Szczegóły publikacji
Opis bibliograficzny
Agate mineralization in spilitized Permian volcanics from "Borówno" quarry (Lower Silesia, Poland) – microtextural, mineralogical, and geochemical constraints / Tomasz POWOLNY, Magdalena DUMAŃSKA-SŁOWIK, Magdalena Sikorska-Jaworowska, Monika WÓJCIK-BANIA // Ore Geology Reviews ; ISSN 0169-1368. — 2019 — vol. 114 art. no. 103130, s. 1–16. — Bibliogr. s. 14–16, Abstr. — Publikacja dostępna online od: 2019-09-18
Autorzy (4)
- AGHPowolny Tomasz
- AGHDumańska-Słowik Magdalena
- Sikorska-Jaworowska Magdalena
- AGHWójcik-Bania Monika
Słowa kluczowe
Dane bibliometryczne
| ID BaDAP | 125137 |
|---|---|
| Data dodania do BaDAP | 2020-01-16 |
| DOI | 10.1016/j.oregeorev.2019.103130 |
| Rok publikacji | 2019 |
| Typ publikacji | artykuł w czasopiśmie |
| Otwarty dostęp |  |
| Czasopismo/seria | Ore Geology Reviews |
Abstract
Two forms of silica mineralization, i.e.: (1) vein agates and (2) moss agates, were encountered for the first time within spilitized (albite-rich) alkali-basalts from the upper parts of Borówno quarry (Intra-Sudetic Basin). Vein agates consist predominately of length-fast chalcedony evolving into strongly-zoned prismatic quartz with a distinctive blue cathodoluminescence. They exhibit the abundance of microtextures typical of epithermal vein systems (i.e. pseudo-bladed, flamboyant/feathery, jigsaw puzzle/mosaic, and Bambauer quartz), but also comprise numerous solid inclusions such as sulphides (pyrite, marcasite, chalcopyrite, and chalcocite), sulphates (barite), carbonates (calcite, dolomite), carbonaceous material, and hematite. The formation of vein agates was marked by strong variations in physicochemical conditions (pH, silica content) of SiO2-bearing fluids and recrystallization of metastable silica phases (i.e. moganite), coupled with the local replacement of pre-existing sulphates and/or carbonates by silica during boiling-related conditions. Their LREE-enriched rare-earth patterns with positive Eu anomaly invoke the close relationship between host rocks alterations (spilitization) and origin of SiO2-rich fluids. Conversely, moss agates have formed as a result of a spherical growth of siliceous phases within vesicles and contain numerous mineral inclusions of hematite, goethite, anatase, as well as ore-related phases (mottramite and dickite). The examination of their surface micro-morphology showed a strong age-related maturation marked by the development of stacked silica plates (plate-edge-like structure). The botryoidal-shaped, white-coloured, and Al-enriched outermost layer of these agates possibly reflects a rapid deposition of the initial silica gel onto the cavity walls. The HREE-enriched rare-earth patterns of the moss agates, combined with the presence of positive Eu and Ce anomalies, suggest their parental SiO2-rich fluids could be derived from multiple sources (e.g. volcanics mesostasis and/or meteoric waters). The fluids responsible for the formation of agate mineralization within alkali-basalts in Borówno could be derived from syn- or post- alterations of their host rocks. © 2019 Elsevier B.V.
