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Dallol area is located in Afar region of northeastern Ethiopia. From west to east, the geology of the area is characterized by: i) Neoproterozoic metavolcanics and metasediments, ii) Quaternary alluvial fan deposits and red beds, iii) a transitional zone of mud and salt mixture, and iv) evaporites, which consist of rock salt (commonly halite and potash) and sulfur/sulfides. The metavolcanic-sedimentary rocks of the area are sheared and locally affected by pervasive chloritization, silicification, and carbonatization as well as quartz-carbonate veining suggesting that it has a good potential for orogenic gold mineralization. The around 5 m thick alluvial sediments of Gehartu and Musely Fans are also favorable for the occurrence of placer gold deposits. This study reveals that industrial minerals such as kaolin and mica are also encountered in the Dallol area in addition to the already known sulfur and salt deposits. In surrounding areas of mount Dallol, hot springs of varying temperature and extent are being erupted forming semicircular to circular ponds. In this study, two types of hot springs, light-yellowish and yellowish brines are recognized which are contaminated with mud. Field observations show that both brines have indications for the presence of oil as sensed by greasy feelings. To know the general compositions of the hot springs and test the presence of liquid hydrocarbons, 8 water samples were collected and analyzed for major element contents, sulfide, sulfate and Total Organic Carbon (TOC) concentrations. The preliminary results show that TOC values are moderately low (94 to 902 ppm). Sulfate (19 to 60 ppm) and sulfide (27 to 111 ppm) concentrations are low except for one sample with higher concentrations for both complexes. Their low sulfide and sulfate content suggest that these compounds are converted into sulfur/sulfide by bacterial reduction of magmatic and/or sea water SO 2 or sulfate. Therefore, the Dallol hot springs are interpreted to be derived from heated groundwater mixed with sulfides/sulfates of magmatic and/or sea water origin. Although low, the up to 902 ppm TOC concentrations in the hydrothermal fluids could suggest the presence of hydrocarbon containing rocks at depth and/or fluid mixing with laterally and/or vertically migrating hydrocarbon fluids. Generally, the Dallol area contains huge metallic and non metallic resources, which warrant detailed exploration and further scientific study.

The research presented here investigates the reaction mechanism of wollastonite in situ mineral carbonation for carbon dioxide (CO2) sequestration. Because wollastonite contains high calcium (Ca) content, it was considered as a suitable feedstock in the mineral carbonation process. To evaluate the reaction mechanism of wollastonite for geological CO2 sequestration (GCS), a series of carbonation experiments were performed at a range of temperatures from 35 to 90 °C, pressures from 1500 to 4000 psi, and salinities from 0 to 90,000 mg/L NaCl. The kinetics batch modeling results were validated with carbonation experiments at the specific pressure and temperature of 1500 psi and 65 °C, respectively. The results showed that the dissolution of calcium increases with increment in pressure and salinity from 1500 to 4000 psi and 0 to 90000 mg/L NaCl, respectively. However, the calcium concentration decreases by 49%, as the reaction temperature increases from 35 to 90 °C. Besides, it is clear from the findings that the carbonation efficiency only shows a small difference (i.e., ±2%) for changing the pressure and salinity, whereas the carbonation efficiency was shown to be enhanced by 62% with increment in the reaction temperature. These findings can provide information about CO2 mineralization of calcium silicate at the GCS condition, which may enable us to predict the fate of the injected CO2, and its subsurface geochemical evolution during the CO2–fluid–rock interaction.

The Paleozoic stratigraphic record of Peninsular Malaysia, where many carbonate occurrences have been reported (Figure 1), is not an exception. These deposits encompass marine sedimentary successions ranging from the late Cambrian to early Permian (Foo, 1983;Lee, 2009). Complex tectonostratigraphic events of the Paleo-Tethys basins have been well documented

There is a recognized need for the determination of total organic carbon (TOC) as an essential factor in the evaluation of source rocks. In this study, the ∆LogR technique was coupled with logging curves of sonic, resistivity, spectral gamma-ray (SGR), and computed gamma-ray (CGR) to determine an accurate content of TOC in the Gadvan Formation. Multiple linear regression analysis was also applied to the ∆LogR technique. To this aim, 14 samples of the Gadvan Formation were taken from Wells B and C in the South Pars field and analyzed using Rock-Eval pyrolysis. Results from the ∆LogR technique and multiple linear regression analysis, well logs, and Rock-Eval were compared to calculate the accurate content of TOC in the Gadvan Formation. Geochemical data confirmed that the Gadvan Formation was a relatively poor source rock in the South Pars field, as average TOC and Tmax values of the samples were 0.79 and less than 430 °C, respectively. Also, the content of potassium (K < 0.1%) confirmed the origin of the source rock as a pure carbonate, whereas the low content of thorium (Th < 5 ppm) was indicative of the percentage of clays. There was a moderate content of uranium (U < 10 ppm), suggesting that the Gadvan Formation was not deposited in an excellent reducing environment to conserve the organic matter. Moreover, the results from the integration of the multiple linear regression model with SGR and CGR showed that the value of R2 was higher than the results obtained without SGR and CGR. Findings from this study could help the exploration and production team to determine the accurate content of TOC using the ∆LogR technique in association with logging curves.

The Palaeo‐Tethys is known to have diverged into several splays throughout East and South‐east Asia. Several researchers have widely studied the importance and geometries of the Palaeo‐Tethys' branches. Plate reconstruction geometries for the southern Palaeo‐Tethys splay suggest that the ocean either connects to the proto‐Pacific or dies out. We review and discuss the Late Palaeozoic to the Early Mesozoic lithologies attributed to the Palaeo‐Tethys, from the Himalayan Syntaxis in the north to the Bangka and Belitung islands in western Indonesia to the south. Relics of oceanic crust and deep‐sea sediments related to the main Palaeo‐Tethys Basin can be traced from the South China (Yunnan)‐Thailand border to Peninsular Malaysia. A sub‐parallel back‐arc suture exists in eastern Thailand in the north and vanishes towards the south at the latitude of the Gulf of Thailand. Towards the south of Peninsular Malaysia, the material that constitutes the suture zone of main Palaeo‐Tethys is found offshore in the Riau Archipelago, Indonesia, and has been extensively eroded. Thus, we rely on gravity signatures to extrapolate the extension of the structures to the Bangka and Belitung islands, which show only minor serpentine and pillow basalts occurrences along a line that curves towards Borneo. The metamorphic rocks associated with the suture zones range from high grade (gneiss) in Thailand to low grade (mica schist and minor amphibolite) in Peninsular Malaysia. The syn‐ and post‐collisional granitic bodies that form large batholiths in Thailand and Malaysia are comparatively smaller in Indonesia, particularly on Belitung Island, suggesting the lack of large underplating of the Sibumasu crust within the region. We interpret the stratigraphic and tectonic observations of the southern Palaeo‐Tethys to support the theory of the southward (present orientation) opening of a propagating oceanic basin from Devonian to Carboniferous, which began to close from the Permian to Triassic period.

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