. Petrography and ore microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The ferritchromite compositions are characterized by higher Cr number （Cr/[Cr＋AI]） （0.68-0.98） and lower Mg number （Mg/[Mg＋Fe]） （0.33-0.82） ratios in ferritchromite compared to that of parent chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg, AI, Cr, and Fe between the chromite, surrounding silicates （serpentines, chlorites）, and fluid during serpentinization.

Differential Evolution of High-Pressure and Ultrahigh-Pressure Metapelites from Habutengsu, Chinese Western Tianshan: Phase Equilibria Modelling and ^(40)Ar/^(39)Ar Geochronology

Metapelite is one of the predominant rock types in the high-pressure–ultrahigh-pressure（HP–UHP） metamorphic belt of western Tianshan, NW China; however, the spatial and temporal variations of this belt during metamorphism are poorly understood. In this study, we present comparative petrological studies and 40^Ar/39 ^Ar geochronology of HP and UHP pelitic schist exposed along the Habutengsu valley. The schist mainly comprises quartz, white mica, garnet, albite and bluish amphibole. In the Mn O–Na2O–Ca O–K2O–Fe O–Mg O–Al2O3–Si O2–H2O（Mn NCKFMASH） system, P–T pseudosections were constructed using THERMOCALC 333 for two representative pelitic schists. The results demonstrate that there was a break in the peak metamorphic pressures in the Habutengsu area. The northern schist has experienced UHP metamorphism, consistent with the presence of coesite in the same section, while the southern one formed at lower pressures that stabilized the quartz. This result supports the previous finding of a metamorphic gradient through the HP–UHP metamorphic belt of the Chinese western Tianshan by the authors. Additionally, phengite in the northern schist was modelled as having a Si content of 3.55–3.70（a.p.f.u.） at the peak stage, a value much higher than that of oriented matrix phengite（Si content 3.32–3.38 a.p.f.u.）. This indicates that the phengite flakes in the UHP schist were subjected to recrystallization during exhumation, which is consistent with the presence of phengite aggregates surrounding garnet porphyroblast. The 40^Ar/39^ Ar age spectra of white mica（dominantly phengite） from the two schists exhibit similar plateau ages of ca. 315 Ma, which is interpreted as the timing of a tectonometamorphic event that occurred during the exhumation of the HP–UHP metamorphic belt of the Chinese western Tianshan.

Dynamic response characteristics of dry and watersaturated schist under impact loading

Many geological engineering hazards are closely related to the dynamic mechanical properties of rock materials.However,most existing studies on the dynamic mechanical properties of rock materials were conducted on the hard rocks such as sandstone,granite,limestone,and marble,whereas soft rocks,such as schist,are less studied.Therefore,in this study,a series of triaxial impact tests were conducted on dry and saturated schist by employing a modified triaxial split Hopkinson pressure bar system to reveal the coupling effects of water,strain rate,and triaxial confining pressure on the mechanical properties of schist.The results show that schist is a type of watersensitive rock and the stress-strain curve of saturated schist has apparent ductility.The effects of strain rate on dynamic strain,deformation modulus and peak stress were analyzed.The results also show that the dynamic peak stress is affected by the combined softening effect and viscous effect of water under impact loading.Finally,it was found that the failure mode of schist belongs to typical axial tensile failure under uniaxial impact tests,and shear failure is the main failure mode under triaxial impact tests.With the increase in confining pressure,the failure modes of schist change from tensile failure to shear failure.This research can provide useful parameters for geological engineering hazard prevention in mountain areas.

Metamorphism of the Basement of the Qilian Fold Belt in the Minhe-Ledu Area, Qinghai Province, NW China

The basement of the central Qilian fold belt exposed along the Minhe-Ledu highway consists of psammitic schists, metabasitic rocks, and crystalline limestone. Migmatitic rocks occur sporadically among psammitic schist and metabasitic rocks. The mineral assemblage of psammitic schist is muscovite + biotite + feldspar + quartz ± tourmaline ± titanite ± sillimanite and that of metabasitic rocks is amphibole + plagioclase + biotite ± apatite ± magnetite ± pyroxene ± garnet ± quartz. The migmatitic rock consists of leucosome and restite of various volume proportions; the former consists of muscovite + alkaline feldspar + quartz ± garnet ± plagioclase while the latter is either fragments of psammitic schist or those of metabasitic rock. The crystalline limestone consists of calcite that has been partly replaced by olivine. The olivine was subsequently altered to serpentine. Weak deformations as indicated by cleavages and fractures were imposed prominently on the psammitic schists, occasionally on metabasitic rocks, but not on migmatitic rocks. The basement experienced metamorphism up to temperature 606-778± and pressure 4.8-6.1 kbar (0.48-0.61 GPa), equivalent to amphibolite-granulite facies. The peak of the metamorphism is marked by a migmatization which occurred at several localities along the studied route 587-535 Ma ago. The basement also recorded a retrograde metamorphism of greenschist facies, during which biotite, garnet, amphibole, and pyroxene were partly altered to chlorite.

Tectonic Setting of the Kadiri Schist Belt, Andhra Pradesh, India

Plate tectonic activity has played a critical role in the development of petrotectonic associations in the Kadiri schist belt. The calc alkaline association of basalt, andesite, dacite and rhyolite （BADR） is the signature volcanic rock suite of the convergent margin. The N-S belt has gone below the unconformity plane of Cuddapah sediments. In the northern part geochemical and structural attributes of the Kadiri greenstone belt is studied along with microscopic observations of selected samples. Harker diagram plots of major elements generally indicate a liquid line of descent from a common source, such that BADR rocks are derived from a common parent magma of basaltic to andesitic composition. These calc-alkaline volcanic rocks are formed at convergent margins where more silicic rocks represent more highly fractionated melt. All the litho-units of this greenstone belt indicate crush and strain effects. The stretched pebbles in the deformed volcanic matrix with tectonite development along with associated greenschist facies metamorphism, alteration and hydration is remarkable. Flow foliation plane with N-S strike and very low angle （5~ to 10~） easterly dip and N-S axial planar schistosity formed due to later phase isoclinal folding can be clearly identified in the field. Basic intrusives are quite common in the surrounding area. All the observations including the field setting and geochemistry clearly demonstrate ocean-continent subduction as the tectonic environment of the study area.

Peraluminous A-type granites formed through synchronous fractionation,magma mixing,mingling,and undercooling:evidence from microgranular enclaves and host Mesoproterozoic Kanigiri granite pluton,Nellore Schist Belt,southeast India

The field and microstructural features coupled with mineral chemical data from microgranular enclave(ME)and host Mesoproterozoic Kanigiri granite(KG)pluton of Nellore Schist Belt(NSB),Southeastern India,have been documented in order to infer the likely processes responsible for the origin and evolution of ME and host KG magma.The ME and host KG bear the same mineral assemblages barring the KG which does not contain amphibole;however,they are modally disequilibrated.The ME in KG is originated due to multiple intrusions of ME magmas into the crystallizing host KG magma chamber.Field and textural features indicate the dynamic magma flow,mingling,and undercooling of the ME against a relatively cooler surface of host KG magma.The presence of NSB country rock xenoliths and its diffuse boundaries suggest the intrusive relation and marginal assimilation by the intruding KG magma.The occasional cumulate texture in the ME appears to have formed by the accumulation of early-formed minerals that crystallized rapidly in the ME magma globules.The ME shows the magmatically deform features developed due to the flowage and erosion by the subsequent intrusions of ME magma pulses into the crystallizing host KG magma chamber.The ME amphiboles show unusual composition as ferro-edenitic hornblende to potassian-hastingsitic hornblende,that crystallized in the subalkaline-alkaline transition,low fO_(2)(reducing to mildly oxidizing)magma.The unusual extremely low Mg/Mg+Fe^(t)=0.015(avg.)of ME amphiboles may be related to the changing physico-chemical(P,T,fO_(2),and H_(2)O)condition of the ME magma or they might have crystallized in equilibrium with more evolved KG magma.The KG(FeOt/MgO=37.04,avg.)and ME(FeO~t/MgO=77.72,avg.)biotites are siderophyllite,and buffered between QFM and NNO syn-crystallizing in the water undersaturated(H_(2O)≈3.58 wt.%in KG;≈3.53wt.%in ME),alkaline anorogenic(A-type)host magmas that were emplaced at mid-crustal(4–5 kbar;17 km)depth.Field,microtextural and mineral chemical evidences suggest that the alkaline KG magma originated from crustal source and evolved through synchronous fractionation,mixing,and mingling with coeval ME magmas in the KG magma chamber.

Trace Elemental Expression in Soil Substratum and Floral Species in Selected Lateritic Profiles in the Northern Part of Kolar Schist Belt, Dharwar Craton, India

Extensive laterite cappings are observed in the northern part of Kolar schist belt and they are underlain by pillowed metabasalt and partially weathered auriferous cherty intercalations. To appraise the possible distribution of trace elements in both laterite cappings and in plants growing over there, a geobotanical study was conducted in the well exposed, almost flat to slightly undulating lateritic profiles in Jaderi-Holur-Nayakarahalli stretch in the northern part of Kolar schist belt. Due to humus-poor lateritic soil and scanty rainfall, the vegetation is sparse and scrubby. Shrub species are relatively more abundant than herbs and trees. The shrub species studied are Argyreia cuneata, Dodonaea viscosa, Carissa carandas, Ziziphus species, Barleria buxifolia and Atylosia scarbiocides. The herb species are mainly represented by Leucas ciliata, Pulicaria wightiana, Hyptis suaveolens, Tephrosia tinctoria, Trichodesma indicum, Stylosanthes fruticosa, Evolvulus alsinoides, Pavonia zeylanica, Orthosiphon diffusus, Waltheria indica and Stachytarpheta indica. Less frequent species included Acacia megaladena and Dolichandrone atrovirens. Geochemical analysis of different plant species and lateritic soil samples has been carried out. Cu, Cr, Zn, Ni, Co, As, Mn and Mg are in good concentration in soil but the same are impoverished in the plant species except Mn. A few analyses for Au show that its values are close to background concentration. However, plant uptake of Au appears to be better (25 - 86 ppb). The humic acid activity could have enabled gold to get absorbed by plants. While all other analyzed metals show higher range of concentration in soil compared to flora, gold shows a reverse relationship.

Shear-Controlled Gold Mineralization of G. R. Halli Area of Chitradurga Schist Belt, Dharwar Craton: Insights from Fluid Inclusion Study

Gold mineralization at G. R. Halli is located along the Central shear zone of Chitradurga schist belt, extending from west of Gonur, through east of G. R. Halli and C. K. Halli to east of Honnemardi, roughly parallel to stratigraphic units. The NNW-SSE trending shear zone has a width of 0.5 to 1.5 km shows extensive carbonatization of metabasalts and the associated lithologies confined to NNW-WNW trending arcuate brittle-ductile zone. The sheared and silicified contact zones between carbonaceous argillite and schistose metabasalt form the potential sites for localization of mineralization. The gold is associated with sulphides mainly pyrite, arsenopyrite, galena, sphalerite, minor chalcopyrite. Textural relationship indicates two stage sulphide mineral assemblages co-relatable with two stage fluid ascents having temperature of homogenization between 125°C and 256°C. It is a typical epigenetic lode gold system, which got affected by later deformation.

Metasediments in the Alahina Sector and Associated Mineralization (North-Eastern Guinea)

The Alahina sector is located in the North-East of Guinea, precisely in the Siguiri volcano-sedimentary basin. It consists mainly of meta-sediments traversed by Paleoproterozoic pyroclastite, granite, monzogranite and granodiorite veins as well as Mesozoic dolerite and gabbros veins. This article presents new data, on the one hand, on the geochemical petrographic features and the origin of the metasediments of this zone, and on the other hand, on the genetic model of the gold mineralization that they contain. Field observations, as well as petrographic and geochemical studies reveal that the meta-sediments consist of sericite and chlorite schists. They belong to the groups of shales and grauwackes. Their protholites are moderately altered (60 N/YbN = 6.31 - 13.24) and a flat heavy rare earth patterns (HREE). This spectrum is almost identical to those of the “Post-Archean average Australian Shale” and Early Proterozoic Greywackes. Two types of polyphase gold mineralization occur in the Alahina sector: disseminated and veined. They consist of particular of grains and nanoparticles pyrite associated with gold, magnetite, hematite, ilmenite. The hydrothermal alteration accompanying this mineralization consists of silica, microcline, chlorite-epidote-sericite-carbonates.

Compositional Features and Industrial Assessment of Talcose Rocks of Itagunmodi-Igun Area, Southwestern Nigeria

Talcose rocks from Itagunmodi and Igun areas within the Ilesa Schist Belt, southwestern Nigeria, were studied to determine their compositional affinities and industrial properties. The talcose bodies occurred as lensoid enclaves closely associated with amphibolites and quartz-mica schist. Petrographic and X-ray diffraction-aided mineralogical studies reveal that the talcose rocks are of the talc-chlorite schist variety composed predominantly of talc (average 73.63%), subordinate chlorite (average 16.08%) and accessory lizardite (average 6.5%). Total whole rock characterization of the samples using Lithium Fusion digestion revealed high mean concentrations of SiO2 (57.53%), MgO (24.84%) and Fe2O3 (7.73%) with significant enrichment of Ni, Co and Cr;and low values of Ba, Rb, Sr, V, Cu and Pb. The talc-chlorite schists plotted in the peridotitic komatiite field of the Al2O3-(FeO + TiO2)-MgO diagram. Water Absorption Capacity ranges from 6.25% - 8.20%, Loss on Ignition is 4.8% - 6.1% while Linear Shrinkage is 1.25% - 1.70% and firing colour is brown to dark-brown. The overall compositional features of the talcose rocks of the area, which were hitherto uncharacterized, show their suitability as raw materials for paint, coloured pottery, ceramic insulation, textile, rubber and plastic manufacture with varying beneficiation requirements. Their high trace element content however, makes them unsuitable for use in pharmaceutical and cosmetic applications.

Petrological Characteristics of the Peddavura Schist Belt and Adjacent Rocks in Eastern Dharwar Craton in Parts of Nalgonda District, Telangana State

The Peddavura greenstone Linear Belt, NW-SE trending, is formed in the Eastern part of the Dharwar Craton of south India, extended over 62.5 sq•km in Nalgonda and Guntur districts region. The entire belt is illustrated as Peninsular Gneiss. The Belt Study has attracted geologists for conducting further research to evaluate the crust forming process at the time of early volcanic eruption of Earth’s history. The South Indian Dharwar Craton depicts and exposes the crustal segments where geological activities took place consistently during the Precambrian. The PSB (Peddavura Schist Belt) mostly consists of meta volcanic (meta basalts), amphibolites, granites, dolerites, basaltic andesites, pegmatite and Banded Magnetite Quartzite’s (BMQ) rock types. The 20 represented rock samples made for thin section studies. Based on the Petrological studies minerals are showing uralitization, saussuritization in the granite with mylonite structures, perthite and dolerite are showing heavy metal such as rutile and other opaque minerals (Magnetite, hematite, and typical pyrite crystal) are present in different represented rock samples. The minerals are showing different alteration zones along with microstructures. Using the Petrological studies the minerals and rock types are identified in the study region.

Structural Control of Ore Mineralization in the Southeastern Margin of Western Nigeria Basement

Structural analyses are often ignored in mineral prospecting endeavor of any geological terrain despite the importance of geological structures in the formation of ore deposits. This paper correlates the results of mineral prospecting campaign to those of the structural analysis in the southeastern margin of the western Nigeria basement. The mineral prospecting was executed by essentially geochemical-exploration methods, while the structural analysis was achieved by lineament analysis using Landsat-8 imagery. The mineral prospecting campaign eventually led to the discovery of gold bearing marble deposit in the Dagbala area;silver and copper bearing silicified sheared rock in the Dagbala, Ojirami, Erurhu and Atte areas;lead and zinc bearing metaconglomerate around Egbigele;uranium and thorium bearing pegmatite in the Dagbala area. The Landsat-8 lineament analysis showed the presence of a shear zone in the central, folds in the SW, and fractures in the NE parts of the study area. The relation between the two is such that the gold and silver-copper mineralization is associated with the shear zone, the lead-zinc mineralization to the folds, and the uranium-thorium mineralization to the fractures. Indeed, geological structures guide mineralization and their analysis can be employed for mineral prospecting.

Geochemical Orientation Study of Stream Sediment Samples in the Southern Part of Nuggihalli Schist Belt: Ore Mineral Phases and Their Implications on the Bedrock Potential for Ores

Stream sediment sampling is a significant tool in geochemical exploration. The stream sediment composition reflects the bedrock geology, overburden cover, and metalliferous mineralization. This research article focuses on assessing selected trace element concentrations in stream sediments and interpreting their inter-element relationships using multivariate statistical methods. Tagadur Ranganathaswamy Gudda and its surroundings in the Nuggihalli schist belt of southern India have been investigated in the present work. The geology of the study area is complex, with a diverse range of litho units and evidence of strong structural deformation. The area is known for its mineralization potential for chromite, vanadiferous titanomagnetite, and sulfides. The topography of the region is characterized by an undulating terrain with a radial drainage pattern. Most part of the schist belt is soil covered except the Tagadur Ranganathaswamy Gudda area. For this study, a discrete stream sediment sampling method was adopted to collect the samples. Stream sediment samples were collected using a discrete sampling method and analyzed for trace elements using an ICP-AES spectrophotometer: Fe, Cr, Ti, V, Cu, Ni, Zn, Pb, Mn, Cd, and As have been analyzed. The analytical data were statistically treated using the SPSS software, including descriptive statistics, normalization of data using natural log transformation, and factor analysis with varimax rotation. The transformed data showed a log-normal distribution, indicating the presence of geochemical anomalies. The results of the study provide valuable insights into the geochemical processes and mineralization potential of the study area. The statistical analysis helps in understanding the inter-element relationships and identifying element groups and their implications on bedrock potential mineralization. Additionally, spatial analysis using inverse distance weighting interpolation provides information about the distribution of geochemical parameters across the study area. Overall, this research contributes to the understanding of stream sediment geochemistry and its application in mineral exploration. The findings have implications for future exploration efforts and can aid in the identification of potential ore deposits in the Nuggihalli schist belt and similar geological settings.

Comparative Geochemical and Petrographic Studies of the Various Granitoids between Central and Western Arm, in the Central Part of Ramagiri Schist Belt and Their Petrogenetic Histories

Granitoids between the central and western arm of Ramagiri schist belt in its central part, are broadly classified into the migmatite gneiss, grey granodiorite and pink monzogranite, based on field characteristics and petrographic features. These granitoids belong to the Tonalite-Granodiorite-Monzogranite (TGM) suite of PGC-II. All the samples are fresh as per the CIA values, PC1-PC2 binary plot and MFW ternary plot. The granodiorites occupy the expected field in the normative IUGS, TAS, and R1-R2 classification diagrams, but the monzogranites occupy the monzogranite field in the normative IUGS classification diagram and granite to alkali granite field in the rest. The granodiorites exhibit both ferroan to magnesian, alkali-calcic nature with metaluminous I type features and falls in the calc-alkaline to high K calc-alkaline series. They have high ΣREE (an average 327.905 ppm) content, and show LREE enrichment ((La/Sm)N = 3.1 - 6.8) with enriched but relatively flat HREE ((Gd/Yb)N = 1.75 - 5.26) patterns and weak negative to positive Eu anomaly (Eu/Eu* = 0.62 - 1.18). The monzogranites, on the other hand, are peraluminous, alkalic, ferroan, high K calc-alkaline, S-type granites, exhibiting relatively low ΣREE (an average 118.693 ppm) contents, strongly fractionated REE patterns with highly enriched LREE ((La/Sm)N =1.74 - 9.76), depleted HREE ((Gd/Yb)N = 0.43 - 2.21) patterns having concave upward shape, and strong negative Eu anomaly (Eu/Eu* = 0.23 - 0.89). Geothermobarometry revealed the average emplacement temperature and pressure of the granodiorites and monzogranites as 812.5℃, 8.14 ± 0.6 kbar and 775℃, 3.14 kbar, respectively. Based, on the observations, it can be concluded that the granodiorites have formed in volcanic arc setting by partial melting of the lower crust and S-type monzogranites have been produced at a relatively shallower depth in the crust, by continental crust recycling due to hydrothermal influx.

The Discovery and Geological Feature of Kyanite-Topazite in High-Pressure Belt From Central China

For the first time, we find kyanite-topazite which is similar to the white schist from abroad, in aiangsu, Anhui, Henan of China. Because of intercontinental obduction and collision, the kyanite-topazite is formed from the superhigh-pressure metamorphism of sedimentary rock in continental crust, at the depth of mantle. Kyanite-topazite runs parallel to blue schist, eclogite and constitutes the high-pressure metamorphic belt in Central China. Its original rocks are a set of sedimentary rock series which is mainly composed of marginal shallow marine facies to continental facies pelitic to magnesium carbonatite, both rocks exist in Precambrian Middle-Upper Proterozoic metamorphic strata.