This study is aimed at determining the geology and depositional environment of Ameki Formation in Bende and environs through field descriptions, textural analysis and Palynological analysis. The mapped area which covers an area of about 180sq km and is located around Bende, southeastern Nigeria. The study area is bounded by Longitude 07° 30` E and 07° 43` E and Latitudes 05° 30` N and 05° 39` N. The area is underlain by Paleocene Imo Formation and Eocene Ameki Formation. The Ameki Formation is a clastic unit that overlies the marine Imo Formation and it consists of sandstone, shales, limestone, ironstone and siltstones. The Eocene Ameki Formation in southeastern Nigeria consists, in its type locality of five lithologic units; calcareous sandstone, pebbly bioturbated sandstone, grey-dark shale, argillaceous sandstone and pebbly sandstone. The floral, faunal and lithologic studies of the Eocene Ameki Formation suggest sediments deposited in a continuity from nearshore (barrier-ridge estuarine complex) to shallow marine (intertidal and subtidal zones) environment. The sieve analysis unveils that the univariate parameters indicate a fluvially intercepted shallow marine environment with tidal crosscuts, the log probability plots suggest tidal environment while from the bivariate plots; a beach influenced fluvial environment is interpreted. The pebble morphological analysis showed that the pebble clast have being shaped by beach action as revealed by the bivariate scatter plots of pebble form indices while in multivariate aspect a fluvially dissected shallow marine environment with tidal interferences was interpreted. The palynological analysis indicated a marginal marine source for the sediment and that the formation (Ameki) is Eocene in age.
Table of Contents
1. Introduction
1.1 Background of study
1.2 Aim of study
1.3 Objectives
1.4 Scope of study
1.6 Limitations
2. Geomorphological Setting
2.1 Topography and drainage
2.2 Climate
2.3 Vegetation
2.4 Location and accessibility
2.5 People and culture
3. Literature Review
3.1. Regional tectonic setting
3.2. Regional Stratigraphic Settings
3.3. Lithostratigraphic setting of the Anambra Basin
3.3.1. Imo Formation
3.3.2 Ameki Group
3.3.2.1 Nanka Formation
3.3.2.2 Nsugbe Sandstone
3.4. THE GEOLOGICAL SETTING
3.5 Review of Previous Works
4. Method of Study
4.1. Preliminary Studies
4.1.1. Desk Study:
4.1.2. Reconnaissance survey
4.2. Field Study
4.2.1. Detailed Study
4.3. Facies Analysis
4.3.1 Lithofacies analysis
4.4. Laboratory Analysis
4.4.1. Textural Analysis
4.4.1.1. Sieve Analysis
4.4.1.1.1Methodology
4.4.1.1.2. Textural Parameters
4.4.1.1.3Indications from Bivariate Plots
4.4.1.1.4 Multivariate Analysis
4.4.1.1.5 Importance of the Sieve Analysis
4.4.1.2Pebble Morphology
4.4.1.2.1 Methodology
4.4.2 Limestone Thin Section Preparation
4.4.2.1 Methodology
4.4.2.2 Sample preparation
4.4.2.3 Petrographic and mineralogical analysis of limestone
4.4.2.4 Identification of limestone diagenetic records
4.4.3. Palynology Analysis
4.4.3.1. Equipment and Supplies for the Palynological Analysis
4.4.3.2 Essential Palynological Processing Procedures
4.4.3.3 Method of Sample Preparation
5. Results and Interpretation
5.1ENVIRONMENTAL INTERPRETATION
5.1.1 Indication from Facies Analysis
5.1.1.1 Outcrop Description
5.1.1.3 Lithofacies Association
5.1.5.4 Map interpretation
5.1.1.5 Sedimentary structures
5.1.2 INDICATION FROM SIEVE ANALYSIS
5.1.2.1Presentation of Results from Sieve Analysis
5.1.2.2 INTERPRETATION OF SEIVE RSULTS
5.1.2.2.1 Indication from bivariate plots
5.1.2.2.2 Indication from multivariate
5.1.3Indication from Pebble Analysis
5.1.3.1 Data Presentation
5.1.3.2 Interpretation
5.1.3.2.1 Indication Form Univariate Pebble Parameters
5.1.3.2.2 Indication from Bivariate Plots
5.1.4 Indication from Palynological Analysis
5.1.4.1 Results
5.1.4.2 Brief Summary of Age Determination
5.1.5 Indication from Thin Section Petrography
5.1.5.1 Results
5.1.5.2 Interpretation and Diagenetic features
6. Economic and Engineering Geology
6.1. Economic Geology
6.1.1. Laterites
6.1.2. Sandstones
6.1.3 Limestone
6.1.4 Ironstone
6.1.5 Clay and Shale
6.2 Engineering Geology
6.2.1 Geotechnical properties
6.2.2 Control measures for deformation of road in the study area
7. Environmental and Hydro Geology
7.1 Environmental Geology
7.1.1 Environmental implication
7.1.1.1 Erosion
7.1.1.1.1 Control measures
7.1.1.2 Quarrying activities
7.1.1.2.1 Control measures
7.1.1.3 Bad farming practices
7.1.1.3.1 Control measures
7.2. Hydrogeology
8. Summary and Conclusion
Research Objectives & Topics
This thesis aims to conduct a comprehensive geological assessment of the Ameki Formation within the Bende area, southeastern Nigeria. By utilizing field logging, textural analysis, and palynological examination, the study seeks to determine the depositional environment, stratigraphy, and potential economic utility of the local rock units, ultimately contributing to a better understanding of the area's geological and environmental framework.
- Geological mapping and field documentation of outcrops.
- Sedimentological analysis through grain size (sieve) distribution.
- Petrographic examination of limestones via thin section analysis.
- Palynological study for age determination and paleoenvironmental reconstruction.
- Assessment of economic and geotechnical properties of geological deposits.
Excerpt from the Book
4.2. Field Study
During the field work, outcrop are sited, observed and the position is marked using Global positioning system (GPS). This is followed by detailed logging of the outcrop taking note the rock type (lateral extent, gross thickness, bed thickness) textural features (color, grain size, and sorting of grains, clay content, cementation/ compaction if present), sedimentary structures (nature of bedding, internal structure), tectonic structure (fracturing, joints, faults, folds), and biogenic structures. This constitutes the central part of this work.
Chapter Summaries
1. Introduction: Presents the background of the field study, its aims, objectives, and the scope of research conducted in the Bende area.
2. Geomorphological Setting: Describes the physical environment of the study area, including its topography, drainage, climate, vegetation, and cultural context.
3. Literature Review: Provides an overview of the regional tectonic and stratigraphic frameworks, including the geological history of the Anambra Basin and the Ameki Group.
4. Method of Study: Details the field and laboratory techniques employed, including geological mapping, sieve analysis, thin section preparation, and palynological procedures.
5. Results and Interpretation: Interprets the collected data from outcrop logging, sieve analysis, pebble morphology, palynology, and petrography to reconstruct the depositional environment.
6. Economic and Engineering Geology: Evaluates the mineral potential of the area and discusses geotechnical challenges related to road construction and soil stability.
7. Environmental and Hydro Geology: Examines environmental hazards like erosion and bad farming practices, while also discussing the local hydrogeological characteristics.
8. Summary and Conclusion: Synthesizes the research findings, confirming the Eocene age of the Ameki Formation and its depositional history within a regressive sedimentary phase.
Keywords
Ameki Formation, Bende, Anambra Basin, Sedimentary Geology, Depositional Environment, Sieve Analysis, Palynology, Petrography, Limestone, Sandstone, Stratigraphy, Pebble Morphology, Eocene, Geotechnical Engineering, Nigeria.
Frequently Asked Questions
What is the primary focus of this research?
The work focuses on determining the geology and depositional environment of the Eocene Ameki Formation in the Bende area of southeastern Nigeria through systematic field and laboratory analysis.
What are the main thematic areas covered?
The study covers regional stratigraphy, sedimentology (texture and pebble morphology), palynology, thin section petrography, and the economic and engineering implications of the local geology.
What is the primary research goal?
The primary goal is to perform a detailed geological study and produce a geologic map of the Bende area while identifying the processes involved in the transportation and deposition of the local sedimentary units.
Which scientific methods are utilized?
The study employs a multi-disciplinary approach, including systematic field logging, sieve analysis for textural determination, thin-section petrography for carbonate analysis, and palynological techniques for age and environment determination.
What topics are discussed in the main body of the work?
The main body examines the geomorphological setting, literature on the regional tectonics, detailed methodologies for sample preparation, and the interpretation of results from various sedimentological and biological analyses.
Which keywords characterize this thesis?
Key terms include Ameki Formation, Bende, Anambra Basin, sedimentology, paleoenvironment, stratigraphy, palynology, and economic geology.
How was the depositional environment determined?
The depositional environment was inferred by integrating textural parameters (sieve analysis), morphological study of pebble clasts, and palynomorph assemblages, which collectively suggest a transition from nearshore to shallow marine environments.
What is the significance of the Ameki Formation's limestone?
The study evaluates the composition and economic value of the limestone, finding that while it meets various requirements, its limited minable volume restricts its broader economic significance.
How does the work address the issue of road deformation in the area?
The research analyzes the geotechnical properties of local mudrocks and suggests preventive measures, such as avoiding construction on certain units and utilizing laterites for road maintenance.
- Quote paper
- Chidera Ikechukwu (Author), 2017, Geology and depositional environment of the Ameki Formation in parts of Bende and environ Southeastern Nigeria, Munich, GRIN Verlag, https://www.grin.com/document/434661
