Geochemistry of Onshore Deposits From Rio-Del-Rey Sub-Basin of The Western Atlantic Margin of Cameroon (Coastal Basin, South West Cameroon): Provenance And Environments of Sedimentation

The Rio del Rey Basin belongs to the coastal basins of Cameroon with Cretaceous to Cenozoic deposits. The Cretaceous (Cenomanian and Campanian-Maastrichtian) and Cenozoic (Paleocene) sediments were studied using major and trace elements geochemistry associated with mineralogical data. The studied samples are mainly made up of Fe-shale and shale with rare intercalations of Fe-sand in the Cenomanian deposits, Fe-shale and shale in the Campanian-Maastrichtian deposits and sub-litharenite, Fe-sand, shale and Fe-shale in the Paleocene deposits. These samples contain high LREE/HREE ratios (9.27 -24.23), no to slight positive Eu anomalies (Eu/Eu*= 1.02 – 1.44), moderate to high Al2O3/TiO2 (10.42 – 112.93) ratio and their position in the Ce vs. La/Yb, Zr vs. TiO2 and La/Sc vs. Th/Co diagrams indicate that they derivate from mainly felsic associated with subordinate intermediate igneous rocks. The CIA (Chemical Index of Alteration; 61.69 – 92.76), PIA (Plagioclase Index of Alteration; 62.16 – 99.47), K2O/Na2O ratios (0.08 – 22.125) and Zr/Sc vs. Th/Sc diagram suggest the source rocks have experienced low to high recycling and weathering (Paleocene deposits), high chemical weathering (Campanian-Maastrichtian) and moderate to high chemical watering (Cenomanian deposits). The SiO2 vs. Al2O3 + K2O + Na2O plot suggests a predominant semi-arid to arid climate with periodically semi-humid climate during the Paleocene, attested by the evolution of the clay minerals composition with association of illite-chlorite/vermiculite/kaolinite in the Cenomanian sediments and periodic appearance of siderite in the Campanian-Maastrichtian and Paleocene deposits. The Sr/Ba (0.41 – 2) and U/Th (0.16 – 0.28) ratios indicate brackish to shallow marine environment of deposition. The Arc-Rift-Collision of two sets of high and low silica rocks and SiO2 vs. K2O/Na2O diagrams indicate a Collisional or Active Continental Margin tectonic setting similar as the Cretaceous (Lower Mundeck and Logbadjeck Formation) and Paleocene (Nkapa Formation) deposits from the Douala sub-basin, which could reflect the Precambian basement history linked to the Neoproterozoic orogeny.

Nanomaterials for subsurface application: study of particles retention in porous media

The ability to transport nanoparticles through porous media has interesting engineering applications, notably in reservoir capacity exploration and soil remediation. A series of core-flooding experiments were conducted for quantitative analysis of functionalized TiO2 nanoparticles transport through various porous media including calcite, dolomite, silica, and limestone rocks. The adsorption of surfactants on the rock surface and nanoparticle retention in pore walls were evaluated by chemical oxygen demand (COD) and UV–Vis spectroscopy. By applying TiO2 nanoparticles, 49.3 and 68.0 wt.% of surfactant adsorption reduction were observed in pore walls of dolomite and silica rock, respectively. Not surprisingly, the value of nanoparticle deposition for dolomite and silica rocks was near zero, implying that surfactant adsorption is proportional to nanoparticle deposition. On the other hand, surfactant adsorption was increased for other types of rock in presence of nanoparticles. 5.5, 13.5, and 22.4 wt.% of nanoparticle deposition was estimated for calcite, black and red limestone, respectively. By making a connection between physicochemical rock properties and nanoparticle deposition rates, we concluded that the surface roughness of rock has a significant influence on mechanical trapping and deposition of nanoparticles in pore-throats.

Heat Treatment

In archaeology, heat treatment is the intentional transformation of stone (normally sedimentary silica rocks) by fire to produce materials with improved fracture properties. It has been documented on all continents, from the Africa Middle Stone Age up to subrecent times. It was an important part of the Mediterranean Neolithic and it sporadically appeared in the Paleolithc and Mesolithic of Asia and Europe. It may have been part of the knowledge of people first colonizing North and South America, and it played an important role for toolmaking in the Australian Prehistory. In all these contexts, heat treatment was normally used to improve the quality of stone raw materials for tool knapping; especially its association with pressure flaking has been highlighted, but a few examples also document the quest of making tools with improved qualities (sharper cutting edges) and intentional segmentation of large blocks of raw material to produce smaller, better-usable modules (fire fracturing). Two categories of silica rocks were most often heat-treated throughout prehistory: relatively fine-grained marine chert or flint and more coarse-grained continental silcrete. The finding of stone heat treatment in archaeological contexts opens up several research questions on its role for toolmaking, its cognitive and social implications, and the investment it required. Important venues for research are, for example: Why did people heat-treat stone? What happens to stones when heated? How can heating be recognized? By what technical means were stones heated? Which cost did heat treatment represent for its instigators? Answering these questions allows light to be shed on archaeologically relevant processes like innovation, reinvention, convergence, or the advent of complexity. The methods needed to produce these answers, however, often stem from other fields such as physics, chemistry, mineralogy, or material sciences.

Study of Petrogenesis and Tectonomagmatic Environments of Eocene Calc-Alkaline Volcanic Units in South and Southeast of Beroni Village in Southwest Ardestan (Isfahan)

The study area is located in south and southeast of Beroni Village. It contains volcanic rocks including andesitic-basaltic, pyroxene-bearing andesite, andesite, dacite, rhyodacite, rhyolites and Eocene-Oligocene ignimbrites. The volcanic rocks are cut by an intrusive mass with great spreading in the region. According to lithological studies, the calc-alkaline magmas in continental margin arcs are comprised of mantle and fluid crust. The basic elements in the volcanic rocks were studied in terms of petrological indices. According to the results, the metaluminous rocks underwent crustal contamination. Due to chemical reactions between the hydrothermal solution and volcanic host rocks, hydrothermal solutions in volcanic rocks penetrate the surrounding silica rocks and thus some elements such as zinc and barium diffuse in the rocks. In addition, calcium, magnesium and iron have been drawn inwards from the surrounding rocks causing lateral segregation.