Suitability of Igbodogi Migmatitic Rock as an Industrial Raw Material

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1 International Journal of Engineering and Technology Volume 5 No. 3,March, 2015 Suitability of Igbodogi Migmatitic Rock as an Industrial Raw Material 1 BOLUWADE E. A and 2 AYODELE C. O Department of Minerals and Petroleum Resources Engineering Technology The Federal Polytechnic, Ado Ekiti, Nigeria. ABSTRACT Ten samples of migmatitic rock collected from the study area using a geologic hammer. The samples were prepared for laboratory test, one surface of each was grounded smoothly using 120,220 and 3F grade caborundum abrassive. A thin section of 30 microns thickness prepared from each sample mounted and studied under a petrological microscope. The results obtained revealed that plagioclase feldspar has the highest average percentage occurrence, while opaque mineral has the lowest average percentage occurrence. The percentages of quartz and feldspar observed to be significant. The rock could therefore be suitably used as industrial raw material for decoration. Large carbochon could be used in the manufacture of belt buckles, boloties, boloches, diverse decorators and functional pieces such as paper weight. Keywords; Carborundum, Opaque, Migmatitic, Petrological 1. INTRODUCTION Migmatite is a rock of both metamorphic and igneous origin that exhibits characteristics of both types. Carlos et al, (2008) defined migmatite as a composite rock body containing two types of rock ( igneous and metamorphic rock) that have interacted with each other nevertheless still distinguishable. Generally, migmatite is a heterogeneous silicate rock with properties of both igneous and metamorphic rocks believed to have been probably formed through the heating (but not melting) of rocks in the presence of abundant fluids. Typically the rock contain alternating lighter layer called leucosomes, which is made up of lighter colour minerals such as quartz, feldspar, muscovite and dark layer called melanosomes which is made up of dark-colour minerals such as amphibole and biotite (Anthony et al., 1996). It can be formed through migmatization. Olarewaju (2002) reported that migmatization is the process whereby a rock undergoes partial melting during extreme metamorphism, producing new rock called migmatites. The final product of migmatization may be mixed granite, hence from the whole process, it is almost granitization synonym. Rahman, (2004) reported that migmatite look very similar to a related rock called gneisses which also contains alternating light and dark layers which resulted under high pressure and temperature conditions. According to Ogezi, (2004) these two rock types are certainly relatives, in that when a gneiss experience slightly high temperatures, it may partially melt and become a migmatite. Most migmatites probably were gneisses as they turn to true hybrid metamorphic-igneous rocks. The presence of migmatites was one line of evidence examined to determine that granites could probably be formed through melting processes, not through chemical alteration process (Ajibade 1972). The word migmatite was first introduced into the geology literature in 1907 by Jacob Johannnes Sederholm and literally mean mixed rock originating from the ancient Greek. Findings have revealed that many migmatites are rich in silica (Brown et al 2009). It is essential to ascertain the suitability of the migmatite at Igbodogi, Ado Ekiti, through petrographic study for the abundance of Precambrian rocks in Ekiti State Nigeria and their great economic potential in their exploitation for building, construction and dimension stone. Ekiti State is blessed with lots of industrial rocks and minerals including Migmatite. This study is aimed at identifying and studying the mineralogical, structural and textural features of the Igbodogi migmatite rock samples. The implication of this on their utilization as an industrial raw material would be assessed. Migmatite often appear as tightly, incoherently folded (ptymatic folds) dikelets, veins and segregations of light colored amphibole and biotite rich material Called the melanosome (Oyawoye,2001).He also reported the light colored material has the appearance of having been mobilized or moltened. Once enough leucosomes, join up to form a network and granite is produced, the residual material is known as restite. Older granite consists of the minerals quartz, feldspar, and muscovite), on the other hand, crystallized from partial melts of the precursor rock. Migmatite textures are the product of thermal softening of the metamorphic rocks. Schlieven textures are common examples of granite formation in migmatites and are often seen in restite xenoliths and around the margins of s-type granites. The older granite rocks could occur as intrusions within the migmatite-gneiss-quartzite complex. The granitic rocks outcropped as domes and small hills in the area. The granites are distinguishably unique because of their visible minerals, lack of foliation, fine-medium grained texture and compacted interlocking crystals that developed during the crystallization of magma. However, granitic rocks of porphyritic texture occurs around Ado-Ekiti, Ikere-Ekiti and close to Ikole Ekiti. Some of the outcrops occur as well-rounded boulders devoid of any preferred orientation of component minerals. The ISSN: IJET Publications UK. All rights reserved. 134

2 contact relationship of the older granite with surrounding country rocks are abrupt in few cases while most are gradational over very short distances. Generally, the porpyritic granite is light coloured with signs of having been fairly weathered. Basement complex rocks are subdivided into migmatite-gneiss complexes ; the older metasediments, the younger metasediments, the older granites and the younger granite alkaline ring complexes and volcanic rocks. The migmatite gneiss complex is the commonest rock type in the Nigeria Basement complex (Rahaman,1976). It comprises two main types of gneisses. The biotite gneiss and the banded gneiss. The biotitic gneiss are normally finegrain with strong foliation caused by the parallel arrangement of alternating darkened light minerals.the banded gneisses show alternating light coloured and dark bands and exhibit intricate folding of their bands. Migmatite gneiss complex is the oldest basement rock believed to be of sedimentary origin but was later profoundly altered into metamorphic and granite conditions. The older metasediment were also among the earliest rock to form on the Nigeria basement complex. 2. MATERIALS AND METHODS the geological laboratory Department of Geology, Obafemi Awolowo University(OAU) Ile-Ife, where the samples were reduced to thin section of about 30micron thickness. The thin sections were analysed petrographically in the laboratory. Thin Section Preparation Chip sample of about 8-10mm diameter obtained from each of the samples using a geologic hammer. One surface of each sample was smoothened using120,220 and 3F grade caborundum abrasive. The surface was glued to the slide by lakeside70ºc cement in a hot plate at 80ºC to 100ºC.The other side of the rock is then reduced to thickness of 1mm with diamond saw. It was further reduced to 0.2mm with the aid of 100µm size caborundum. A 60µm size caborundum was later used to reduce the thickness to 0.1mm, a stage where quartz and feldspar show bright second order interference colours under crossed polar. The final grade of grinding is from 0.1mm to 0.03mm which is accomplished by using 12µm size caborundum. The rock was carefully reduced to 0.03mm while maintaining a uniform thickness over the whole area. At such standard thickness, a canada balsam diluted in xylene is used to mount the transparent rock onto the glass slide. The study area is located at 07º 36¹ 52.56¹¹ N and 05º 18¹ 03.24¹¹ off Ado-Ijan Road at a distance of about 3km (Fig.3). The outcrop is extensive and low-lying, accessible through graded road and foot path. Ten samples of migmatitic rock were collected in the study area with the aid of geologic hammer, properly labeled (L1-- --L10) and kept in a sample bag. The samples were taken to Fig 1 Map of Ekiti State Showing Ado Ekiti in Nigeria (Source Google) ISSN: IJET Publications UK. All rights reserved. 135

3 RESULTS TABLE 1: RESULTS OF ESTIMATED AVERAGE MODAL ANALYSIS OF MIGMATITIC ROCK SAMPLES FROM IGBODOGI SAMPLE NO QUARTZ PLAGIOCLASE FELDSPAR ALKALI- FELDSPAR (MICROCLINE) HORNBLENDE BIOTITE A L B L C L D L E L F L G L H L I L J L OPAQUE Average conc. Minerals LEGEND : Q = QUAR0TZ M=MICROCLINE B = BIOTITEGIOCLASE O= OPAQUE P = PLANEGIOCLASE H= HORNBLENDE XPL = CROSSPOLAR PPL= PLANEPOLAR CONC. = Concentration RESULTS OF PETROLOGICAL ANALYSIS PLATE 1a: PETROGRAPHY OF SAMPLE A MINERAL CONTENT: QUARTZ (28.2), PLAGIOCLASE (26.5), MICROCLINE (18.6), HORNBLENDE (9.4), BIOTITE (16), OPAQUE (1.3) TEXTURE: PORPHYRITIC. MAGNIFICATION: X80 ISSN: IJET Publications UK. All rights reserved. 136

4 PLATE 1b: PETROGRAPHY OF SAMPLE B MINERAL CONTENT: QUARTZ (30.1), PLAGIOCLASE (24.5), MICROCLINE (17.4), BIOTITE (17.2), HORNBLENDE (8.2), OPAQUE (2.6) TEXTURE: PORPHYRITIC. MAGNIFICATION:X80. PLATE 1c: PETROGRAPHY OF SAMPLE C MINERAL CONTENT: QUARTZ (31.4), PLAGIOCLASE (27.6), MICROCLINE (19.2), BIOTITE (10.2), HORNBLENDE (9.8), OPAQUE (1.8) PLATE 1d: PETROGRAPHY OF SAMPLE D MINERAL CONTENT: QUARTZ (31.4), PLAGIOCLASE (30.6), MICROCLINE (19.8), BIOTITE (12.2), HORNBLENDE (5.1), OPAQUE (0.9) ISSN: IJET Publications UK. All rights reserved. 137

5 PLATE 1e: PETROGRAPHY OF SAMPLE E MINERAL CONTENT: QUARTZ (24.6), PLAGIOCLASE (33.4), MICROCLINE (20.2), BIOTITE (13.5), HORNBLENDE (6.2), OPAQUE (2.1) TEXTURE: PORPHYRITIC. MAGNIFICATION ; X80 MINERAL CONTENT: PLAGIOCLASE (40.6), QUARTZ (22.4), MICROCLINE (21.4), BIOTITE (10.4), HORNBLENDE (4.6), OPAQUE (0.6) PLATE 1g: PETROGRAPHY OF SAMPLE G MINERAL CONTENT: QUARTZ (27.9), PLAGIOCLASE (30.7), MICROCLINE (18.9), HORNBLENDE (8.6), BIOTITE (12.4), OPAQUE (1.5) ISSN: IJET Publications UK. All rights reserved. 138

6 PLATE 1h: PETROGRAPHY OF SAMPLE H MINERAL CONTENT: QUARTZ (20.0), PLAGIOCLASE (41.1), MICROCLINE (20.0), HORNBLENDE (4.4), BIOTITE (12.4), OPAQUE (2.1) PLATE 1i: PETROGRAPHY OF SAMPLE I MINERAL CONTENT: QUARTZ (26.8), PLAGIOCLASE (36.4), MICROCLINE (12.3), HORNBLENDE (7.2), BIOTITE (15.4), OPAQUE (1.9) PLATE 1j: PETROGRAPHY OF SAMPLE J MINERAL CONTENT: QUARTZ (40.0), PLAGIOCLASE (43.6), MICROCLINE (8.2), HORNBLENDE (2.4), BIOTITE (5.0), OPAQUE (0.8) ISSN: IJET Publications UK. All rights reserved. 139

7 DISCUSSION From the average modal analysis of the Igbodogi migmatitic rock sample (Table1), plagioclase feldspar has the highest average occurrence while opaque has the lowest percentage occurrence. This could have been suggestive of the more of leucosome than the melanosome portion in the migmatites at Igbodogi. Berry,(2001),plagioclases are common in granites and granitic pegmatites. It is an evidence in support of magmatic origin for the migmatite. The leucosome is generally rich in quartz and feldspars(carlos et al,2008).the presence of plagioclase feldspar indicate that the migmatitic magma have been produced at spreading centres representing materials which is different from the upper mantle. The presence of opaque minerals at such average percentage concentration of 1.5 could be an indication that metallic minerals are present in the migmatitic complex at igbodogi. Iron oxide could be suspected since the rigorous laterisation at the tropics is a possibility. The slide (Plate 1a-j) is porphyritic in texture, crystals of plagioclase and alkali feldspar are commonly embedded in finer groundmass of biotite and quartz. The cooling history of biotite and quartz magma faster than that of feldspar, the biotite and some quartz could have constituted the neosome. Plate j, the alignment of biotite is observed and could be due to the extensive deformational history of migmatite. Sawyer, (1998) such alignment could be related to ptygmatic fold that is formed by highly plastic ductile deformation of the gneissic banding, this have little or no relationship to a defined foliation unlike most regular fold. CONCLUSION Igbodogi migmatitic rock is majorly porphyritic in texture, more of leukosome (older) portion than neosome (new) portion. The percentage of quartz and feldspar are significant; such discoveries will make the rock to be recommendable as industrial raw material for decorating granite or Rainbow Gneiss. Large carbochon could be used for belt buckles, bolo ties and boloches, diverse decorators and functional pieces paper weight and book end. REFERENCES Anthony, H (1996):Igneous petrology, Longman Group Ltd, England, 4 th Edition,Pg Berry, L.G (2001):Concepts, Descriptions, Determinations 4596/1-A, New Delhi, India. CBS Publishers and Distributors Second Edition pg 406. Brown, M and Stephen, M.(2009). Essentials of Geology, W. W. Norton 3 rd Ed,pp. Carlos, A. Zuluaga, C and Harold H S.(2008):Multidisciplinary Approach to Study Migmatites: Origin and Tectonic History of the Nason. Ridge Migmatitic Gneiss, Wenatchee Block, Cascades. Crystalline core, WA. USA.Earth Science Research Journal, vol 12 nos 2 pg 1-2 Cooray,S and Rahaman M. A (2004):Review of Basement Complex of South-western Nig. Ibadan, Eds. Ibadan University Press Pg Ekwueme B.N(2001):Geochemistry and Economic value of Igneous Rock in the Precambrian Basement South East Nigeria. IBM publishing, New Delhi, pg Harris, N.B.W and Inger,S (1992).Trace element modeling of pelite-derived granites. Contributions to Mineralogy and Petrology 110,pg Ogezi, I.G.(2004):Precambrian Geology of Nigeria, Geological Survey of Nigeria,Kaduna,pg Olarewaju V.O (2002).The Chemical and Physical Characteristics of Charnokite from Ado and Ikere Ekiti In Precambrian Geology of Nigeria, Copyright GHS Pg Oyawoye M.A (2001):Geology of Basement Complex. Journal of Nigeria Mining, Geology and Metallurgy vol 1pg Patino Douce, A.E and Beard J.S (1996).Effects of P,(O 2) and Mg/Fe ratio on dehydration-melting of model metagreywackes. Journal of Petrology pg 37, Sawyer,E. W.(1998). Atlas of Migmatites. The Canadian mineralogist special publication( 9). Mineralogical Association of Canada, Research press, Ottawa. Wright J B (2002): Volcanic Rock in Nigeria in Geology of Nigeria12 th Reversed Edition, Kogbe C A (Ed.) Rock view (Nig.) Ltd, Jos Nigeria, pg ISSN: IJET Publications UK. All rights reserved. 140