Keys to paleoenvironmental interpretation of the nkporo formation, afikpo sub...
GRANULOMETRIC ANALYSIS AND HEAVY MINERAL STUDIES OF BIMA SANDSTONE
1. 1
A PAPER REVIEWED BY
AGBAJE TITUS MAYOWA
Email Address: feelmayor@gmail.com
AT THE UNIVERSITY OF ILORIN, KWARA STATE, NIGERIA
GRANULOMETRIC ANALYSIS AND
HEAVY MINERAL STUDIES OF BIMA
SANDSTONE, UPPER BENUE
TROUGH: IMPLICATION FOR
PALEOENVIRONMENTAL
RECONSTRUCTION
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TABLE OF CONTENT
INTRODUCTION……………………………………………………………………………………………… 3
LITERATURE REVIEW ……………………………………………………………………………………… 4
LOCATION OF STUDY AREA…………………………………………………………………………….. 6
GEOLOGY OF THE STUDY AREA……………………………………………………………………….. 7
STATEMENT OF PROBLEM ……………………………………………………………………………… 11
JUSTIFICATION ……………………………………………………………………………………………….. 12
AIM & OBJECTIVES …………………………………………………………………………………………. 13
METHODOLOGY…………………………………………………………………………………………….. 14
EXPECTED RESULT AND VALUE ADDITION………………………………………………………. 17
TIMELINE ……………………………………………………………………………………………………….. 18
BUDGET/SPONSORS ………………………………………………………………………………………. 19
DISSEMNINATION TECHNIQUE……………………………………………………………………….. 20
REFERENCES…………………………………………………………………………………………………… 21
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INTRODUCTION
Sedimentary rocks are classified generally based on texture, cement and groups. These groups
can be subdivided into three such as detrital/clastic, biogenic and chemical sediments. These
sediments belong to the clastic group, which could be clean having silica cement, matrix rich-
greywacke and the arkosic type. The Benue Trough is a 1,000 km long, 50 to 150 km wide
intracontinental NE – SW trending rift depression in Nigeria. The basin (Benue Trough) is filled
with continental and marine sediments (about 6,500 m). The Benue Trough is divided into three
segments: the lower, middle and upper Benue regions.
The Upper Benue is an extensive sedimentary basin, with an area extent of about 203,000 km2
and occupies the upper reaches of the Benue valley. Its main drainage network comprises
numerous streams and rivers flowing into the River Benue from the north and south. The major
system includes the Gongola, Kilunga and Pai to the north and the Faro and Taraba from the
south of the River Benue. The ground slopes from the west, northeast and eastern areas into
the centre of the valley, but regionally sloping towards the southwest, the direction of flow of
the River Benue.
Bima sandstone is the name given to the continental Intecalaire in the Chad Basin and Upper
Benue Trough of Nigeria. It is the oldest sedimentary deposit in these regions. The composition
of Bima sandstone, mainly Arkose to quartz arenite and its depositional structures have
generated wide speculations as to the source and environment of deposition. This geologic
formation reaches hundreds of meters in thickness and is of significant interest in the Chad
basin as it is assumed to be the potential reservoir rock for petroleum storage and it is of hydro
geological significance in the upper Benue trough.
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LITERATURE REVIEW
Obiefuna G.I. et al (2010) Geochemical and Mineralogical Composition of Bima Sandstone
Deposit, Yola Area, NE Nigeria.
The results of the log of ratio of the major oxide groups indicate that Bima Sandstone of the
study area can be classified as greywacke, arkoses and lithic arenite including sub-greywacke
and protoquartzites. The abundant alkali values as shown by the relatively high log K2O/Na2O
ratio in most of the samples indicated immature sandstones whereas low alkali values in
other samples revealed mature sandstones. The enrichment of silica (quartz) over Al2O3 (log
SiO2/Al2O3<1.5) indicate that Bima Sandstone has undergone long period of transportation
and have been subjected to intense weathering resulting in the destruction of other minerals
especially plagioclase and potassium feldspars during transportation. Microscopic examination
of about sixteen slides (16) of Bima Sandstone under both plane and cross polars revealed the
following average mineralogical composition: quartz (65%) feldspars (14%), mica (9%), iron
oxide (5%), calcite (3%) further confirms quartz/lithic arenites and greywackes as some of the
predominant sedimentary rocks in the study area.
Bakari A., (2014) Granulometric Analysis of Bima Sandstone around Chekole in Gombe Sub-
Basin of the Upper Benue Trough, Nigeria.
The study investigates the grain size distribution of Bima sandstone formation exposed around
Chekole in North-eastern Nigeria and determines the condition of their deposition. The result of
the granulometric analysis indicates that the grain size of the Bima formation is continental in
origin which is dominated by coarse grains and some fine to medium grains which indicates an
evidence of change in depositional energy medium from moderate to high. Kurtosis values
ranged from Platykurtic to leptokurtic. The positive skewness values indicate fluvial process
under high energy condition. The sandstone has high storage capacities for hydrocarbon
accumulation, good aquifer characteristics and excellent economic value as aggregates for
construction.
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Obiora F.I. et al (2014) Depositional Environment of Bima Sandstone in Hinna Community in
Yamaltu/Deba Local Government Area of Gombe State, Nigeria and its Economic Importance in
Construction
The result of the sieve analysis indicates that the grain size, the formation ranges from fine to
medium then coarse grains which are evidence of change in depositional energy medium from
moderate to high. The positively skewness and bivariate plot show river origin also the grain
size proper proportions suggest that the sandstone has economic value. It can be mined for
engineering construction purpose thereby reduce cost compared to that of present day river
sand with a doubtable gradation for construction.
Saka A.O. (2012) Lithofacies Association in the Bima Sandstone of the Upper Benue Trough,
Nigeria
Facies association of the Bima Sandstone in the Upper Benue Trough reflects the tectonic
evolution of the basin. The concept of pull apart basin fits the rapidly changing alluvial facies
from coarser grained marginal to finer grained axial deposits. The stacking patterns of the
deposits are mainly of fan and fluvial channel sedimentation. While alluvial fan was deposited
as gravity and debris flow, a high sinuosity stream flow leading to a low sinuous form, probably
due to rejuvenation in the competence of the stream, was the basis of channel deposition of
the point/transverse bar as well as braided deposits in the basin. Four major Facies association
identified are: conglomeratic facies association – FA I; tabular sandstone facies association – FA
II; Soft sediment deformed beds FA III and medium bedded lenticular sandstone association- FA
IV.
LOCATION OF STUDY AREA
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The study area is located about 10 kilometers east of Hinna community in Gombe state which
corresponds to latitudes 10° 20’ and 10° 24’ North and longitudes 11° 37’ and 11° 40’ East. The
area falls in the (Gombe sub-basin) upper margins of the upper Benue Trough. It is
characterized by undulating terrain with few flat plains.
The climate is semi-arid with three distinct seasons: a long hot dry season from April to May.
Day time temperatures are in the range of 36 to 40°C and night time temperatures fall to 10 to
17°C. This is followed by a short rainy season from May to September with a daily minimum
temperature of 20°C and a maximum of 31°C with relative humidity of 40 to 60% and annual
rainfall from 860 to 900 mm. Finally, the cold (harmattan) season runs from October to March
when temperatures fall to about 20°C and a dry dusty wind blows from the Sahara desert
Figure 1 Map showing the location of study area
GEOLOGY STUDY OF THE AREA
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The Upper Benue Trough is made up of two arms, the Gongola Arm and the Yola Arm (Obaje,
2009). However, some authors have sub-divided the Upper Benue Trough to include a third
central Lau-Gombe sub-basin. In both arms of the basin, the Albian Bima Sandstone lies
unconformably on the Pre-Cambrian Basement. This formation was deposited under
continental conditions (fluvial, deltaic, lacustrine) and is made up of coarse to medium grained
sandstones, intercalated with carbonaceous clays, shales, and mudstones.
The Bima Sandstone is the most extensive earliest continental sediments deposited on the
floor of the entire basins of northeast Nigeria as a basal unit of the Cretaceous series soon after
crustal rifting. It lays discomformably on the basement complex. The first major study on the
formation was carried out by Carter, et al. (1963), based on the structural and Sedimentological
framework of the Lau sub-basin. The Bima Sandstone was subdivided by (Carter, et al., 1963)
into a Lower, Middle and Upper Bima. The Middle Bima is reported to be shaley in most parts
with some limestone intercalations and was assumed to be deposited under a more aqueous
anoxic condition (lacustrine, brief marine). Consequently, marine transgression episode caused
the deposition of Yolde, Dukul, Jessu, Sekule and Numanha sedimentary formations, which are
found in the Upper Benue Trough.
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Figure 2: Geological map of the Upper Benue Trough. 1, quaternary alluvium: 2, tertiary to
recent volcanism: 3, kerri kerri formation: 4, Gombe sandstone: 5, pindiga formation: 6, yolde
formation: 7, Bima sandstone: 8, burashika group (Mesozoic volcanism): 9, granitoids
precambrian (modified after Maurin et al., 1985).
Stratigraphic Units of the Bima Sandstone
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The Bima Sandstone is dominantly a quartz arenite occupying the base of the Cretaceous
succession in both the Upper Benue Trough and the Borno basin of Nigeria. The sediments
were mainly derived from juxtaposed basement suites of older granite and gneisses which were
subjected to humid conditions that accelerated the weathering processes. Despite the
dominance of quartz arenite as the main lithology, the field relationships of the beds made it
possible to differentiate the formation into three members; the Lower Bima (Bima – 1) the
Middle Bima (Bima – 2) and the Upper Bima (Bima – 3) (Carter, et al., 1963; Allix, 1983).
The Lower Bima was directly affected with the tectonic events (Guiraud, 1993) as large clasts
with muddy matrix were straddled as sediments within the fractured horst and graben of the
marginal rift structure. The unit is revealed at the exposed core of Lamurde anticline consisting
of shale intercalated with Feldspathic and calcareous sandstone (Carter, et al., 1963). The
middle and upper Bima beds overstep the lower Bima syn-rift deposits and in some places the
marginal horst of the rifted basement (Guiraud, 1990) (Figure 3). The clasts of the middle Bima
are coarse to medium grained with well marked pebbly lag deposits at the base of successive
beds while the upper Bima sediments are mainly of medium to fine grained clasts.
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Figure 3: Schematic Diagram of Lithostratigraphic Sequences of Bima Sandstone in Relation to
the Basement (Guiraud, 1990)
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STATEMENT OF PROBLEM
Previous studies in this area have investigated grain size distribution; geochemistry and geology
of sandstone formation exposed around Chekole in North-eastern Nigeria and determined the
condition of their deposition.
This proposed research is therefore expected to focus on Granulometric and Heavy mineral
analysis of sandstone in Hinna community.
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JUSTIFICATION
The knowledge of particle size distribution and the assemblages of heavy minerals in
Sedimentary rocks particularly in the earth crust make it possible to effectively locate and use
essential minerals to predict their dispersal pattern when they re-enter the natural
environment and information about the source of the sediment, provenance of the material as
well as the environment of deposition and mineral composition of Bima sandstone.
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AIM & OBJECTIVES
The aim is to provide a better understanding of the petrological characteristics of the
sedimentary environment.
OBJECTIVES:
Investigate the grain size distribution of the Bima Formation on the basis of their
physical characteristics
Determine the conditions of the deposition.
Paleoenvironment Reconstruction
14. 14
METHODOLOGY
A total number of twenty sandstone samples were collected randomly at different locations
from exposed Bima Sandstone deposits. Twenty samples were subjected to grain size analyses
out of which ten (10) of the finest residues were randomly selected for heavy mineral analysis.
The mineralogical analyses was carried out petrographically with the prepared thin sections
and viewed under both plane and cross polarized microscope in Department of Geology of the
University of Ilorin Nigeria in May to June 2015.
LABORATORY ANALYSIS
In the case of grain size analysis (granulometric); the samples will be effectively disaggregated
by squeezing them between fingers and paper sheets. The sand samples will be observed under
the binocular microscope in order to view the proportion of aggregated sands. A weight of
100gm will be obtained using a weight balance as a measuring instrument. Sieving analysis will
be achieved by using a sieve shaker of nine sieves agitating for about 10min. The sieve sizes to
be used for this operation are as follows; 4.00mm, 2.36mm, 1.60mm, 1.00mm, 0.50mm,
0.30mm, 0.25mm, 0.112mm, 0.09mm, 0.063mm, <0.0063mm. The corrected weight of each
fraction will be used to calculate individual percentage. Each cumulative percentage will be
obtained as a percentage of the cumulative of the cumulative corrected weight to the total
corrected weight. The grain size of the 5th, 16th, 25th, 50th, 75th, 84th and 95th percentiles
will be obtained from each cumulative curve drawn. These are used to calculate statistical
parameters for the Graphic Mean (M), Standard Deviation (sorting) (SD), Graphic Kurtosis (K)
and Graphic Skewness (SK) based on (Folk et al 1957) as follows:
Graphic Mean (M) = Ø16+Ø50+Ø84
3
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Standard Deviation (Sorting) (SD) = Ø84-Ø16 + Ø95- Ø5
4 6.6
Graphic Kurtosis (K) =Ø95- Ø5
2.44(Ø75- Ø25)
Graphic Skewness (SK) = (Ø84+ Ø16-2 Ø50) + (Ø95+ Ø5-2Ø50)
2(Ø84- Ø16) 2(Ø95- Ø5)
HEAVY MINERAL ANALYSIS
Ten samples will be selected from the twenty samples used for sieve analysis.
The prepared slides will be examined petrographically for non-opaque heavy minerals and on
reflected light for opaque heavy minerals. Identification of mineral type is based on optical
characteristics such as color, pleochroism, absorption, relief, extinction, and birefringence;
others are size, crystal form, and elongation. The “ZTR” index which is a quantitative definition
of mineral assemblage is calculated using the percentage of the combined Zircon, Tourmaline
and Rutile grains for each sample according to the formula below.
ZTR index = ZIRCON + TOURMALINE + RUTILE
TOTAL NO. OF NON OPAQUE HEAVY MINERALS
This formula is referred to as Hubert’s (1962) scheme. The calculated index is expressed in
percentage to ascertain the mineralogical maturity of the sediment.
Accordingly, ZTR <75% implies immature to sub mature sediments and ZTR >75% indicates
mineralogically matured sediments
.
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EXPECTED RESULT
From the analyses carried out, we will be able to deduce the following:
Energy of the Depositional Environment
Maturity and Transportational History of the sediment.
To determine the Hydrocarbon potential of the proposed area.
Source prediction through correlation.
VALUE ADDITION
From the result gotten,
Granulometric will help in paleoenvironmental reconstruction of Bima Sandstone and
also evaluate the Hydro-geological potential of the formation.
By carrying out Heavy minerals analysis, we will be able to determine if the Minerals are
commercial thereby developing the community industrially.
20. 20
REFERENCES
Allix P., (1983), “Environments Mezosoique de la partie nord-orientale du fosse de la Benoue
(Nigeria). Stratigraphie- Sedimentologie. Evolution dynamique. These 3emecycle.” Trav. Lab.
Sci. Terre. Marseille: St-Jerome, France. 21. 200p.
Bakari A., (2014), Granulometric Analysis of Bima Sandstone around Chekole in Gombe Sub-
Basin of the Upper Benue Trough, Nigeria, international journal of scientific & technology
research volume 3, issue 9.
Carter J.D., W. Barber, E.A. Tait, and G.P. Jones. (1963), “The Geology of Part of Adamawa,
Bauchi and Borno Provinces in Northeastern Nigeria”. Bull. of Geol. Surv. of Nigeria. 30:109.
Folk R.L, Ward W.C., (1957). Brazos river bar: a study in the significance of grain size
parameters. J. Sediment petrol., 27: 3 – 26.
Guiraud M., (1990), “Tectono-Sedimentary Frameworks of the Early Cretaceous Continental
Bima Formation (Upper Benue Trough, NE Nigeria)”. Jour. of African Earth Sciences. 10:341-353.
Guiraud M., (1993), “Late Jurassic Riftng- Early Cretaceous Rifting and Late Cretaceous
Transpressional Inversion in the Upper Benue Basin (in Nigeria)”. Bull. Centres Rech. Explor.-
Prod. Elf Aquataine. 12(1):29-128.
Hubert J.T., (1962). Zircon-tourmaline-rutile maturity index and interdependence of the
composition of heavy minerals assemblages with the gross composition and texture of
sandstones. J. Sed pet. 32:440–450.
Maurin J.C., Benkhelil J., Robineau B (1985), Fault rocks of the Kaltungo Lineament
(Northeastern Nigeria) and their relationship with the Benue Trough. J. Geol. Soc. London
143:587-599.
Obaje N.G., (2009), Geology and Mineral Resources of Nigeria‖. Springer, Berlin, London, pp:
69-72, 2009.
Obiefuna G.I., and Orazulike D.M. (2010), Geochemical and Mineralogical Composition of Bima
Sandstone Deposit, Yola Area, NE Nigeria, Research Journal of Environmental and Earth
Sciences 3(2): 95-102.
