Sapphires related to alkali basalts from the Cerová Highlands, Western Carpathians (southern Slovakia): composition and origin
| Authors | |
|---|---|
| Year of publication | 2012 |
| Type | Article in Periodical |
| Magazine / Source | Geologica Carpathica |
| MU Faculty or unit | |
| Citation | |
| Web | http://www.degruyter.com/view/j/geoca.2012.63.issue-1/v10096-012-0005-7/v10096-012-0005-7.xml |
| Doi | http://dx.doi.org/10.2478/v10096-012-0005-7 |
| Field | Analytic chemistry |
| Keywords | Western Carpathians; Slovakia; Hajnáčka; Gortva; CL; LA-ICP-MS; EMPA; oxygen isotopes; placer; alkali basalts; anorthoclasite xenolith; corundum; sapphire |
| Description | Blue, grey-pink and pink sapphires from the Cerová Highlands, Western Carpathians (southern Slovakia) have been studied using CL, LA-ICP-MS, EMPA, and oxygen isotope methods. The sapphire occurs as (1) clastic heavy mineral in the secondary sandy filling of a Pliocene alkali basaltic maar at Hajnáčka, and (2) crystals in a pyroxenebearing syenite/anorthoclasite xenolith of Pleistocene alkali basalt near Gortva. Critical evaluation of compositional diagrams (Fe, Ti, Cr, Ga, Mg contents, Fe/Ti, Cr/Ga, Ga/Mg ratios) suggests a magmatic origin for clastic blue sapphires with lower Cr and Mg, but higher Fe and Ti concentrations in comparison to the grey-pink and pink varietes, as well as similar compositional trends with blue sapphire from the Gortva magmatic xenolith. Moreover, blue sapphires show similar 18O values: 5.1 in the Gortva xenolith, 3.8 and 5.85 in the Hajnáčka placer, closely comparable to mantle to lower crustal magmatic rocks. On the contrary, pink and grey-pink sapphires show higher Cr and Mg, but lower Fe and Ti contents and their composition points to a metamorphic (metasomatic) origin. |
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