“…Considering the diagram of Herron as shown in Figures 5 and 6, 37.5% of the studied samples were chemically classified as Subarkose (the sample from Northern Akwa AN1 to AN6 and from Youpoue-Bamenda YB2 and YB4 …), 12.5% as Fe-sand (sand from Village V1 and V2, and from Bonaberi Bonamikano BB3), and 25% as Sublitharenite (sand sample from Bonaberi Bonamikano BB1, from Youpoue YO2 and YO3 and from Youpoue-Bamenda YB1 …). These results are further supported by low Al 2 O 3 /SiO 2 ratios that easily allowed the classification of some other samples; the remaining 25% are classified as quartz arenites (sand from Dibamba D2, from Youpoue-Bamenda YB2 and YB3 and Bois de Singe BS3 and BS4 …) (Pettijohn et al 1987; Anani et al 2013; Caridi et al 2015). Figure 4 The positive correlation between K 2 O and Al 2 O 3 : K 2 O broadly follow the trend of the positive correlation increasing as Al 2 O 3 increases, indicating that it is associated, in the samples, with micaceous and/or clay minerals. Figure 5 Chemical classification of analysed geological samples from Douala and surrounding areas based on a discrimination using log (SiO 2 /Al 2 O 3 ) and log (Fe 2 O 3 /K 2 O) values (Herron 1988).…”
This study aimed to determine the concentration of natural radionuclides, the chemical composition, and the geological provenance of sand samples from seven large quarries within the Douala Basin and surrounding locations within the Littoral Region of Cameroon along the Gulf of Guinea. The analyses were undertaken on a total of 24 samples, using both gamma-and X-ray spectrometry techniques. Gamma spectrometric results indicated that the samples from the study area contained amounts of natural radioactivity that are less than the globally agreed safe limits. X-ray fluorescence spectrometry yielded quantitative major, minor, and trace element concentrations that were used in tectonic discrimination diagrams, indicating that these sediments were deposited in a passive margin environment. These concentration and natural radionuclide radioactivity level data provide a reference database for this region of Cameroon as well as for the wider Gulf of Guinea.
“…Considering the diagram of Herron as shown in Figures 5 and 6, 37.5% of the studied samples were chemically classified as Subarkose (the sample from Northern Akwa AN1 to AN6 and from Youpoue-Bamenda YB2 and YB4 …), 12.5% as Fe-sand (sand from Village V1 and V2, and from Bonaberi Bonamikano BB3), and 25% as Sublitharenite (sand sample from Bonaberi Bonamikano BB1, from Youpoue YO2 and YO3 and from Youpoue-Bamenda YB1 …). These results are further supported by low Al 2 O 3 /SiO 2 ratios that easily allowed the classification of some other samples; the remaining 25% are classified as quartz arenites (sand from Dibamba D2, from Youpoue-Bamenda YB2 and YB3 and Bois de Singe BS3 and BS4 …) (Pettijohn et al 1987; Anani et al 2013; Caridi et al 2015). Figure 4 The positive correlation between K 2 O and Al 2 O 3 : K 2 O broadly follow the trend of the positive correlation increasing as Al 2 O 3 increases, indicating that it is associated, in the samples, with micaceous and/or clay minerals. Figure 5 Chemical classification of analysed geological samples from Douala and surrounding areas based on a discrimination using log (SiO 2 /Al 2 O 3 ) and log (Fe 2 O 3 /K 2 O) values (Herron 1988).…”
This study aimed to determine the concentration of natural radionuclides, the chemical composition, and the geological provenance of sand samples from seven large quarries within the Douala Basin and surrounding locations within the Littoral Region of Cameroon along the Gulf of Guinea. The analyses were undertaken on a total of 24 samples, using both gamma-and X-ray spectrometry techniques. Gamma spectrometric results indicated that the samples from the study area contained amounts of natural radioactivity that are less than the globally agreed safe limits. X-ray fluorescence spectrometry yielded quantitative major, minor, and trace element concentrations that were used in tectonic discrimination diagrams, indicating that these sediments were deposited in a passive margin environment. These concentration and natural radionuclide radioactivity level data provide a reference database for this region of Cameroon as well as for the wider Gulf of Guinea.
“…5c). On the other hand, the diagram proposed by Pettijohn et al (1987) shows that inspected rocks are scattered in the fields of greywacke, litharenite and arkose (Fig. 5d).…”
Section: Methodsmentioning
confidence: 87%
“… Figure 5. Geochemical characteristics of the studied metasedimentary rocks from the Kamieniec Metamorphic Belt and the Doboszowice Metamorphic Complex. (a–d) Classification diagrams after (a) Hasterok et al (2018), (b) Wimmenauer (1984), (c) Herron (1988) and (d) Pettijohn et al (1987). (c, d) Upper continental crust (UCC)-normalized major element pattern for investigated samples from the Kamieniec Metamorphic Belt and the Doboszowice Metamorphic Complex.…”
The Kamieniec Metamorphic Belt (KMB) and the Doboszowice Metamorphic Complex (DMC) expose a fragment of the pre-Variscan volcano-sedimentary cover preserved in the Fore-Sudetic Block in the NE part of the Bohemian Massif. We present the age of detrital and magmatic zircon grains and the bulk rock chemical composition of rock samples from the KMB and the DMC to better understand the evolution of the early Palaeozoic Gondwana margin. The zircon age spectra were acquired by U–Pb LA–ICP–MS dating and represent two groups that differ by maximum depositional age (MDA). The paragneiss from the DMC displays the MDA at 456 Ma, whereas the mica shist from the KMB displays the MDA at 529 Ma. Older age peaks in both groups of samples are represented by the Neoproterozoic and less frequent the Paleoproterozoic and Archean. The data presented indicate that the rock successions were sourced from the Cadomian orogen and deposited in the basins that developed on the Gondwana margin. Our results support the suggestion that the crystalline basement in the eastern part of the Fore-Sudetic Block has an affinity to the Trans-Saharan Belt or West African Craton and was part of a Gondwana shelf. The final stage of evolution of the studied successions was related to the Variscan thermal overprint. Based on presented data, we support the idea that the suture separating the Brunovistulian domain from the rest of the Gondwana-derived terranes is not related to the closure of the Rheic Ocean and represents a local feature.
“…The Na/K molar ratio indicates the extent of chemical weathering of plagioclase. Plagioclase is rich in Na, especially compared to potassium feldspar, which is rich in K. Plagioclase undergoes a higher rate weathering compared to potassium feldspar 10 , 35 , resulting in an inverse relationship between chemical weathering intensity and the Na/K molar ratio 39 .…”
Topography is a critical factor that determines the characteristics of regional soil formation. Small-scale topographic changes are referred to microtopographies. In hilly mountainous regions, the redistribution of water and soil materials caused by microtopography is the main factor affecting the spatial heterogeneity of soil and the utilization of land resources. In this study, the influence of microtopography on pedogenesis was investigated using soil samples formed from mudstones with lacustrine facies deposition in the middle of the Sichuan Basin. Soil profiles were sampled along the slopes at the summit, shoulder, backslope, footslope, and toeslope positions. The morphological, physicochemical, and geochemical attributes of profiles were analyzed. The results showed that from the summit to the toeslope, soil thickness increased significantly and profile configuration changed from A–C to A–B–C. The total contents of Ca and Na decreased at the summit, backslope, and footslope, while the total contents of Al, Fe and Mg showed an opposite trend. On the summit and shoulder of the hillslope, weathered materials were transported away by gravity and surface erosion, exposing new rocks. As a result, soil development in these areas was relatively weak. In flat areas such as the footslope and toeslope with sufficient water conditions, the addition of weathered components and the prolonged contact between water, soil, and sediment led to further chemical weathering, resulting in highly developed characteristics. Microtopography may influence physicochemical properties, chemical weathering, and redistribution of water and materials, causing variations in pedogenic characteristics at different slope positions.
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