49 the Geology and Mineralogy of Clay Occurrences Around Kutigi
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Ethiopian Journal of Environmental Studies and Management Vol.3 No.3 2010 The Geology and Mineralogy of Clay Occurrences Around Kutigi Central Bida Basin, Nigeria. *Akhirevbulu O.E. Amadasun C.V.O., Ogunbajo M.I. and Ujuanbi O. Abstract This paper reports the geology and mineralogy of the clay occurrences around Kutigi. The methodology of research includes detailed mapping of the area, collection of clay samples and laboratory analysis using X- ray diffraction. Field results show that clays in Kutigi are deposited as alluvial deposit from braided and meandering streams and occur in two locations A and B. The deposits are of varying thicknesses and are capped by thin lateritic soil. The clay varies from white to dirty- white in colour as a result of the decolouration from the laterite overburden. The gritty feel of the clay from hand specimen is attributed to the clay-sand admixture, an indication of proximal overbank environment. The results from X-ray diffractogram show that the clay mineral is predominantly kaolinitic with a percentage abundance of about 43.64%. The high dominance of quartz with a percentage abundance of about 54.55% further confirms the grittiness of the clay. Illite constitutes about 1.18% and occurs in traces amongst other minerals. The above results and an earlier geochemical analysis suggest that it can be utilized in the manufacture of ceramics, refractory bricks, paper, paint and fertilizer. Introduction lay is a common name for a the country. For instance, clay deposits occur Cnumber of fine-grained, earthy in Abak, Akwa Ibom State, Uruove near materials that become plastic and tenacious Ughelli in Delta State, Ifon in Ondo State, when moist, and that becomes permanently Mokola in Oyo State, Sokoto in Sokoto State, hard when baked or fired. According to Gombe in Gombe State, Dangara in Niger (Velde, 1995), clay is applied both to materials State, Umuahia in Abia State, Onitsha in having a particle size of less than 2 Anambra State and Kutigi in Niger State. e.t.c. micrometers and to the family of minerals that The focus of this work is to investigate the has similar chemical compositions and occurrences of clay around Kutigi, as well as common crystal structural characteristics. to determine its mineralogical properties. Clay is formed either as a product of the The study Area. chemical weathering of pre-existing granitic The study area (Kutigi) is situated in rocks and feldspar minerals, particularly in Lavun Local Government Area of Niger State, warm tropical and subtropical regions of the within Bida basin. It lies between longitude 5 o world or as a result of the hydrothermal 35 1 E and 5 o 39 1 E and latitude 9 o 10 1 N and 9 o alteration of granitic rocks. 13 1 N and covers an area of about 39.88km 2 Chemically, clays are hydrous aluminum (Fig. 1). Kutigi is the major town in the area, silicates, ordinarily containing impurities, for while the surrounding villages include Kusogi, example potassium, sodium, calcium, Shebe, Makufu, Fazhi and Ruga. magnesium, or iron, in small amounts, and are The physical landform of Kutigi area characterized by sheet silicate structures of is made up of flat-lying to gently rolling plains. composite layers stacked along the c-axis The monotony of the landscape is however (Grim, 1968). Clay has a wide variety of broken by residual hills, which are either physical characteristic such as plasticity, conical or flat-topped. The area is mark by a shrinkage under firing and under air-drying, NW−SE and a NE−SE running ridges that are fineness of grain, colour after firing, hardness, prominently composed of laterite. The ridges cohesion, and capacity of the surface to take ranges from 15m to 50m in height as observed decoration. along the road cutting between Kutigi town Clay and clay minerals have been and Ruga village. The terrain is mostly mined since the Stone Age and has been covered by laterite and fairly by sandstone as a indispensable in architecture, in industry, and result of the weathering activities that have agriculture. Today they are among the most depleted the hills and ridges. The area is important minerals used by manufacturing and particularly drained by river Toro which run environmental studies. Globally, clay has a near Kusogi village and flow in the NE wide spread occurrence. In Nigeria, clay is direction of Egbako SW. Many insequent widely distributed though not always found in streams that enters river Toro as tributaries are sufficient quantity or suitable quality for seasonal and forms a dentritic drainage pattern modern industrial purposes. More than 80 clay which strongly suggest that the terrain is deposits have been reported from all parts of * Department of Physics, Ambrose Alli University, Edo State, Nigeria [email protected] 49 The Geology and Mineralogy........... Akhirevbulu, et al EJESM Vol.3 No.3 2010 composed of lithological, structural and of Technology, Minna to amount between topographic homogeneity. 1270mm – 1524mm, spread over the month of Though the rainy season and dry April – October with the highest amount season are the two known climatic seasons, it received in the month of July. Mean annual is worthy to note that the duration of any of temperatures are between 22 oC and 33 oC these seasons may vary locally from one area although there could also be local climatic to another- this is the case of Kutigi. Its annual changes. The vegetation is characterized by rainfall have been determined by the patches of woodlands and long grasses in river Department of Geography, Federal University valleys and fairly low hills. Kutigi (a) (b) Fig. 1: LOCATION MAP OF KUTIGI AREA WITHIN NIGERIA AND BIDA BASIN 50 Ethiopian Journal of Environmental Studies and Management Vol.3 No.3 2010 Review of Literature Adeleye (1971), and Adeleye and as residual clay due to the weathering of Dessauvagie (1972) identified clays in the feldspar from feldspathic sandstone. The clay Middle Niger Basin or the Nupe sandstone was noted to be suitable as raw material to the now renamed the Nupe Group. They studied ceramic, paper, refractory and paint industries the Stratigraphic succession in the area and respectively. reported the direct overlying of the basement General Geology of the study area complex by a coarse conglomerate, clay- The area of study falls within Bida sandstone admixture, boulders etc of Basin, which extends from Kontagora in Niger sedimentary origin. These, according to State to Dekina in Kogi State where it merges Adeleye, were themselves overlain by with the Anambra Basin. The total length of sandstone, and subsidiary claystones, Bida basin was estimated at 400km with a conglomerate and siltstones. maximum width of about 160km. The basin is The University of Ife (Adegoke, 1979) bounded to the North and South by the and Ahmadu Bello University Consultancy Precambrian basement rocks. The largest team also studied clays in parts of Bida basin. portion of the basin (the central part) occurs in Adegoke, (1979) worked on the structural the southern half of Niger State and constitutes properties of these clays at temperatures of the study area (Fig. 1.). The age of the 600 oC -1000 OC. All the clay occurrences sediment is Maestrichtain as determined by Jan investigated fall within the Cretaceous du Chene et al (1978) from pollens in Lokoja Maestrichtian in middle Niger basin (Bida formation to the south, which Adeleye (1973, Basin). The two main types of clays in the area 1975) considered to be laterally equivalent to are the earthy brownish to red lateritic clays the Bida sandstones. The origin of the basin is and the grayish ball clays. There are also the believed to result from the reactivation of whitish and silty kaolinites. The lateritic clay mega-shears in the Precambrian basement, occurs beneath thin to thick covers of laterite which created fault patterns trending northeast- on residual hills. The earthy lateritic clays are southwest and northwest-southeast (Kogbe, ubiquitous in occurrence. The grayish ball- 1981). A rift origin for the basin has been clays within the Bida basin occur on alluvial postulated by Kogbe (1981) whilst Whiteman plains of rivers. These are seemingly (1982) suggested the basin to have been secondarily derived clays deposited from formed from simple cratonic sag. The suspension load in the streams. They are sedimentation data presented suggest that the generally plastic in nature. There are other central Bida basin was formed by rifting or by similar clays but those are derived from the cratonic sagging. feldspar rich basement rocks (Adegoke, 1979). The first hill visited (which he called Research Methodology location A) is located behind ministry of works Detailed field mapping was carried out north east of Kutigi town. The second hill around Kutigi in order to establish the local visited (which he called location B) is located geology of the area. The method of behind Sharia Court, north west of Kutigi investigation involved an intensive fieldwork, town. He explored and estimated the reserve which lasted for eight days. For the purpose of extent of the clay deposits. Geophysical this study, a map extract was adopted from a evidence of Alabi, (2005) suggests that the topographical map on sheet 183 of Egbako SW total reserve of the Kutigi clay deposits are of Niger State at a scale of 1: 12,500. During estimated to about 672,579 tons, with an aerial the fieldwork, accessibility and collection of extent of about 57,400m 2 of clay bed in soil samples in the study area were made location A, and also an area extent of 300m 2 in possible by walking along roads and footpaths. location B. The results of his physical analysis On the field, the soil exposures were observed show medium plasticity index average of 30%, and described based on their colour, texture, Specific gravity of 2.61 and medium linear structural elements and mode of occurrences.