Acta Adriatica, Vol. 49 No. 1, 2008.
Izvorni znanstveni članak
Mn-crust todorokite mineralization on SW backshore Cretaceous limestones from the island of Dugi Otok (Central Adriatic, Croatia)
Boško LUGOVIĆ
; Rudarsko-geološko-naftni fakultet Sveučilišta u Zagrebu, Pierottijeva 6, HR-10000 Zagreb, Hrvatska
Branimir ŠEGVIĆ
; Rudarsko-geološko-naftni fakultet Sveučilišta u Zagrebu, Pierottijeva 6, HR-10000 Zagreb, Hrvatska
Tanja ŠEGVIĆ
; Institut za oceanografiju i ribarstvo, P.P. 500, HR-21000 Split, Hrvatska
Sažetak
The southwest shore of the island of Dugi Otok is characterized by the unusual sample occurrence of Mn-hydrated oxide mineralization in the form of botryoidally and globular, fine-laminated concentric aggregates, crusting the Upper Cretaceous backshore limestones. The mineralization consists mainly of Fe impoverished 10-Å tecto-manganate todorokite (enriched in Mg and transition metals) accompanied by accessory MnO·OH. Todorokite chemical composition is typical of a hydrogenous origin in an oxic shallow marine environment. According to our model, Mn has been recurrently leached and mobilized from the Late Pleistocene sea floor sediments located around 50 nautical miles south of Dugi Otok. We propose a link between the Mn-geochemical anomaly of these sediments and the alteration of distinct, spatial close pre-Holocene tephra, dispersed over the entire recent Adriatic area.
Ključne riječi
10-Å manganates; todorokite; hydrogenous origin; pre-Holocene tephra; Dugi Otok island; Adriatic
Hrčak ID:
26477
URI
Datum izdavanja:
1.7.2008.
Posjeta: 1.680 *