Stanienda-Pilecki KJ (2018), Magnesium calcite in Muschelkalk limestones of ...

ECB-ART-49951

Carbonates Evaporites 2018 Jan 01;334:801-821. doi: 10.1007/s13146-018-0437-y.

Show Gene links Show Anatomy links

Magnesium calcite in Muschelkalk limestones of the Polish part of the Germanic Basin.

Stanienda-Pilecki KJ .

???displayArticle.abstract???
Magnesium calcite, which is usually observed in many natural low-temperature environments, was identified in Triassic limestones of the Polish part of the Germanic Basin. The occurrence of unstable magnesium calcite in Triassic limestones is remarkable. High-Mg calcite was identified in all beds of the Muschelkalk Karchowice Formation: Lower Crinoidea Beds, Lower Biohermal Beds, Upper Crinoidea Beds and Upper Biohermal Beds. The general chemical formulas of magnesium calcite of mentioned unites are: (Ca0.87-0.80,Mg0.13-0.20)CO3, (Ca0.83-0.75,Mg0.17-0.25)CO3, (Ca0.81,Mg0.19)CO3, (Ca0.78-0.77,Mg0.22-0.23)CO3 respectively. This mineral originated probably during the early stage of diagenesis, during compaction of limestones deposited in a warm, shallow marine environment. Some amounts of magnesium come from high-Mg skeletons of marine organisms (such as echinoderms). Diagnenetic processes and the conditions in seawater, especially higher salinity, influence the preservation of high magnesium calcite in the Muschelkalk limestone of the Polish part of the Germanic Basin.

???displayArticle.pubmedLink??? 30524175
???displayArticle.pmcLink??? PMC6244636
???displayArticle.link??? Carbonates Evaporites

???attribute.lit??? ???displayArticles.show???

	Fig. 1. Geological map of the central part of Opole Silesia(After Niedźwiedzki 2000; Stanienda 2013; modified)
	Fig. 2. Lithostratigraphic profile of Muschelkalk sediments of the analyzed area. Diplopora Beds; Karchowice Beds (upper Biohermal limestones); Karchowice Beds (upper Crinoidea limestones); Karchowice Beds (lower Biohermal limestones); Karchowice Beds (lower Crinoidea limestones); Dziewkowice (Terebratula) Beds; Górażdże Beds; Gogolin Beds
	Fig. 3. Lithostratigraphic profile of the Karchowice Beds form the Tarnów Opolski Deposit. Karchowice Beds (upper Biohermal limestones); Karchowice Beds (upper Crinoidea limestones); Karchowice Beds (lower Biohermal limestones); Karchowice Beds (lower Crinoidea limestones)
	Fig. 4. A Microscopic view of lower Crinoidea limestone (sample 7)—limestone built of sparry mass, built mainly of calcite crystals and rhombohedral dolomite crystals. 1N, Magn. ×200 (Stanienda 2000, 2011). Cal, calcite phase; Dol, dolomite phase. B Microscopic view of lower Biohermal limestone (sample 2)—aggregates of coarse-grained calcite crystals and rhombohedral dolomite crystals in sparry rock mass. XN, Magn. ×100 (Stanienda 2000, 2011). Cal, calcite phase; Dol, dolomite phase. C Microscopic view of lower Biohermal limestone (sample 8)—bioclast filled with coarse-grained calcite, in some places also dolomite in microsparry orthochem cement built mainly of calcite crystals and in some areas of rhombohedral dolomite crystals. XN, Magn. ×100 (Stanienda 2000, 2011). Cal, calcite phase; Dol, dolomite phase. D Microscopic view of upper Crinoidea limestone (sample 15)—in the foreground bioclast (crinoid circular stem plate) in microsparry orthochem cement built of calcite. XN, Magn. ×100 (Stanienda 2000, 2011). Cal, calcite phase. E Microscopic view of upper Crinoidea limestone (sample 61)—on the right side vein filled with sparry calcite with visible rhombohedral cleavage. Apart from calcite crystals also rhombohedral dolomite crystals are visible in some places. XN, Magn. ×100 (Stanienda 2000, 2011). Cal, calcite phase; Dol, dolomite phase. F Microscopic view of upper Biohermal limestone (sample 41)—rhombohedral dolomite crystals dominate here. In some areas micro-sparry and micritic calcite is visible. XN, Magn. ×100 (Stanienda 2000, 2011). Cal, calcite phase; Dol, dolomite phase. G Microscopic view of upper Biohermal limestone (sample 57)—bioclast in sparry rock mass. In some places rhombohedral dolomite crystals are visible. XN, Magn. ×100 (Stanienda 2000, 2011). Cal, calcite phase; Dol, dolomite phase. H Microscopic view of upper Biohermal limestone (sample 64)—group of bioclasts cemented by sparry, in some areas of rock, syntaxial calcite. In some places rhombohedral dolomite crystals are visible. XN, Magn. ×100 (Stanienda 2000, 2011). Cal, calcite phase; Dol, dolomite phase
	Fig. 5. A BSE image of an lower Crinoidea limestone (sample 7) (Stanienda 2004, 2011). Magn. ×1500, 1–11-points of chemical analysis. Cal—low-Mg calcite; Mg-Cal—high-Mg calcite; Pr-Dol—protodolomite. B BSE image of an Lower Biohermal Limestone (sample 2). Magn. ×600, 1–9-points of chemical analysis. Cal—low-Mg calcite; Mg-Cal—high-Mg calcite; Pr-Dol—protodolomite. C BSE image of an upper Crinoidea limestone (sample 15) (Stanienda 2004, 2011). Magn. ×1000, 1–7-points of chemical analysis. Cal—low-Mg calcite; Mg-Cal—high-Mg calcite; Pr-Dol—protodolomite. D BSE image of an upper Biohermal limestone (sample 41). Magn. ×1500, 1–8-points of chemical analysis (Stanienda 2006). Cal—low-Mg calcite; Mg-Cal—high-Mg calcite; Pr-Dol—protodolomite
	Fig. 6. A BSE image of an lower Crinoidea limestone (sample 7). Magn. ×2500, 1–6-points of chemical analysis. Cal—low-Mg calcite; Pr-Dol—protodolomite. B BSE image of an upper Biohermal limestone (sample 41). Magn. ×700, 1–10-points of chemical analysis. Cal—low-Mg calcite; Mg-Cal—high-Mg calcite; Pr-Dol—protodolomite; Dol—ordered dolomite. C. BSE image of an Upper Biohermal Limestone (sample 41). Magn. ×900, 1–7-points of chemical analysis. Cal—low-Mg calcite; Mg-Cal—high-Mg calcite; Pr-Dol—protodolomite

References [+] :

Gorzelak, Micro- to nanostructure and geochemistry of extant crinoidal echinoderm skeletons. 2013, Pubmed, Echinobase