STRATIGRAPHY AND SEDIMENTOLOGICAL STUDIES OF THE ALBIAN TO MAASTRICHTIAN SEDIMENTS AROUND LAFIA TOWN, LAFIA SHEET 231NW MIDDLE BENUE TROUGH, NIGERIA
STRATIGRAPHY AND SEDIMENTOLOGICAL STUDIES OF THE ALBIAN TO MAASTRICHTIAN SEDIMENTS AROUND LAFIA TOWN, LAFIA SHEET 231NW MIDDLE BENUE TROUGH, NIGERIA
No Thumbnail Available
Date
2021
Authors
HARUNA, JAPHETH NUFI
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
The middle Benue Trough is one of the three segments of the larger NE-SW trending Benue Trough. As is the case with the Upper Benue Trough, there does not seem to be any recent work dedicated to the Geology of the Middle Benue Trough. Recent works on the stratigraphy and sedimentological studies of the Albian to Turonian sediments of the middle Benue Trough, covered areas around Keana and Awe respectively (all within sheet 232 NW). This work covered Areas within Lafia (Sheet 231NW). The study area is located southeast of Lafia town. It is accessible by some major roads which includes: Lafia to Makurdi, Doma to Agyaragu and Lafia to Keana. Reconnaissance study was first carried out in the study area on a scale of 1:100000 followed by a detailed field mapping on a scale of 1:50,000. In the course of the field work, the lithostratigraphic successions in the study area was established, sedimentary structures were identified and samples collected for petrographic and sieve analysis. Stratigraphic study in the study area indicates the occurrence of three formations namely; the fluvial Lafia Formation (Campano-Maastrichtian), the shallow marine Awgu Formation (Turonian-Coniacian) and the transitional Awe Formation (Albian-Cenomanian). A total of 12 samples were collected for granulometric analysis, and 11 samples for Petrographic analysis. The Lafia Formation consist of ferrugenised sandstone at the base, clay and clayed loosed sands. Petrographic and sieve analysis revealed that the Ferrugenised sandstone range from fine-medium grain. It is moderately sorted, strongly fine skewed and is a Quartz arenite. More than 60% of the crystals are monocrystalline which is indicative of igneous provenance. The Awe Formation consists of fine-grained white sandstone, with some intercalations of white clay and laminated shale. The sandstones are fine-grained and poorly-moderately sorted which coupled with the bivariate plot that indicates a transitional conditions between shallow marine and fuvial systems. The sandstones of the Awe Formation range from Arkose to Subarkose. The presence of monocrystalline quartz and plagioclase feldspars are all indicators of igneous provenance. The Awgu Formation consists of sandstones that are fine grained, very poorly sorted and strongly fine-skewed. The sandstones of the Awgu Formation are Quartz Arenites. There are ostracodes, echinoderms, and ammonites fossils within the shaley limestone and limestones of the Awgu Formation. This is an indication of a shallow marine environment of deposition. The Sedimentary structures in the study area include; beddings, mudcracks, faults, joints and veins and unconformity. The bedding planes are indications of break in deposition of the sediments while the mudcracks indicates long exposure to a dry warm climate. Other Methods of studies such as aeromagnetic studies, palynological studies and diagenetic studies should be carried out for more geological information of the study area to properly characterise the Middle Benue Trough
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES AHMADU BELLO UNIVERSITY, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF A DEGREE OF MASTER OF SCIENCE IN GEOLOGY
DEPARTMENT OF GEOLOGY,
FACULTY OF PHYSICAL SCIENCES,
AHMADU BELLO UNIVERSITY,
ZARIA, NIGERIA