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Trace and Rare Earth Element Geochemical
Fingerprints on the Petrogenesis and Geotectonics of the
Enderbite-Adamellite-Granite Complex in Parts of Bansara (Sheet 304 NE and SE), Southeastern Nigeria
--Egesi N, --Ukaegbu V U
Bansara area is underlain by rugged topographic features of the Pan-African
high-grade metagreywacke-pelite sequence, metagranites and post-Pan-African
rift-generated enderbites, adamellites and granites. Rock samples of the igneous rocks were analyzed
for trace and rare earth element behavior using ICP-MS technique with a view to document their
petrogenetic and geotectonic characteristics. Several variation diagrams and parameters applied to the analytical
data indicated linear evolutionary trend from a common source. Trace element behaviors, in particular,
strongly suggested that differentiation was the prime cause for their chemical variations. REE behavior of the
rocks showed distinctive patterns from highly fractionated patterns with pronounced negative Eu anomaly in
the granites and adamellites to less fractionated patterns with moderate negative Eu anomaly in the
enderbites. The REE abundance and patterns further reflected mantle to crustal petrogenetic variation trend of
different rock suites in the area. The granites and adamellites probably formed at crustal level from the
differentiating enderbitic melt of mantle origin in a setting dominated by rifting and post-collision uplift probably due
to mantle plume and mantle-crust mingling that characterized the geothermal history of the area in the
post-Pan-African.
© 2010 IUP. All Rights Reserved.
Sequence Stratigraphy of the Surma Group,
Sitakund Anticline, Chittagong, Bangladesh
--Mrinal Kanti Roy, --Md. Moniruzzaman,
--Md. Masidul Haque,
--Partha Jit Roy,
--Sudip Saha, --Md. Azizul Alam
The Surma group of rocks are well-exposed in the steeper and faulted western
flank as well as gentle and wider eastern flank of the asymmetric doubly plunging
Sitakund anticline under the Chittagong district from Bariyadhala in the north to Barabkund in the
south, which trends regionally in the NNW-SSE directions. Lithostratigraphically, the Bhuban formation
consists of alternation yellow to yellowish gray medium to grained sandstone with black shale and siltstone, Boka
Bil formation constitutes the medium grained yellow to yellowish gray sandstone-siltstone with bluish gray
shale. Eleven facies have been identified with the lithosuccession of this group, which are grouped into
turbidite facies association, deep marine basin plain and tide-generated facies association. The sub facies
association of tide-dominated delta, estuarine, tidal creek/small estuarine and mud-dominated tidal flat constitute
the tide generated facies association. Five parasequences are delineated. The overall depositional
environments of the study area vary from deep marine to submarine fan in the Bhuban formation and tidal delta,
estuarine channel and tidal flat in the Boka Bil formation at various phases during deposition due to relative sea
level rise and fall, sediment supply and basin tectonics.
© 2010 IUP. All Rights Reserved.
An Analysis of Earthquake Focal Depths
in Africa (1900-2000)
--Ugwu Sylvester A,
--Onuoha K Mosto
Earthquakes result from the rapid release of stored elastic strain in the lithosphere, usually in the form
of sudden movement of portions of the earth's crust along faults. Earthquakes are classified as shallow focus
at depth less than 70 km, intermediate focus between 70 and 300 km and deep focus >300 km. The
objective of the study is to find the depth distribution of earthquakes focal depths in African lithosphere. It also
finds the relationship between the focal depths and the earthquake magnitudes. The analysis utilized all
available recorded earthquake focal depths and magnitudes in Africa from 1900-2000. The focal depths are
arranged into depth ranges of 0-5 km, 5-10 km, etc. Two subsurface depth zones, 5-10 km and 30-35 km, have
been identified as zones of concentration of earthquake focal depths in Africa. There is a decrease in
seismicity from a depth of 15-29 km. It was discovered that the lower crust and the upper mantle have the same
number of earthquake foci and this has rheological significance. The studies further revealed the independence
of earthquake magnitudes on the focal depths. The research also suggests that there may be two types of
earthquake return periods in Ethiopia, at every 55 and 32 years.
© 2010 IUP. All Rights Reserved.
Evaluation of Physicomechanical Properties of Granites
in Warangal District, AP, as Dimensional and
Decorative Stones
--G Prabhakar,
--Ishrath, --A P Siva Kumar
`Granite' is being indiscriminately and extensively exploited and quarried without a detailed study of
the physicomechanical and intrinsic properties of granites. As such, huge blocks of granites are being cut
and efforts are being made to export them. Since the business entrepreneurs are insisting on the database tag
to be attached with each block of granite that is being exploited and exported, the need to study
their physicomechanical properties has become important. As a followup to this observation, a study of the
working quarries of black granites (dolerties) and grey granites undertaken in Warangal district of Andhra
Pradesh, suggested their suitability as dimensional and decorative stones. The study evaluated the specific gravity
of the stones ranging from 2.64-2.95 with low porosity, compressive strength ranging between 585.33
and 1,930 kg/cm2 in dolerites, 750-1,150
kg/cm2 in granites and 400-1,600 kg/cm in granite gneisses,
and modulus elasticity ranging from 3.5-57 ´ 10
kg/cm2. The results are very much useful to evaluate
their suitability as dimensional and decorative stones.
© 2010 IUP. All Rights Reserved.
Environmental Control of Groundwater Resources
in Siliguri Subdivision of Darjeeling District, India
--Khondoker Emamul Haque,
--M M Jana
This paper deals with the detailed physicochemical characteristics of groundwater resources from
different lithological units in the Siliguri subdivision of Darjeeling district which have been evaluated on 18
parameters. The study reveals that groundwater is hard and contains more iron percentage than the permissible
limit. The concentrations of calcium, magnesium and fluoride ions are significantly lower than the safe
limits prescribed for drinking purpose, causing health hazards, such as cardiovascular problems,
gastrointestinal irritation, dental caries, respiratory disorders and spinal cord system diseases. The rapid soil erosion
and the associated runoff were caused by geomorphological conditions, deforestation due to shifting
cultivation, and climatic factors, which are probably responsible for the low concentration of groundwater.
© 2010 IUP. All Rights Reserved.
CBD 2010 Target: A Case Study of
Kolleru Wetland (Ramsar Site), India
Using Remote Sensing and GIS
--Chiranjibi Pattanaik, --S Narendra Prasad,
--Nidhi Nagabhatla, --S S Sellamuttu
Regular monitoring of wetlands is an essential element of management for `wise use'. Indeed, the
Ramsar convention requires routine monitoring in order to detect changes in the ecological character at listed
sites. However, there are few examples of monitoring of tropical wetlands on a sustained basis in the world. In
the present study, we quantified land use/land cover changes in the lone Ramsar site, the Kolleru
Wildlife Sanctuary of Andhra Pradesh, India between 1977 and 2007 using remote sensing and GIS techniques.
It was found that there was a significant increase in aquaculture farming (158.5 sq km) from 1977 to
2000, which put the habitat of flora and fauna in adverse conditions. The natural function of lake was
being restored after the demolition of fishponds ordered by the Honorable Supreme Court of India in 2006.
This study highlights the firsthand information to the user community after demolition, and offers
suggestions for the future conservation of the lake.We suggest that remote sensing and GIS tools have a significant role
in meeting the reported requirements for the CBD 2010 target.
© 2010 IUP. All Rights Reserved.
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