Journal of Geosciences and Geomatics

The aim of seismic data processing is to obtain accurate image of the subsurface which can be interpreted in terms of subsurface structures favourable to hydrocarbon accumulation. Multiples destructively interfere with primary reflections and their removal from reflection seismograms has been a longstanding problem to seismic processing geophysicists. If not eliminated, their presence could make seismic data interpretation difficult and lead to erroneous results. In this study, an attempt was successfully made to eliminate water bottom multiples by application of a specially derived parabolic radon filter on a 3D streamer seismic dataset acquired from offshore Niger Delta with the objective of improving the quality of the seismic data. Comparison of CMP gathers before and after application of the radon filter shows significant improvement in data quality which, if stacked, would create a volume more representative of the subsurface structures.

Journal of Geosciences and Geomatics. 2014, 2(4), 172-177. DOI: 10.12691/jgg-2-4-5
Pub. Date: September 03, 2014

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Support Vector Machines Based-Modeling of Land Suitability Analysis for Rainfed Agriculture

by Fereydoon Sarmadian, Ali Keshavarzi, Azin Rooien, Ghavamuddin Zahedi, Hossein Javadikia and Munawar Iqbal

Original Research

Soil evaluation plays important role in the sustainable agriculture development. Based on the value of several soil and environment indicators, the agricultural land evaluation methodology is applied to land mapping units in order to compute the suitability index. This index characterizes these land-mapping units. However, there are different methodologies which have been reviewed for land capability and suitability evaluation. In the present study, the potential use of support vector machines (SVMs) algorithm was evaluated for land suitability analysis for rainfed wheat based on FAO land evaluation frameworks (FAO, 1976, 1983, 1985) and the proposed method by Sys et al. (1991). The study area was divided into thirteen land units (with thirty two representative soil profiles) and ten land characteristics including climatic (precipitation, temperature), topographic (relief and slope) and soil-related (texture, CaCO₃, OC, coarse fragment, pH, gypsum) parameters were considered to be relevant to rainfed wheat. In this study economic factors have been excluded and moderate management has been assumed. The data points were divided by randomization technique and 80% data was selected to train the model and the remaining 20% was used to test the model. The Root Mean Square Error (RMSE) and coefficient of determination (R²) were used as evaluation criteria. The results showed that the corresponding values for RMSE and R²between the measured and predicted land suitability indices using the SVMs model were 3.72 and 0.84 respectively. Moreover, the most important limiting factors for rainfed wheat cultivation are climatic and topographic conditions, and 84.38% of total lands are classified as S₂ class (moderately suitable) while the remaining 15.62% are classified as S₃ class (marginally suitable). It appears that SVMs approach could be a suitable alternative to performance of land suitability scenarios.

Journal of Geosciences and Geomatics. 2014, 2(4), 165-171. DOI: 10.12691/jgg-2-4-4
Pub. Date: August 26, 2014

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Paleoproterozoic Synkinematic Magnesian High-K Magmatism from the Tamkoro-Bossangoa Massif, along the Bossangoa-Bossembele Shear Zone in North-Western Central African Republic

by P.E.Y. Danguene, T. Ngnotue, S. Ganno, J. Biandja, B. Kankeu and J.P. Nzenti

Original Research

The magnesian high-K calc-alkaline intrusive of the Tamkoro-Bossangoa Massif, North Western Central African Republic, were synkinematically emplaced in a sinistral strike-slip shear zone of Paleoproterozoic age. The rock sequences consist of orthogneisses with abundant coarse- to medium-grained quartz monzodiorite, quartz diorite and medium- to fine-grained biotite granite composition and cover a range of about 55 to 76 wt.-% SiO₂. They display characteristics of shoshonitic and high-K calc-alkaline series. Quartz monzodiorite and quartz diorite are metaluminous, whereas granite is moderately peraluminous (1≤ A/CNK ≤ 1.1) and plot in the field of I-type granitoids. Major and trace element composition of the granitoids indicate that the source materials were derived from different crustal protoliths. Major and trace element composition are consistent with the magmatism which may have involved remelting of (1) a composite metagreywackes protolith in the upper crust and (2) amphibolitised high-K calc-alkaline basaltic andesites in the central domain of the NEFB (North Equatorial Fold Belt). SHRIMP zircon and titanite dating of granitic rocks gives a magmatic zircon and titanite age of 2069 ± 9.6 Ma and 2063 ± 28 Ma respectively, a metamorphic age of 500 Ma and 597 Ma. The plutonic rocks of Tamkoro-Bossangoa area resemble other Paleoproterozoic high-K calc-alkaline syntectonic plutons in western and central . They also display strong similarities with high-K calc-alkaline plutons of eastern and of the in NE Brazil.

Journal of Geosciences and Geomatics. 2014, 2(4), 151-164. DOI: 10.12691/jgg-2-4-3
Pub. Date: July 15, 2014

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Geomorphology and Land Use Mapping of Northern Part of Rangpur District, Bangladesh

by Md. Saidul Islam, Abu Reza Md. Towfiqul Islam, Firosur Rahman, Farid Ahmed and Md. Nazwanul Haque

Original Research

The study area selected for the present research work was Kaunia upazila of northern part of Rangpur district, Bangladesh located between 8918′0′′E to 8930′0′′E longitude and 2542′0′′N to 2550′0′′N latitude. The aim of the study was to identified geomorphic unit and prepare geomorphic and land use map with the help of remotely sensed data. Remotely sense data provide a synoptic view of landscape on images. Geomorphic units were identified on the basis of tone, texture, size, shape, color and extract the precise information from the Landsat TM (FCC) images. Landforms were mainly active channel deposits, abandon channel deposits, natural levee deposits, flood plain deposits and flood basin deposits in the study area. From these geomorphic units together with land use were mapped using SPOT (band 4) panchromatic satellite image with visual interpretation technique along with field observation. The land use mapping will help to provide geo-scientific information for future development plan. Remotely sense data recommend identifying, evaluating and time-costing effective technique to fulfill the study objectives.

Journal of Geosciences and Geomatics. 2014, 2(4), 145-150. DOI: 10.12691/jgg-2-4-2
Pub. Date: July 09, 2014

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Platform Carbonates Distribution in the Carboniferous of Iran

by Kaveh Khaksar and Keyvan Khaksar

Original Research

In the Lower Carboniferous, the Iranian Platform represented the area of marine sedimentation. Carboniferous sequences of the Baluchestan Basin, Central Iran and Alborz are correlated. Distribution of corals in the Lower Carboniferous of Iran is influenced by both regional and world transgression and regression episodes. Tournaisian- Middle Serpukhovian marine deposits are well-developed and rich in fossil corals in the Alborz, and Baluchestan. They are extended from southeast to northwest in the area of Lower Carboniferous deposition. In the Middle Serpukhovian-Gzhelian marine sedimentation was restricted to the East Iran (Tabas area). However, fossil evidence suggests Late Carboniferous age only for part of the Tabas area sequence.

Journal of Geosciences and Geomatics. 2014, 2(4), 139-144. DOI: 10.12691/jgg-2-4-1
Pub. Date: June 30, 2014

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