Schist Belt Research Articles

Sn-Ta-Nb mineralization potential of pegmatitic bodies in Bunu area, part of Kabba-Lokoja-Igarra Schist Belt, SW Nigeria

The Bunu area in Southwestern Nigeria lies within the Basement Complex that forms part of the Pan-African platform of the crystalline rocks. The complex lies within the vast Trans-Saharan Pan African mobile of Neoproterozoic. The belt is characterized by voluminous post-collision granitoid plutons that are well exposed around the study area. The Bunu area consist of two major lithologic suites namely: (i) the gneiss-schist suite which comprised of Migmatized-gniess/ Migmatized Schist and quartz/mica schist with interbedded amphibolites (ii) intrusive suite that include fine-medium grained granite, medium-coarsed grained granodiorite and porphyritic granite and the minor intrusions like pegmatite, aplite, dolerite and quartz veins. Pegmatite outcrops in the Bunu area of the Kabba-Lokoja-Igarra Schist belt belong to the rare-element type and are mined for columbite-tantalite and gem tourmaline. Pegmatitic textures are well developed, these include large K-feldspar (comb textures), layering and graphic intergrowth of K-feldspar + albite + quartz + schorl and linearly arranged garnet crystals that may be developed at deeper levels of the dyke. Ductile and brittle structural features mapped in the area from remotely sensed and field data are generally consistent with the N-S and NE-SW regional orientation associated with Pan-African event and with minor axes of NNW-SSE and E-W planar structures. Trace elements geochemistry of the pegmatite (bulk rock and mineral extracts of K-feldspars and Mica) revealed that Rb, Sr, Ba, Li and Cs are enhanced in the Otafun and Okutose pegmatites indicating higher fractionation levels. Also, the rare-metals Nb, Ta and Sn were also enriched in the most evolved Otafun and Okutose pegmatites. Trace-element variations in mica from the pegmatites indicate that they are per-aluminous LCT (lithium, cesium, and tantalum) family and bery-columbite subtype. The origin of the gradual composition variation trend observed from the host granite bodies to the pegmatites reflects the increasingly fractionated melt composition and systematic enrichment of the incompatible trace elements Li, Rb, Cs, Be, Na, Ta and Sn. The Zr-SiO2 and Sr-Rb plots of the pegmatite bulk rock samples suggest that they are genetically magmatic and poorly differentiated with little or no post-magmatic metasomatism. Ta vs Cs and Ta vs Ga plots for the chemistry of K-feldspar and muscovite mineral extracts from the pegmatites in Bunu area show potential for tantalum and niobium (>75 ppm) mineralization, thus implying that the mineralization in these pegmatites is probable, therefore investors should use caution.

Mineralisation potential assessment using analytical hierarchy process (AHP) modeling technique: A case study of Ilesha schist belt, southwestern Nigeria

A mineralisation potential assessment in part of Ilesha Schist belt of southwestern Nigeria was carried out using multi criteria decision analysis (MCDA) in the context of analytical hierarchy process (AHP). Three parameters sourced from aeromagnetic, electrical resistivity and geological data were identified to favour gold mineralisation in the study area. These parameters include lineament density (Ld), lithology (Lt), and electrically derived coefficient of anisotropy (An). The application of data enhancement techniques such as total horizontal derivative, 3-D Euler deconvolution and source edge detection were employed in the production of lineament map of the study area. Two hundred and sixty-five (265) vertical electrical sounding (VES) points were investigated using Schlumberger configuration. Coefficient of anisotropy derived from the Dar-Zarouk parameters was obtained from the synthesized VES data. The lithologic information was obtained from the existing geological map of the area. The orientations of lineaments displayed on the aeromagnetic results suggest predominantly NE-SW trending structures, which are characteristic of the Pan African orogenic events in the area. However, few of the E-W trending lineaments are imprints of secondary structural alteration. Furthermore, the Euler deconvolution solutions revealed that the area is characterised by geological contacts with estimated depth of 94–600 m. The coefficient of anisotropy results obtained from the geo-electric parameters vary from 1.00–2.87. AHP weighting and ranking technique was used to develop a reliable mineralisation potential model (MPM). In line with the recommended lower limit of 10 %, the consistency ratio of the developed model is 9.61 %. The produced MPM was classified into low, moderate and high mineralisation potential zones. Preliminary validation of the MPM using the existing pits in the area showed 79 % success rate. The validation of the model using the existing geochemical information from the previous studies indicated 85 % agreement with the conceptual model; thus, confirming the reliability of the produced MPM. The developed model is therefore believed to serve as a future reference in the resource management of the study area.

Integrated geophysical investigation of the mode of occurrence of mineralisation in part of Ilesha Schist Belt, Southwestern Nigeria

Integrated geophysical investigation of the mode of occurrence of mineralisation in part of Ilesha Schist Belt, Southwestern Nigeria

New insights on the Ife-Ilesha schist belt using integrated satellite, aeromagnetic and radiometric data

The present study combined analysis of satellite, aeromagnetic and radiometric data for evaluation of structural features within the Ife-Ilesha schist belt. Shuttle Radar Topographic Mission digital elevation data have been enhanced using hill-shading technique for the delineation of morphological features. The superposition of total gradient amplitude lineaments on the 3-D Euler deconvolution map revealed the trends and depth of structural features within the study region. The major trends are NE–SW, NNE–SSW, E–W and minor trends in the N–S direction, including the Ifewara shear zone that trends in the NNE–SSW. The estimated depths to the top of the sources within the shear zone varies from 90 to 200 m. Complementary analysis of the airborne radiometric data revealed that the Ifewara shear zone and adjacent regions are characterized by radiometric anomalies, indicating regional mineralization alteration zone. Generally, there is a good correlation between the satellite, radiometric, aeromagnetic maps which provides new insights and re-evaluation of structural features.

Petrography and geochemistry of the granitoids and associated volcanic rocks of the northern part of Kushaka and Birnin Gwari schist belts, NW Nigeria: implications for provenance and geological setting

The granitoids and the associated volcanic rocks of the northern part of Kushaka and Birnin Gwari schist belts were emplaced in the ca. 3.5 – 1. 0 Ga remobilized basement complex terrain composed of metasedimentary and metaigneous rocks that later underwent medium- to high-grade metamorphism during the Pan-African thermo-tectonic event. They comprise dominantly of diorite, granodiorite, granite, granite gneiss and basalt, and are product of metasomatism and injections. The diorite and granodiorite occur as paleosome and the granite as leucosome with the development of high temperature minerals, locally attaining granulite facie metamorphism. Plagioclase, biotite, hornblende, pyroxene and olivine fractionation played an important role during their genesis through fractional crystallization of basaltic magma and partial melting of older dioritic-granodioritic source rock in the deep crust which were themselves ultimately derived through fusion of mantle materials contaminated by continental crust and enriched by fluids derived from oceanic crust in an arc setting. Geochemical characteristics have revealed different chemical trends in granitoids and basalts. The granitoids are calc-alkaline, ferroan and magnesian, metaluminous and peraluminous in character. They also exhibit I- and S-type signatures with enrichment in LILE, radioelements (Th and U), depletion in Nb, Sr, P and Ti, high LREE fractionation factors (La/Yb) (1.05 to 77.20), and pronounced negative Eu anomalies (Eu/Eu* = 0.34 to 1.10). Similar patterns of spidergrams show that the rocks are genetically related and were emplaced in a volcanic arc and syn-collisional setting. The basalt is tholeiitic, metaluminous and high in Fe and Mg with relative enrichment in LILE, HFSE, low and near flat LREE and HREE, low fractionation [(La/Yb)N = 1.4] with Eu/Eu* value of 1.10. It is evidently a back arc cum mid-ocean ridge (MORB) basalt. The consistent decrease in the content of MgO, Fe2O3 MnO, CaO, Sc, Cr and V of the basalt, diorites, granodiorites, and granites indicates continuous igneous crystallization process. It seems that extrusion of basaltic magmas from the sub-circular Kushaka Complex derived from subduction of oceanic crust resulted in complete change in the genesis of the magmas at the time, in this region. The granitoids and the basalt may have formed behind subducted Pan-African plate due to effects of compressional and tensional forces caused by oceanic plate roll-back which resulted to a zone of extension, parallel to the island arc. The granitoids present similar chemical characteristics to those in the other areas underlain by the basement complex and schist belts in the north and eastern parts of the Pan-African mobile belt, while basalts are similar to ophiolites and amphibolites in other schist belts of Nigeria forming a lateral continuation of the same mobile belt.Â

Tectonic divisions and accretionary model within Dharwar Craton: New insights from gravity surveys on status of Chitradurga Schist Belt

Tectonic divisions and accretionary model within Dharwar Craton: New insights from gravity surveys on status of Chitradurga Schist Belt

Geochemistry and Petrogenetic Features of Metasediments in Northern Part of Kushaka and Birnin Gwari Schist Belts NW Nigeria

The Kushaka and Birnin Gwari metasediments and associated banded iron formations constitute important lithological units within the Precambrian Basement Complex. They were studied to evaluate their compositional characteristics and petrogenesis in order to contribute further to the understanding of the geodynamic evolution of Nigeria’s Schist belts. The Kushaka metasediments comprise quartzite, graphite and sulphur bearing staurolite-muscovite quartz schist interbedded with Banded Iron Formations (BIFs) while the Birnin Gwari schist comprise staurolite-biotite quartz schists with lithic (angular to rounded clastic quartz, schistose, volcanic and quartzo-feldspathic) sandstones. These schists are associated with fissile and ferruginous quartzite, banded and granitic gneisses, basalts and amphibolites. Petrographic work revealed varying proportions of quartz, staurolite, biotite and muscovite with subordinate iron-oxide minerals. Geochemically the metasediments in the Kushaka are enriched in SiO 2 (61.23 to 65.99 wt %) with elevated values of Al 2 O 3 (16.53 – 20.93 wt %), Ba, V, W, La, Nb, Nd, Rb, Th and Zr; while the Birnin Gwari schists, even though enriched in SiO 2 (63.03 to 65.13 wt %), has moderately elevated Al 2 O 3 (15.4 – 15.16 wt %) values but is depleted these trace elements. Field and geochemical characterization of the Kushaka metasediments suggests peraluminous, tholeiite and calc-alkaline character; arkosic and shale-greywacke sedimentary protoliths derived from quartzose sedimentary and granite-quartz monzonite provenance. Calculated ICV values of 0.52 - 0.99 and occurrences of graphite and sulphur in the Kushaka metasediment suggests shallow stable shelf-type sediment of carbonate and iron formations in a reducing environment with matured sedimentary protolith. The Birnin Gwari metasediments on the other hand have a peraluminous and calc-alkaline character, inherited from shale-greywacke and quartzose sedimentary protoliths derived from granodioritic and granite-quartz monzonite provenance. ICV values of 1.12 – 1.18 and angular and volcanic clasts suggest rapid subsidence of basin during genesis and / or tectonic instability in the surrounding environment with immature sedimentary protolith. This is an indication of two contrasting environment in an arc setting with contribution from basaltic and andesitic detritus. Available geochronological data on granite and granitic gneisses have ascribed the Kushaka schist belt to Kibaran and the Birnin Gwari schist belt a Pan-African age. Keywords : Metasediments, protolith, Kushaka, Birnin Gwari, quartzite, provenance, shale, greywacke. DOI: 10.7176/JEES/11-16-05 Publication date: June 30 th 2021

Field Occurrence, Petrography and Structural Characteristics of the Basement Rocks in the Northern Part of Kushaka and Birnin Gwari Schist Belts, Northwestern Nigeria

Field, studies and geological mapping on a scale of 1:50000 were carried out to determine the lithologic framework and structural features of the Basement Complex rocks in northern parts of the Kushaka and Birnin Gwari schist belts (Kushaka Sheet 122). The area is underlain predominantly by five main rock types mainly (i) Migmatite-Gneiss-Quartzite suite comprising dioritic, granodioritic and granitic gneisses with fissile and ferruginous quartzites and banded iron formations (BIF); (ii) Kushaka graphite and sulphur bearing biotite and muscovite quartz schist inter-banded in places with iron formations; (iii) Birnin Gwari biotite-staurolite quartz schist; iv) the Kushaka Gneiss Complex composed of basalts (which is being reported for the first time), staurolite and muscovite gneisses and banded iron formations (BIF), and (v) syn-tectonic and late-orogenic biotite-hornblende syenite (BHS) and biotite-hornblende granite (BHG) in the Kushaka schist belt and biotite muscovite granite (BMG) in the Birnin Gwari schist belt area. Petrographic studies have revealed that essential minerals are quartz, K-feldspars (orthoclase, microcline), plagioclase, pyroxene, epidote, hornblende, biotite and muscovite while the accessory minerals are titanite, zircon, apatite, iron oxide (magnetite and hematite). With pyroxenes occurring in the dioritic and granodioritic rocks, metamorphism may have locally reached grannulite facies. Imprints of Pan-African thermo-tectonic events have shown observable migmatization as the first thermo-tectonic event resulting in plastic deformation D 1 and regional S 1 foliation, demostrated by presence of tight isoclinals fold, compositional banding and N – S preferred orientation of mafic minerals. The D 2 deformation is co-axial with D 1 and resulted in the formation of decimeter sized F 2 isoclinal folds, B 2 boudins and eye ball structures that are parallel to S 1 plane schistocity. Strike-slip faults with dextral sense of movements were mapped in a number of places. D 3 deformation is concentrated in the Kushaka Gneiss Complex with near circular deep fractures south of the Kalangai fault. Here granitization and fragmentation of proto-mylonitic staurolite resulted in brittle deformation and F 3 open fold that refolded or transposed the earlier tight isoclinal F 2 folds. The D 4 deformation resulted in N-S and NW-SE quartz veins and pegmatite dykes which serve as channels for epigenetic gold-sulphide and rare metal bearing ore fluids. Keywords: Basement Complex, Pan-African, metamorphism, deformation, Kushaka, Birnin Gwari, Nigeria DOI: 10.7176/JNSR/12-12-02 Publication date: June 30 th 2021

Pan African Nappe system: evidence of thrust structures from Okemesi, southwestern Nigeria

The Okemesi area, southwestern Nigeria, is part of the Ilesha schist belt and play host to the Okemesi fold belt and the Ifewara Shear Zone. Nappe structures had been proposed for some parts of Southwestern Nigeria without very clear meso or micro structural evidence. This study provides a lot of new structural evidences to substantiate the inferred Nappe structures within the Okemesi fold belt. Mapping of the Okemesi fold has been hampered by thick vegetation in the past. However, a major deformation zone was exposed by the recent landslide activities in the area, structures and lithologies exposed by the landslide were studied and structural features that are typical of transtensional and transpressional settings were observed. This paper presents the result of the systematic filed mapping which revealed the complete, fold transposition, elements of internal strain such as cleavages and mineral lineation, intrafolial folds, flexure slip, sheath, recumbent and conjugate kink folds, winged porphyroblast, faults (low angle reverse faults, dextral faults, normal faults), ramp and flat structures, etc. The characteristics and the geometry of the observed thrust structures make it an important piece of evidence, not only to infer the tectonic events in the area, but also to constrain the timing and nature of movement associated with thrusting in the area.

Hyper spectral and Geochemical Signatures Study on Late Archeaen of Indian High Grade Manganese Deposits in Halekal Band of Bhahaddurghatta-Hosahatty Village, Chitradurga Schist Belt (Csb), Karnataka, India

Manganese is one of the most widely distributed elements in the earth’s crust and mapping of these deposit are of high economic interest. Manganese occurs as diverse genetic types that is vital for iron and steel production. It occurs usually in the form of oxide, hydroxide, carbonate and silicate which is an important raw material for iron, steel industry, chief manufacturer of chemicals and dry cells in the form of manganese dioxides. Advanced analysis of hyperspectral signatures and GPS applications have opened a newest approach in exploration and systematic mapping of economic ore deposits. The present study aims to integrate the hyperspectral signatures with major elements of manganese ore deposits of Halekal band in Bhahaddurghatta-Hosahatty village of Chitradurga Schist Belt. The samples collected from field are studied in the laboratory using thin and polished sections under microscope and X-Ray Diffraction (XRD) analysis. Efforts are created to assess the spectral signatures of four representative random ore samples collected and analyzed through ASD Spectro-radiometer instrument operative in Visible and InfraRed (325 to 2500 nm) region with concentration of major elements. This study clearly demonstrated and documented the spectral absorption features of the selected rock samples in the study area mainly depend on the optical and physico-chemical characters of the rock and major elemental composition as well as mineral constituents of the samples.

The Archean Pavas Block in Uruguay: Extension and tectonic evolution based on LA-ICP-MS U–Pb ages and airborne geophysics

The Pavas Block is an Archean/Paleoproterozoic inlier located in the central segment of Uruguay's Precambrian exposition. A new insight initiated due to the acquisition of airborne geophysical data and new U–Pb zircon dating. The correlation of Archean crustal inliers in the amalgamation of the South American Platform is one of the main objectives in the Precambrian geological investigation. Although Ediacaran lateral strike-slip shear zones controlled the Pavas Block, their ultimate boundaries are not clear. Furthermore, a pre-Neoproterozoic metasedimentary succession discordant on this block is often confused with Neoproterozoic ones. Correctly identifying these limits is a necessary task to modify wrong tectono-stratigraphic models. The airborne total count radiometric imaging and the horizontal derivative of the total magnetic field anomaly reduced to the pole at 1000 m elevation led to establishing the Pavas Block's dimensions, based on new structural interpretation. The filtered magnetic anomaly is concordant with the previous Bouguer anomaly indicating a westward virgation of the Pavas Block in the north. This inlier narrows through the Minas city and along the Sarandí del Yí shear zone. The Sierra de Sosa and Sierra Ballena shear zones were confirmed as lateral limits. The total count radiometric map highlights the presence of brittle-fault reactivation. The Archean La China Complex containing zircons from three periods (~3.3–3.1 Ga; 3.0; 2.8–2.7 Ga) is in the Pavas Block's centre. New U–Pb zircon geochronology provided six samples from different metagranitoids that yielded LA-ICPMS U–Pb zircon ages ranging between 3353 ± 9 Ma and 1839 ± 2 Ma. Its southern periphery shows more recent Archean and Orosirian metagranitoids. These rocks were later partially affected by Neoproterozoic deformation. The preservation of igneous textures, field relationships, and zircon textures suggested that younger Neoarchean intrusive granitoids emplaced within the basal granitic gneiss “La China” complex. The pre-Neoproterozoic metasedimentary cover intercalates with Neoproterozoic successions until the southern end of the Pavas Block against the Sarandí del Yí Shear Zone. Finally, one granitoid devoid of Archean inherited zircons yielded a concordant 207Pb/206Pb zircon age of 1999 ± 3 Ma (MSWD = 8.1) interpreted as magmatic crystallisation. This Orosirian K-feldspar granite is likely to set the southern border of the block in a transitional crust. The Pavas Block is limited from the Villa Serrana Block by a schist belt of Mesoproterozoic protoliths, and reports enough information to be interpreted as a suspect terrane.

Delineating and Interpreting the Gold Veins Within Bida and Zungeru Area, Niger State Nigeria, Using Aeromagnetic and Radiometric Data

Abstract Both Airborne Magnetic and Radiometric datasets were employed to interpret the geology and geological structures that serve as host to gold and associated minerals within the Bida and Zungeru, Niger State, Nigeria. An area of 55 by 110km2, contained within the cretaceous sediments of Bida Basin and the meta-sediments of Zungeru-sarkin-pawa schist belt. Data interpretation involve the application of a mathematical algorithm for data enhancing such as, Reduce to the Equator, Analytical signal, First Vertical Derivative, and Centre for Exploration Targeting (CET) to the magnetic data, and Ternary imaging to the radiometric data, with a sole aim of mapping geological structures such as faults fracture folds joints and geological boundaries and possible gold mineralization veins that arise from hydrothermally altered zones. Two major geological units inhibit the study area, the cretaceous sediment, and the meta-sediments, major feature identifies within the Cretaceous sediment are the folds majority of which are located within the contacts. The result of the 1VD display is the vivid picture of the observed structural features such as faults fractures folds’ contacts labeled F1 to F8 both within the high region of magnetic susceptibility (in red) and low regions (in blue) geology contacts (yellow), folds (bold yellow) all across the field. Prominently at the North-Western corner of the study area are sets of linear structure that trend NE-SW, located within the contacts between the mylonites and the amphibolites and the belt-type meta-sediments located around Katakwo, Gindei, Kwange, Gabas and Akusu villages. Equallyworth mentioning are sets of lineament (in blue) trend E-W all across the mid-region of the study area, precisely at the Eastern corner within and below the Federal University of Technology Minna around Kata-eregi, Sabon-Dagan, Kakaki down Minkwoigi, Sunbwagi, Kakagi, Sabon dagga, and Bobo-shiri towns, where the majority of volcanic activities must have been recorded. The airborne radiometric show mobilization of the immobile thorium Th, concentration, and this also indicated hydrothermally altered zones. The increase in potassium concentration and decrease in K/Th relation observed from radiometric interpretation are very pinpointing of hydrothermal activities within the study area. The gold mineralisations are found within this vein and in the adjacent, highly deformed host rock located below the Federal University of Technology Minna Campus. The deformation seems to comprise principally of pebbly schist, amphibolites along fine-grained and magnetite.

Volcano Sedimentary Origin of Archaean Banded Iron Formation of Nellore Schist Belt from Chundi-Malakonda-Ayyavaripalle Area, Prakasam District, Andhra Pradesh and its Petro-chemical Characterization

Abstract Banded iron formations (BIFs) are the most significant source of iron in the world. The present study addresses the petrographic and geochemical characterization of the BIF from Chundi-Malakonda-Ayyavaripalle area in the Nellore schist belt of Prakasam district, Andhra Pradesh, their genesis and iron enrichment processes. Six bands of banded magnetite quartzite (BMQ) of Archaean age occur in the area. Field investigations and petrography revealed that the studied BIF samples are hard, compact, weathered and composed of alternate layers of magnetite/martite and subordinate quartz, biotite and muscovite. The BIFs occur in three associations: volcanic (Band 1,3,4,5), sedimentary (Band 6) and volcano-sedimentary (Band 2). The geochemical composition of the whole rock reveals that iron and silica represent 78.48% to 91.74% of the average composition. The total iron (TFe) contents range from 16.25 to 61.80 wt % (average of 38.47 wt %) and is consistent with low-grade siliceous BIF by global standards. All BIFs have high SiO2/Al2O3, Fe/Ti, and low Al/(Al+Fe+Mn), which suggest a mixed hydrogenous and hydrothermal origins. Geochemical results for the BIFs lead to the conclusion that all the BIFs are of Algoma-type with Precambrian affinity and formed in small sloped or terraced silled basins in the back-arc areas with MORB affinity, surrounding an immature island arc. Depending on the degree of replacement and shape of the magnetite crystals, two textural types of magnetite (Magnetite-I and Magnetite-II) are observed. Ore formation occurs in three stages: Magnetite (protore), Martites and Martite-goethites.

Structural mapping and gold mineralisation potential evaluation from airborne time – domain electromagnetic (TDEM) data of Ilesha Schist Belt, southwestern Nigeria

The airborne Time-domain electromagnetic data acquired over the Ilesha Schist Belt in southwestern Nigeria were filtered, enhanced and analysed to generate ground conductivity responses at different time gates and employed to characterise the subsurface in terms of rock distribution, structural framework as well as evaluate the gold and base metal mineralisation potential of the region. The near-surface sensitive early time gate conductivity responses (EMZ1 – EMZ3) indicate relatively high subsurface conductivity distribution (60–120 mS/m) in amphibole schist and pegmatite terrain in the west while medium to low-conductivity (<5 mS/m) values were recorded in the east underlain by granitic rocks. Major and minor linear/sub-linear conductive features having conductivity in excess of 2 mS/m and trending NE-SW, NNE-SSW, NNW-SSE and ENE-WSW directions were delineated on the mid conductivity time gate responses (EMZ3 – EMZ5). One of which presents geometry and pattern consistent with the well-reported Ifewara – Iwaraja fault system that runs through the entire Ilesha Schist Belt. Very high anomalous conductivity (160–300 mS/m) responses at late conductivity time gates (EMZ10 – EMZ13) with characteristic long decay curves were obtained over isolated zones, especially along fractures and veins suggesting the occurrence of structurally controlled gold and base metal mineralisation.

Series of 1-D ER and IP traverses reveal vestige of regional geological structure

At the Basement Complex geological province of central Nigeria, in the state of Niger, just northeast of the Bida Sedimentary Basin, there is the character of non-complexity and high uniformity in the local geology over an appreciable linear spread. This appreciation makes it a standard practice to do one-dimensional vertical electrical sounding surveys in the search for groundwater resources at this area with the expectation of reliable results. This seeming “simplicity” means that intense manual labour can be invested in acquiring a large data-field at a local area of survey where resources are not readily available to do a standard two-dimensional survey of the conventional kind. This is especially significant for the proposed area of development at the Gidan Kwano Campus of the Federal University of Technology, Minna, Thus, with this awareness and the use of the ABEM Terrameter 4000 equipment, the aim of this study was to do an intense acquisition of one-dimensional electrical resistance and concomitant induced polarization programme for this proposed area of development so as to achieve the objective of garnering information about exploitable groundwater locations before structural developments cover these points up. Typical point-to-point one-dimensional tandem electrical resistance and concomitant induced polarisation surveys were completed along east-west profile lines for about 309 survey stations of the available 441 principal locations of the 4 km2 extent of the proposed new development. After due processing and interpretation of the data-field of this survey, whilst remarking that the induced polarisation data-set was used herein as quality control “refiner” only, clusters of reliable groundwater locations were observed at the southwest end of the 4 km2 areal extent of the proposed new development. It conforms to the dip of the landform and comparatively significant overburden-material thicknesses observed over there. Interestingly, in a twist of serendipity, the series of diagonal subsurface “fault-lines” that connect one promising groundwater prospect with the other, describable by a prominent northeast-southwest dip, aligns exactly with the Kazaure-Karaukarau-Kushaka-Ilesha Schist Belt. In the modern geography setting of the present time, the Kazaure-Karaukarau-Kushaka-Ilesha Schist Belt actually traverses a lengthy diagonal across the landscape of Nigeria, cutting through such Nigerian states as Jigawa, Kano, Kaduna, Niger, Kwara, Ekiti, and Osun. There is virtually no surface indicator of this once-prominent schist belt and what this study reveals is its vestigial signature

Application of Morphostructural and Spatial Analyses in Placer-Gold Source Interpretation within Wonaka Schist Belt, Northwestern-Nigeria

Morphologic and placer features were used to characterize, determine the provenance, and transport distances of gold grains within the River Gagare drainage basin of the Wonaka Schist Belt. Field studies, scanning electron examination coupled with energy dispersive spectrometry and binocular microscopy were utilized to study the spatial distributions, shape, size, inclusions, primary and fluvial transport-induced deformations, as well as Cailleux flatness indices. The grains are dominantly subrounded (71%), with the length between 35 – 800 µm and width of 10 – 778 µm while the rounded grains have a mean length of 292.5 µm and width of 179 µm. Similar values for circularity and sphericity are observed in the sub-rounded grains, with slight variations of 2.7 circularity and 2.6 sphericitydistinguished in the rounded grain subset. The Cailleux flatness index range from 2.5 to 9 for subrounded grains and 2 – 15.5 for the rounded, indicating the multisource nature of the grains. The grains are consistent with short to moderate transport distances from the lode sources. The similarities in physical features, lack of delicate secondary growth structures and irregular grain outlines point to a detrital source for the placer deposits. Evidence of emulsion crystallisation type is indicated by the presence of sub- to anhedral inclusions within the Au grains.&#x0D; Keywords: Placer gold, Cailleux flatness indices, Wonaka Schist Belt, Provenance, Northwest Nigeria

Landsat-8 Lineament Analysis for Detection of Epigenetic Mineralization Zones in Parts of Igarra Schist Belt, Southwestern Nigeria

The study of lineaments derived from optical imagery provides insights to the location of mineral deposits as they reflect geologic structures. The present study employs lineament extraction from Landsat-8 Operational Land Imager (OLI) to identify possible areas of epigenetic mineralization in the rocks of Dagbala-Atte District. Fifty-one (51) geologically significant lineaments of varying lengths and directions were extracted. Lineament map revealed three promising zones of epigenetic mineralization. These zones are those in the northeastern, central, and southwestern parts of the district. Previous reconnaissance stream sediment geochemical survey in the larger region comprising the district had selected areas that correlate well with these zones as the more prospective for metallic mineralization. Also, pedogeochemical surveys in the district revealed plausible areas underlain by rocks most likely contain different metallic mineralizations that synchronize well with these promising zones. Geological mapping and preliminary lithogeochemical survey in these zones have unveiled uranium bearing pegmatite in the northeastern zone; gold bearing marble deposit and iron oxide-copper-gold-silver mineralized silicified sheared rock along the central zone; and lead-zinc mineralized metaconglomerate in the southwestern zone. Ample geological studies of these mineralized rocks are recommended.

Tourmaline growth and evolution in S-type granites and pegmatites: constraints from textural, chemical and B-isotopic study from the Gangpur Schist Belt granitoids, eastern India

AbstractAn extensive dataset of major- and trace-element and B-isotope composition related to the compositional variation of the tourmalines from the S-type granite and pegmatite from the Upper Bonai and Gangpur Group granitoids, eastern India, is provided. The Gangpur Schist Belt, consisting of the Upper Bonai and Gangpur Group, lies at the eastern end of the Proterozoic Central Indian Tectonic Zone. An attempt to constrain the source of the boron isotope and describe the magmatic–hydrothermal evolution of the granite–pegmatite system is made. The tourmalines record generally low trace-element concentrations, with the exception of some elements such as Zn, Li, Ga, Mn and Ti. The Zn and Li concentration increases from the tourmalines in the granites to the tourmalines in the pegmatite. Trace-element compositions also vary slightly from the core tourmaline to the rim tourmaline. Tourmalines in granites/pegmatites are mostly Fe-rich schorl, and have S-type B-isotopic signature (δ11B = −10‰ to −12‰). Their chemistries reflect changing salinities of the granitic melts as well as vapour exsolution during progressive crystallization. This study indicates that the tourmalines in the pegmatites crystallized from evolved flux-element-rich (F, B, Li) melt, probably after the crystallization of granite-forming melt.

Neoarchaean Felsic Volcanic Rocks in Tracing Evolution of Arcs: An Insight from Geochemical Data of the Gadag Schist Belt, Western Dharwar Craton

Abstract Quartz porphyry of rhyolitic composition though a volumetrically minor is an important component of metavolcanic successions in the Gadag schist belt in the western Dharwar craton. The quartz porphyries are calc-alkaline, enriched in light rare earth elements (Lan/Ybn ~ 10-20) and with a strong negative Eu anomaly (Eu/Eu*N = 0.45-0.58). These features, coupled with high K2O/Na2O (0.8 to 1.46), low Nb/Th (&amp;lt;1), and Lan/Smn ratios of 4.2 to 6.0, suggest that rhyolitic magma formed from melt generated by partial melting of basaltic crust, subsequently modified by crustal assimilation and crystal fractionation. The geological setting of the quartz porphyries and the geochemical relationships suggest magmatism at a convergent plate tectonic setting. The zircon U-Pb age of 2588.0 ± 2.4 Ma for the quartz porphyry, together with an age of 2732 Ma for similar volcanic rocks in the Chitradurga schist belt further south, and 2614 Ma for felsic volcanics from the Shimoga schist belt, point to an extended period with episodic arc magmatism in the western Dharwar craton of at least ~144myr.

Geochemistry and Petrogenesis of the Banded and Granitic Gneisses in Parts of Kushaka Schist Belt, Northwestern Nigeria

The Kushaka schist belt in the Kwona Mutua and Kushaka areas is one of the 12 well recognized N-S trending belts composed of igneous, metamorphic and metasedimentary rocks in varying proportion. The major rocks of the belt comprise the Migmatite-Gneiss-Quartzite Complex, schists and Pan-African granitoids. Banded and granite gneisses constitute the bulk of the Migmatite-Gneiss-Quartzite Complex. Banded gneiss consists of paleosome and leucosome of dioritic, tonalitic, granodioritic and granitic composition while granite gneiss is composed of biotite, staurolite–biotite and staurolite-muscovite gneiss. Major mineral constituents of these rocks are quartz, orthoclase, plagioclase, pyroxene, biotite, muscovite, orthoclase, microcline and staurolite while the accessory minerals are titanite, apatite and iron oxides. Metamorphism may have reached grannulite facies locally with pyroxenes crystallizing in the dioritic and granodioritic rock. Analysis of geochemical data reveals marked variation in the abundance of SiO 2 (60.77-77.53 wt %), Al 2 O 3 (12.9-15.99 wt %), Fe 2 O 3 (0.78-7.04 wt%), Na 2 O (1.67-5.15 wt%) and K 2 O (1.64-6.13 wt %), typical of rocks of hybrid sedimentary–igneous protoliths. Igneous protolith reveals decreasing P 2 O 5 content with increasing silica content, low K 2 O/ Na 2 O ratio (0.24 – 0.87), low K 2 O values (&lt; 2.5 wt %) displaying mixed tholeiitic and calc-alkaline, metaluminous and peraluminous, ferroan and magnesian character, and high-K calc-alkaline to shoshonitic affinities. By contrast, the rocks of sedimentary protolith shows high K 2 O/ Na 2 O ratio (1.19 – 2.5), high Na 2 O values (&gt; 3 wt %) and staurolite mineral. Their pelitic and mafic attributes were derived essentially from a quartz-diorite, granodiorite and granite-quartz monzonite source. Fractional crystallization and partial melting of older dioritic-granodioritic-tonalitic source rock derived from upper mantle materials contaminated by continental crust played important roles during their genesis. They are enriched in Large Ion Lithophile Elements (LILE) but depleted in Nb, P and Ti typical of volcanic arc and syn-collisional settings. Keywords : Banded gneiss, Pan-African, sedimentary, igneous, granodiorite, protolith, Kushaka, Nigeria DOI: 10.7176/JEES/11-4-05 Publication date: April 30 th 2021