Query: Precambrian rocks of Nigeria

title: Geology and petrography of precambrian rocks of Katsina urban area, northwestern Nigeria
abstract: Researches Review DGTH 49 2, 113 126 2020  This present study, the mapped area is located between latitude E07deg35'00' to E07deg39'0011" and longitude N13deg00'00' to N12deg57'00" of sheet 34NW, Katsina State, Northern Nigeria. The area is underlain by Basement Complex rocks and syenogranitic rocks which dominate in the area. The two sets of granitic rocks were observed and distinguished by texture. The northwest of the mapped area consists of very coarse to coarse grained syeno granitic rocks, while in the southeast, the rocks are medium to coarse grained. These outcrops exhibit various systems of joints. The mineralogical compositions determine by thin section results displays: quartz, biotite, muscovite, plagioclase feldspar, apatite, sericite, hornblende, augite and microcline. There are two generalizations of joints with primary WSW to ENW direction and NE SW, MMW SSE and WWW ESE secondary direction of NE SW, MME SSE and WWW ESE.

title: Geology, Geochemistry and Petrogenesis of Precambrian Rocks of Part of Sheet 244 of Ado Ekiti, Southwestern Nigeria
abstract: The geology, geochemistry and petrogenesis of Precambrian rocks of part of sheet 244 (Ado Ekiti) Southwestern Nigeria is reported in this paper. The study area was mapped systematically and the lithologies encountered include migmatite gneiss, granite gneiss, older granite, and charnockite. The various structures mapped on the outcrops are compositional banding, pinch and swell structures, joints, xenolith inclusions among others. The gneisses cover the largest proportion (60% of the study area while the Older granites and charnockites cover the North Eastern and Southwestern part of the area. Six fresh samples of rocks were analysed for petrographic study while another six representative samples (2 per rock type) were also analysed for geochemical composition using Atomic Absorption Spectroscopy. The petrographic study reveals the dominance of quartz, biotite, plagioclase and microcline in the thin sections for the different rock types. The geochemical analyses of the rocks show in percentage average SiO 2 compositionof 67.63 in charnockites, 67.09 in granites and 67.99 in gneisses. Alumina varied from 13.77% in the charnockites, and the lowest in the gneisses with 12.91%.The high percentage composition of SiO 2 obviously indicate siliceous nature of all the rock units in the area with low content of Fe 2 O 3 and MgO as well as various discriminatory diagrams establishing a common petrogenetic origin related to igneous material source.  Lithologies, Precambrian, Geochemistry, Petrogenesis, Protolith

title: Geochemical characterization of Granitoids in Katchuan Irruan area: further evidence for peraluminous and shoshonitic compositions and post collisional setting of granitic rocks in the Precambrian Basement Complex of Nigeria
abstract: Petrographic studies on Granitoids from Katchuan Irruan and adjoining areas, southeastern Nigeria, has shown that they are garnetiferous biotite granite, aplitic granite, porphyritic hornblende biotite granite, porphyritic muscovite biotite granite, weakly foliated leucogranodiorite and simple pegmatite. They are closely associated with the Precambrian Basement Complex rocks which they intruded. Modal analysis shows that the rocks consist of quartz (10% 25% oligoclase (10% 30% K feldspar (15% 35% biotite (3% 25% with occasional garnet, hornblende, muscovite, and accessory chlorite, haematite and magnetite. Geochemical data indicates that the rocks are generally shoshonitic, alkali calcic to calcic, ferroan and peraluminous. They are enriched in large ion lithophile elements as well as high field strength elements (Hf, Ta, Yb, Sm, Zr and Y) Their trace elements and REE patterns are similar, indicating that they are co genetic. They are characterized by high fractionation factor (La/Yb)N (3.04 228.44) and pronounced negative Eu anomalies (Eu/Eu* (0.23 0.71) Their overall geochemical features indicate that they were most likely derived from partial melting of crustal materials in an orogenic (post collisional) tectonic setting. They are therefore related to the Pan African granites, otherwise known as the Older Granites which were emplaced during the Pan African orogenic event.

title: Base Metal Mineralization in the Precambrian Rocks of Okemesi Ijero Area, Southwestern Nigeria
abstract: The evaluation of base metals in the bedrocks of Okemesi Ijero area, southwestern Nigeria has been carried out to assess their potentials, level of accumulation and enrichment. The methodology included systematic geological and geochemical mapping of the rocks using grid controlled sampling method at a sampling density of one sample per 500m. Ten rock samples were collected at different locations of the study area. The results obtained showed that the major oxides such asA SiO2, Al2O3, TiO2, Fe2O3, MnO, MgO, CaO, Na2O, K2O and P2O5 were detected in variable proportions. While SiO2 variedbetween 70.59% and 98.70% Al2O3 ranged between 15.73% and 0.61% There is abundanceof barium (Ba) silver (Ag) andA gold (Au) with concentration values of 1.6 9.8, 1.24 7.1 and 0.05 10.00 ppm respectively. Base metals such as Cu, Zn, Pb, Bi and Cr enrichment factors and their geo accumulation index indicates moderately significance to very high enrichment of Cu (10 aEUR" 70% Pb (20 aEUR" 40% and Bi (10 aEUR" 40% The geo accumulation indices suggest geogenic concentration of the base metals in the host rocks rather than anthropogenic inputs. The PCA elements loaded Au, As, Ag, Pt and Os on the same factor and they are pathfinder elements of Gold. Correlation coefficients indicate strong positive correlations between the elements. This implies that they are strongly related and therefore of the same source, also suggesting geogenic sources.

title: Geochemical characteristics of Precambrian Basement rocks from southeastern Nigeria: an approach to their petrogenesis and tectonic setting.
abstract: Trace and Rare Earth element geochemical study of twenty samples of migmatitic banded gneisses, garnet biotite schists, dolerites, granites and rhyolites was carried out in a bid to determine their petrogenetic and tectonic significance in the evolution of the southeastern Basement complex of Nigeria. The data shows that partial melting (crustal anatexis) of migmatitic gneisses and schists played a significant role in the evolution of the granitic intrusions. This is supported by the high incompatible (Rb/Sr 0.16 to 1.31 and Ba/Sr 0.75 to 6.21) elements ratio in the granitic intrusions than that of the migmatitic gneisses and schists (Rb/Sr, 0.051 to 0.824; Ba/Sr, 0.7 to 5) High ratios of Ba/Sr and Rb/Sr and lesser values of Ba/Rb ratios in some granitic intrusions than in others suggests increasing fractionation during the anatexis. The role of partial melting is also evident in the smooth REE patterns shown by most of these rocks and the negative Eu anomaly as indicated by the values of Eu/Eu* (0.097 to 0.7) LREE enrichment is evident in the high values of Ce/Yb N (12.08 174.5) La/Yb N (15.2 228.4) and La/Sm N (2.6 7.2) in the granitic intrusions. Tectonic discrimination diagrams of the rocks indicate that the basement rocks were most probably formed in a post collision orogenic setting while the dolerite and the rhyolite were formed in within plate anorogenic setting.

title: Statistical variability of radiation exposures from Precambrian basement rocks, NW Nigeria: Implication on radiogenic heat production
abstract: The heat flux system within the Precambrian basement complex in northwestern Nigeria has been poorly studied and little is known about the potential of the constituent petrologic units as regards geothermal resources. The earth crust gets heated up by a combination of processes, prominent among them is radioactive decay of 40K, 232Th and 238U radionuclides. Radioelement concentrations were measured within the rock units that dominate the basement complex namely quaternary sediments, carbonates, metasediments, younger granites, metavolcanics, older granites, migmatite and gneissic rock. Statistical parameters were estimated to deduce the radioactive absorbed dose of the various rock units. Quaternary sediments recorded the lowest mean dose while gneissic rock recorded the highest mean dose given as 112.09 nGy.h 1 and 264.54 nGy.h 1 respectively. One way analysis of variance performed in this study showed distinct statistical significant variations of the radioelement concentrations in the dose assessment of the rock units. The contributing percentages of the radioelements for all the studied rock units were in the order 40K 232Th 238U. Two major classes of rock unit namely clastic rocks and plutonic rocks were assessed for their heat production capacity. The clastic rocks comprising quaternary sediments and carbonates presented mean heat production units given as 0.528 uWm 3 and 0784 uWm 3 respectively while the plutonic rocks comprising granite and gneissic rock presented mean heat production units given as 1.404 uWm 3 and 1.982 uWm 3 respectively. Subsequently, heat generation unit estimations were extrapolated from the heat production values with gneissic rock showing the highest value given as 5.5660 HGU. These results which may assume theoretical pilot status towards geothermal resource investigation in northwestern Nigeria are in tandem with other similar studies performed around the globe.

title: Reconnaissance geological and geochemical studies of the Precambrian rocks in Erijiyan Area, Southwestern Nigeria: Implications for mineral exploration
abstract: Reconnaissance geological and geochemical studies were carried out on the rocks at Erijiyan area to determine its mineral potentials thereby providing a framework for its exploration. Ten fresh rock samples were collected using grid controlled sampling method at a sampling density of one sample per 100sq km2. The rocks were subsequently prepared for petrographic studies followed by geochemical studies. The petrographic studies involve thin sectioning of the rocks into slides using the standard procedures while the geochemical studies include sample preparation and analyses for its major oxides and trace elements using Inductively Coupled Plasma Spectrophotometry (ICP MS) The result of the geological mapping revealed three distinct lithologic units such as quartz schists, quartzites and pegmatites with well delineated boundaries, and the major or dominant foliation trend in the NE SW direction. However, the results of the petrographic analysis showed dominant quartz with minor specks of muscovite while results of geochemical analysis revealed the dominance of Al2O3 and SiO2 with the quartz having an average percentage composition of 64.73% Al2O3 indicated presence of aluminosilicate bearing minerals such as feldspar, micas, and feldspathoids. The results of the trace elements analyses revealed that Mn is the most abundant with an average value of 1065.2 ppm while the average concentrations of other trace elements showed that Ba (1166.9 ppm) Zr (819.4 ppm) Sr (227.9 ppm) and Zn (130.7 ppm) Conclusively, The weathering index shows that the rocks in the study area are moderately weathered implying that the rocks are suitable for geochemical or mineralogical exploration.Considering the geochemical properties of the rocks in the study area, It could be deduced that Pb, Cu, Zn concentration is indicative of copper zinc or sulphide mineralization. while. Pb, Sr, Ba and Zr also indicated the radio active nature of the rocks.

title: Petrochemistry and petrogenesis of the Precambrian Basement Complex rocks around Akungba Akoko, southwestern Nigeria
abstract: Field, mineralogical and petrochemical studies of the Precambrian Basement Complex rocks around Akungba Akoko were carried out with the aim of determining their petrology, petrochemical characteristics and petrogenesis. The petrology of Akungba Akoko area comprises migmatite, granite gneiss and biotite gneiss intruded by biotite granite, charnockite and minor felsic and basic rocks. Seventeen representative samples of the granite gneiss, biotite gneiss, biotite granite and charnockite were collected during field geological mapping of the area for petrographic and geochemical analyses. Modal mineralogy revealed that the granite gneiss, biotite gneiss and granite have assemblages of quartz feldspar mica hornblende opaques and are granitic in composition. The charnockite is characterized by anhydrous mineral assemblage of quartz feldspar biotite hornblende pyroxene opaques. Petrochemical data of the rocks revealed that they are moderately to highly enrich in SiO2, sub alkaline, peraluminous, magnesian to ferroan and calcic and have K/Rb 283. The geochemical characteristics and discrimination of the rocks indicated that the granite gneiss and biotite gneiss are orthogneisses formed by metamorphism of igneous protoliths of granitic composition and the biotite granite and charnockite are of igneous/magmatic origin. The biotite granite, charnockite and the igneous protoliths of the biotite gneiss are I type granitoids formed from crustal igneous sourced melt(s) while the igneous protoliths of the granite gneiss is a S type granitoid probably derived from shallow crustal or sedimentary sourced melt(s) Tectonic discrimination of the rocks indicated that they were formed during a phase of magmatic activity related to collision and subduction.

title: Geology and Petro chemistry of the Precambrian Rocks around Ipoti and Oke Ila Area, Southwest Nigeria: A Preliminary Investigation for Mineral Exploration
abstract: Pollution and shortages in clean water supplies are some of the most serious problems that humanity is facing. In many Asian countries and elsewhere, the demand for potable water doubles every 10 15 years due to rising domestic consumption and the increasing needs of industry  Eutrophication of municipal and industrial water reservoirs is a global concern and has been identified as a major environmental problem for water resource management. Furthermore, about 80 million tons of nitrogen fertilizers are applied globally per year to maximize yield  and no more than 40% of this amount is taken up by crops [4]

title: Integrated geophysical investigation of groundwater potential and bedrock structure in Precambrian basement rocks of Ife, southwest Nigeria