Utilization of multispectral satellite images is an excellent approach in the reconnaissance stage of gold prospecting due to its high effectiveness and low cost. This research used Landsat 8 Remote Sensing data and Geographical Information System to identify, delineate and map hydrothermal alteration zone relating to gold pattern mineralization in Prestea Huni Valley District in the Western Region of Ghana. Principle Component Analysis (PCA), three band combinations, spectral rationing and Crosta techniques are used in this study. For three band combinations, bands 5, 4, 3 and 5, 6, 7 are used to map location of hydrothermal alterations. Band ratios (7/5and6/7), (6/5) and (4/2) are used to identify presence of clay, ferrous and iron oxide minerals respectively. Sabin's ratio 4/2, 6/7 and 6/5, Kaufmann ratio 7/5, 5/4 and 6/7, and 4/2, 6/7 and 5 are used to identify vegetation, outcrop and hydrothermal alterations respectively. Crosta and PCA techniques were used to suppress the interference of vegetation in delineating the alteration zones. Results revealed that the three band combinations and spectral ratioing clearly depicts hydrothermal deposit of ferrous minerals, clay and iron oxide minerals. PCA identifies presence of iron-oxide and hydroxyl minerals as bright pixels. The first three high order principal components (PC1, PC2 and PC3) of input spectral bands gave more than 98% of the spectral information. Thus, the results from satellite images an effective and efficient way of mapping hydrothermal alteration zones at regional scale. Contribution/Originality: This is one of the very few studies which have investigated to identify hydrothermally alteration relating to gold mineralization. The study documents how Satellite data and Remote Sensing and Geographical Information System techniques can be used to delineate hydrothermal alterations at regional scale at a reduced cost.
Contribution/Originality: This study documents that regolith environments have huge influence on surface gold expressions and anomaly definition. Regolith-based geochemical interpretation is effective to account for each regolithic effect. Each regolith type has equal tendency of hosting realistic anomaly when equal weight of importance is accorded to them. INTRODUCTIONIncessant climatic changes over the years have extensively affected most terrains in Ghana, predominantly the savannah areas and some tropical rainforests resulting in the present complex landforms (Arhin and Nude, 2009). The associated weathering processes and regolith landform evolutions post exploration challenges. Furthermore, these processes may co-exist with other geologic processes such as the deposition of post-mineralization materials to offset or obscure mineralization and impose exploration challenges (Arndt et al., 2017).
Cumulative residual analysis (CRA) Mann-Kendall and Sen's Slope tests Wavelet transform (WT) Principal component analysis (PCA) Remote sensing Ghana CHIRPS data.Precipitation variability evaluation assumes a vital part in water asset administration and rainfed agribusiness. In Ghana, rain gauge stations are poorly distributed and also, obtaining long time span of data is difficult due to data inconsistency, as a result remotely sensed precipitation products are largely used to complement ground gauge stations data for assessing climatic variability and water resource managements. In this study, Climate Hazards Group Infrared Precipitation with Station (CHIRPS) precipitation data from 1981-2016 and also utilizing Cumulative Residual Analysis (CRA), Mann-Kendall, Sen's Slope, Wavelet Transform (WT) and Principal Component Analysis (PCA). Results show that 1981, 1999, 2002 and 2013 were four noteworthy years with changes in precipitation. The Mann-Kendal and Sen's Slope demonstrate that 55.71% of UER indicated diminishing month to month precipitation with 27.34% critical patterns. Precipitation in April, May, and June demonstrated a diminishing pattern while July, August, and September showed an increasing trend during the 35 years' study period. Further investigation using Continuous Wavelet Transform indicated an annual variation significant. PCA uncovered that the spatial variability of precipitation in UER is extremely assorted, however greater part (33.76%) of the fluctuation is situated in the north-eastern part. Thus, the results from remotely sensed precipitation products an effective, efficient and cheap way of assessing top to the bottom comprehension of precipitation variation at regional level. Contribution/Originality: This study is one of very few studies which have investigated in the study area which applied new methods such as Cumulative residual analysis (CRA), Mann-Kendall and Sen's Slope tests, Wavelet transform (WT), Principal component analysis (PCA) on remotely sensed precipitation data to assess both spatial and temporal variability.
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