Geochronology and palaeoclimatic context of submerged siliciclastic beachrock formation in the western Mediterranean Sea

This article describes the geomorphological and petrological characteristics of 19 submerged beachrocks located on the north Catalan coast (western Mediterranean Sea). Their length ranges between 8 and 1039 m, their width between 1.5 and 86.5 m and their thickness between 0.4 and 3.25 m. They are siliciclastic beachrocks consisting of well-rounded gravels with a very coarse sand matrix, and they have a low proportion of bioclasts (<1%). Cementation occurred in the swash zone and adjacent foreshore due to the precipitation of high magnesium calcite. From absolute dates (14C and optically stimulated luminescence) and anthropic artifacts, three phases of formation attributable to the Late Holocene were identified. Phase I corresponds to the warm and humid Roman Period and was recorded at a level below -3.75 m mean sea level (MSL). Phase II corresponds to the warm and arid Medieval Climate Anomaly and was recorded at +0.25 m to -2.5 m MSL. Phase III corresponds to the Little Ice Age and Industrial Period and was recorded at levels ranging from +0.5 m to -3.0 m MSL. Good temporal correspondence between the chronology of the cementation phases and warm and/or dry palaeoclimatic conditions can be established.

Mg/Ca Ratios in Synthetic Low-Magnesium Calcite: An Experimental Investigation

The work presented sought to determine the effects of Mg/Ca ratios in solution have on Mg partitioning (KMg) between precipitated abiotic low-Mg calcite and solution. Experiments were set up so that Mg/Ca in precipitated abiotic calcite would match the Mg/Ca in planktonic foraminifera. This research intended to investigate the effect of Mg/Ca(Fluid) on KMg when the molar value of Mg/Ca(Fluid) was below 0.5, which is below the previously reported Mg/Ca range. The values of pH, salinity, and aqueous Mg/Ca were monitored during calcite precipitation, and Mg/Ca of calcite was determined at the end of experiments. Partition coefficients of Mg were evaluated as a ratio of Mg/Ca in calcite to the averaged ratio of aqueous Mg/Ca for each experiment.

The Use of Limestones Built of Carbonate Phases with Increased Mg Content in Processes of Flue Gas Desulfurization

The purpose of this article was to present the theory of the possibility of using limestone sorbents containing carbonate minerals with increased Mg content in processes of flue gas desulfurization in power stations. Data obtained as a result of the conducted research show that the analyzed Triassic (Muschelkalk) limestones of the south-west part of Poland are built of the following carbonate minerals: low magnesium calcite, high magnesium calcite, dolomite and huntite. These carbonate minerals are characterized by various magnesium contents. The increased content of magnesium in the sorbent has a positive effect on the technological process of flue gas desulfurization using the dry method, especially in the case of desulfurization with the application of Fluidized Bed Reactors. The positive influence of magnesium’s presence in sorbent in the desulfurization process is connected with the decarbonization of carbonate phases with magnesium at temperatures similar to the dolomite decarbonization temperatures, which are, thus, lower than typical for low magnesium calcite. The process would be easier because the structure of a solid solution containing magnesium ions, with a smaller ion radius to calcium ions, is unstable and the decomposition of these phases runs easier and faster. Therefore, the desulfurization process starts earlier and is more effective.

Trace Elements and REY in the Muschelkalk Limestones of the Opole Silesia in Poland

The results of researches of the selected trace elements: Ti, Sr, Ba, Zn, and also Cr, Ni, Cu, Zr, Mo, Pb, Rb, Mn, Na, K, P, Y and REE (REY) content were presented in this article. The elements were measured in the carbonate minerals of Muschelkalk (Middle Triassic) limestones of the Opole Silesia in Poland, using two methods: ICP MS spectrometry and X-ray fluorescence. These methods are characterized by very high precision and sensitivity of measurements. The results of researches show that the content of analyzed trace elements varies in from value below 1 ppm up to some hundreds ppm. However, the highest contents were measured for strontium and barium, elements characteristic for aragonite carbonate phase which is transformed such as high-Mg calcite into low magnesium calcite during diagenesis. So as Sr and Ba indicate the presence of aragonite in the primary carbonate material. The other trace elements probably form substitutions in clay or carbonate minerals. Some of trace elements such as Zn, Pb, Cu, Mo, Ni may also be associated with sulfide minerals and Ti, Cr, Mn, with oxides. Some measured REY elements- Ce, Nd, Sm, Gd, Dy, Er and Y are found in the rocks in very small quantities. So their content is really very low. It varies in from value below 1 ppm up to 6 ppm. REY usually substitute Ca ions in calcite.

HÖVSAN AERASİYA STANSİYASINDA TEXNOLOJİ PROSES ZAMANI ƏMƏLƏ GƏLƏN İZAFİ LİLİN TƏDQİQİ

hovsan Aeration Station provides treatment and processing of wastewater in baku. The amount of annual sludge here reaches 2 million cubic meters. These sludges contain complex multicomponent substances of organic and mineral origin. Taking this into consideration, we analyzed surplus sludge that generated during the technological process at hovsan Aeration Station. The studied surplus sample is a substance that is thickened in the mechanical workshop of the station, and then the substances are dehydrated in a centrifuge. They consist of a complex polydisperse system. The study of surplus sludge formed during the technological process at hovsan aeration station revealed that the main component of sludge consists of organic substances. The mineralogical composition is dominated by silicon dioxide and magnesium calcite. Keywords: wastewater, surplus sludge, mineral service, organic matter

Palaeozoic stromatoporoid diagenesis: a synthesis

Palaeozoic stromatoporoids, throughout their 100-million + year history (Middle Ordovician to Late Devonian and rare Carboniferous), are better preserved than originally aragonite molluscs, but less well-preserved than low magnesium-calcite brachiopods, bryozoans, trilobites and corals. However, the original mineralogy of stromatoporoids remains unresolved, and details of their diagenesis are patchy. This study of approximately 2000 stromatoporoids and the literature recognises three diagenetic stages, applicable throughout their geological history. Timing of processes may vary in and between stages; some components are not always present. Stage 1, on or just below sediment surface, comprises the following: micrite filling of upper gallery space after death, then filling of any remaining space by non-ferroan then ferroan calcite in decreasing oxygen of pore-waters; partial lithification of associated sediment from which stromatoporoids may be exhumed and redeposited, evidence of general early lithification of middle Palaeozoic shallow-marine carbonates; microdolomite formation, with the Mg interpreted to have been derived from original high-Mg calcite (HMC) mineralogy (likely overlaps Stage 2). Stage 2, short distance below sediment surface, comprising the following: fabric-retentive recrystallisation (FRR) of stromatoporoid skeletons forming fabric-retentive irregular calcite (FRIC), mostly orientated normal to growth layers, best seen in cross-polarised light. FRIC stops at stromatoporoid margins in contact with sediment and bioclasts. FRIC geometry varies, indicating some taxonomic control. Evidence that FRIC formed early in diagenetic history includes syntaxial continuation of FRIC into some sub-stromatoporoid cavities (Type 1 cement), although others were pre-occupied by early cement fills (Type 2 cement) formed before FRR, preventing syntaxial continuation of FRIC into cavities. Likely contemporaneous with FRIC formation, stromatoporoids in argillaceous micrites drew carbonate from adjacent sediment during reorganisation of argillaceous micrite into limestone–marl rhythms that are also early diagenetic. Stage 3, largely shallow burial, comprises the following: dissolution and silicification, but these may have occurred earlier in stromatoporoid diagenetic histories (more data required); burial pressure dissolution forming stylolites.