The Messinian (Upper Miocene) is characterized at the level of its marginal basins by the development of numerous carbonate platforms. This study concerns the Messinian platform of the Boukadir region in the south of the Chelif Basin in Algeria. It is composed of a lower prograding rimmed platform and an upper aggradational homoclinal ramp resting upon the Tortonian–Lower Messinian Blue Marl Formation, and its thickness reaches ~280 m in the Chelif Basin. The upper red-algae unit is uniform and subhorizontal with a minimum thickness of 90 m. Petrographic analysis of the upper ramp reveals three different microfacies, characterized by Lithothamnium, foraminifera, high porosity, and a microsparitic matrix. MF1 is a packstone, MF2 a packstone/bindstone deposited above the fair-weather wave base and MF3 is a wackestone to packstone deposited below this level. The upper unit is made up entirely of autochthonous biogenic elements without significant external fluvial contribution. It was formed in a shallow marine environment, with very high productivity and a significant export of the sediments produced. This aggradation was followed by a rapid exhumation (regression) transforming all the aragonite into calcite. The platforms correspond to the T2 complex reef formation (6.7–5.95 Ma) documented on the other Messinian carbonate platforms in the South of the Alboran Sea that formed just before the Messinian Salinity Crisis.

To date, there have been few detailed studies regarding the impact of mining and metallogenic activities on solid fractions in the Azzaba mercurial district (northeast Algeria) despite its importance and global similarity with large Hg mines. To assess the degree, distribution, and sources of pollution, a physical inventory of apparent pollution was developed, and several samples of mining waste, process waste, sediment, and soil were collected on regional and local scales to determine the concentration of Hg and other metals according to their existing mineralogical association. Several physico-chemical parameters that are known to influence the pollution distribution are realized. The extremely high concentrations of all metals exceed all norms and predominantly characterize the metallurgic and mining areas; the metal concentrations significantly decrease at significant low distances from these sources. The geo-accumulation index, which is the most realistic assessment method, demonstrates that soils and sediments near waste dumps and abandoned Hg mines are extremely polluted by all analyzed metals. The pollution by these metals decreases significantly with distance, which indicates a limited dispersion. The results of a clustering analysis and an integrated pollution index suggest that waste dumps, which are composed of calcine and condensation wastes, are the main source of pollution. Correlations and principal component analysis reveal the important role of hosting carbonate rocks in limiting pollution and differentiating calcine wastes from condensation waste, which has an extremely high Hg concentration (˃1 %).

No abstract

No abstract

No abstract

No abstract

No abstract

Problem statement: Mercury mineralization occurred in Azzaba (north-eastern Algeria) as a part of mercurial Numidian belt, consists of numerous of Hg deposits (Koudiat Sma, Mrasma, Guenicha, Fendek, Ismail and Ras Elma). These deposits are hosted in a variety of lithologies including sandstone, limestone, breccias and conglomerate. The ores occur as cinnabar deposits in Ypresian-Lutetian formations. Although the quantity and type of information relating to mining operations within Azzaba remains insufficient and sparse an assessment of the impacts that mining and processing activities, have had or are likely to have, on water resources is required to describe the evidence of the origin and the extent Approach: 17 ground water samples were collected at different locations within the Hg mineralized area and analyzed to assess the source, degree and extent of the contamination. Results: The primary effect of mining is degradation of tens of kilometers of disturbed streams, thousands hectares of disturbed land including valuable ecosystems. chemical analysis showed that ground waters were also adversely affected by pollutants loading, the alluvial aquifer (composed primarily of silty sand and gravel) that serves as the primary source of drinking water for Menzel Ben Dishe, Es-sebt and Zaouia communities surrounding Ismail mercury complex shows high concentrations of Hg and other heavy metals. Conclusion: These high values were associated and controlled by mixed origin with similar contribution from anthropogenic and geoginic sources