Naslov
The link between Central Dalmatian karst bauxites (Croatia) and Miocene Climatic Optimum

Autori
Brlek, Mihovil ; Gaynor, Sean ; Mongelli, Giovanni ; Bauluz, Blanca ; Sinisi, Rosa ; Brčić, Vlatko ; Peytcheva, Irena ; Mišur, Ivan ; Tapster, Simon ; Trinajstić, Nina ; Laita, Elisa ; Yuste, Alfonso ; Allard, Thierry ; Mathian, Maximilien ; Šuica, Sanja ; Grizelj, Anita ; Kukoč, Duje ; Schaltegger, Urs

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Book of Abstracts, 3rd European Mineralogical Conference, EMC 2020 / Kierczak, Jakub - Krakov, 2021, 76-76

Skup
3rd European Mineralogical Conference (EMC 2020)

Mjesto i datum
Kraków, Poljska, 29.08.2021. - 02.09.2021

Vrsta sudjelovanja
Poster

Vrsta recenzije
Podatak o recenziji nije dostupan

Ključne riječi
Karst bauxite ; CA-ID-TIMS zircon geochronology ; Maximum depositional age ; Kaolinite and gibbsite ; Miocene Climatic Optimum ; Central Dalmatia

Sažetak
The Miocene Climatic Optimum (MCO) represents a global warm period from approximately 17.0 to 14.7 Ma, which interrupted a period of long-term Cenozoic cooling. Continental paleoclimate records for the MCO vary in quality and global coverage, and due to the unique formation conditions for bauxites, they may serve as an excellent constraint of local climate during this period. In order to elucidate if the MCO promoted the establishment of a wet and warm climate allowing the formation of bauxites in southeastern mid- latitude Europe, we studied a section of previously undated massive karst bauxite (Crveni Klanac, CK) in central Dalmatia, Croatia, hosted in Upper Cretaceous limestones and overlain by Miocene Sinj Basin lacustrine deposits. Integrated mineralogical, morphological, and geochemical analyses indicate the predominant mineral phases of the homogenous bauxite matrix are authigenic, subhedral to euhedral kaolinite, and gibbsite. The in situ mineralization as a consequence of pedogenic processes indicates that the CK bauxites formed autochthonously. In situ U-Pb zircon ages of the lower, middle and upper stratigraphy of the CK bauxite are similar, dominated by Miocene and Oligocene ages, indicating they share similar protolith(s). Subsequent high-precision chemical abrasion-isotope dilution-thermal ionization mass spectrometry analyses indicate a maximum depositional age for bauxite parent material of 16.9576 ± 0.021 Ma. This maximum age of autochthonous bauxitization coincides with the onset of the MCO, and additional stratigraphic geochronological constraints limit the duration of bauxitization to less than approximately 700 ka. In order for insitu bauxitization to have occurred in southeastern parts of the mid-latitude continental European areas, paleoclimatic and paleoenvironmental conditions must have had mean annual temperature greater than 17–22°C and mean annual precipitation of more than 1100–1200 mm (literature data). Therefore, the CK autochtonous bauxites provide an independent climatic constraint, and serve as a novel example of using bauxite deposits for high precision paleoclimate constraints.

Izvorni jezik
Engleski

Znanstvena područja
Geologija

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