Journal of Environment and Earth Science www.iiste.org ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol.5, No.20, 2015 89 Sedimentological and Geochemical Appraisal of Stream Sediments of Part of Igangan Sheet 240 South Western Nigeria Owonipa Omoniyi Dare 1 Edema Abayomi 2* 1. Earth Sciences Department, Kogi State University, Anyigba. Nigeria 2. Geological Sciences Department, Achievers University, Owo, Nigeria Abstract An integrated sedimentological and geochemical evaluation was carried out on the sediments sampled from part of Igangan sheet 240 (1:100,000) SW Nigeria, covering Lanlate and its environs. This study is to characterize the provenance and depositional processes prevalent in the area. Twenty-nine stream sediment samples were collected after the confluence points of two or more rivers at a depth of 20-25cm, along with rock samples for further analyses in the laboratory. The techniques involved using standard sedimentological methods involving field descriptions, textural parameters, and petrographic analysis methods. The geochemical studies involved the determination of major elemental composition using Heavy Mineral analyses. Granulometric analysis was carried out on twenty-nine (29) stream sediments samples, while five (5) representative samples were systematically picked and analyzed for their mineralogical maturity using ZTR index. The rock samples were cut into thin section and analysed under the microscope for mineral composition. The results of the geochemical analysis were thereafter subjected to multivariate statistical analysis. The statistical plot shows that the sands are poorly sorted, medium to coarse grained and sub rounded to sub angular in shape. The sands which are medium to coarse grained suggests that the sands were deposited under a moderately energy condition. The field investigations and petrographic studies show that most of the study area has undergone an episode of metamorphism. Migmatite gneiss (80%), Biotite Hornblede Gneiss, quartzite (5%), muscovite hornblende biotite granite (10%) and biotite hornblende granite (5%) are the major rock in the area, while biotite, feldspar, quartz, hornblende and accessory minerals were observed in hand and thin sections. The calculated ZTR index for the sandstones ranges from 51.3% to 57.9 %, with an average of 54.6 %. This suggests that the sandstones of the formation are mineralogical mature. The conclusion drawn from the integration of the geochemical and multivariate analyses revealed that the study area is mineralized and the sediments were deposited under a moderate energy condition. Keywords: Igangan, Nigeria, Sedimentological, Stream sediments, Geochemical, Statistics 1. Introduction The textural parameters of surficial sands/sediments hold a lot of history regarding the provenance and environment of deposition of sediments in an area. This study was based on the geology and geochemical study of the sands and stream sediment samples collected from part of Igangan sheet 240 South-Western Nigeria; within the Nigeria basement Complex. The area of study covers major villages like Lanlate, Maya, Lagaye, Ogodu, Duduyemi, Alaye, and environ. The area is geographically between Latitudes 3 0 18 I to 3 0 30 I and longitudes 7 0 36 I to 7 0 42 I . It is an area covering about 288km 2 , a distance of about 12km by 24km. It is surrounded by basement rocks. The basement geology is characterized by distinct lithologies and mineralization. The sediment load of the river is predominantly those derived from the weathering of the surrounding basement rocks. Geological Investigation in this part of Nigeria started in 1905, when the then mineral survey of Western Nigeria conducted reconnaissance survey in the region. Since then several other workers have contributed their own quota to the advancement of knowledge on these area. One of the earliest studies of the Nigerian basement complex was made by Fulconer (1911), when he distinguished the older granite from the younger granite. Oyawoye (1964) carried out a reconnaissance survey of the basement complex and gave a descriptive account of its geology. Jones and Hockey (1964) studied the south western basement complex. Rahman (1976) gives an explicit description of the petrology and geology of the basement complex. Burke et al (1972) worked on the structure and sequence of geological events in basement complex of Ibadan area. Emofurieta W.O. (1985) also worked on the geochemistry and petrography of two prominent Gneiss in the basement complex around South west Nigeria. Despite the research into the geology of the region, no reported work has addressed detailed studies on the sedimentology and paleoenvironment. In order to present detailed insight in understanding the