Genesis of autochthonous and allochthonous Apulian karst bauxites (Southern Italy): Climate constraints

Mongelli, Giovanni; Buccione, Roberto; Sinisi, Rosa

doi:10.1016/j.sedgeo.2015.06.005

Cited by 47 publications

(33 citation statements)

References 27 publications

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“…As was previously shown (Figure 8c), the chondrite-normalized REE patterns of SGR samples have paths typical of Apulian autochthonous karst bauxites and of sediments derived from the upper continental crust, with LREE and HREE fractionation indices values (the mean (La/Yb) N value for SGR samples = 9.3) comparable to that of PAAS (Post-Archean Australian Shale, [47]) and UCC ((La/Yb) N = 9.2). According to Mongelli, et al [24], the REE distribution patterns of the Otranto ore slightly differ from those of the other Apulian deposits likely because of its allochthonous nature.…”

Section: Discussionmentioning

confidence: 96%

“…Similarly to the bauxite from Spinazzola, the SGR deposit represents an accumulation of Al-and Fe-rich minerals formed by in situ sedimentary processes [24].…”

Section: Discussionmentioning

confidence: 99%

“…During bauxite formation, climate conditions also control the distribution of chemical elements between textural components [24]. In general, SiO 2 is concentrated mostly in the clayey matrix, whereas Al 2 O 3 , TiO 2 , Fe 2 O 3 , and most trace metals are associated mainly with the ooids [14,16,29,33,34].…”

Section: Discussionmentioning

confidence: 99%

“…In the Gargano district, similarly to the Murge area and the Salento Peninsula, regional intra-Cretaceous unconformities locally occur in the ACP rocks, providing evidence of a wide depositional hiatus and long-lasting subaerial exposure to events that resulted in widespread karstification and bauxite formation. According to Esu and Girotti [23] and Mongelli, et al [24], the autochthonous bauxite deposits of the Murge and Gargano districts were formed during Late Cretaceous (Cenomanian-Turonian) exposure events, while the reworked allochthonous Salento-type bauxite was deposited during the Campanian period.…”

Section: Geological Frameworkmentioning

confidence: 98%

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Mineralogical and Geochemical Features of Cretaceous Bauxite from San Giovanni Rotondo (Apulia, Southern Italy): A Provenance Tool

Sinisi

2018

Minerals

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In this study, the mineralogical and chemical compositions of bauxite from San Giovanni Rotondo (SGR) on the Gargano Promontory (northern Apulia, Italy) are presented and discussed with the aim of assessing the nature of its source material. Bauxite from the SGR, which is known as the “Montecatini mine”, was exploited intensively until the 1970s to recover alumina. As with most of the autochthonous peri-Mediterranean bauxites, the studied deposit is a karst bauxite with a massive, matrix-supported texture and an oolitic structure. Boehmite and hematite are the main mineral phases, and anatase, rutile, and kaolinite are present in lesser amounts along with detrital zircons and monazite grains. Calcite is abundant only in the deposit’s lower portion, triggering a significant dilution effect on trace element concentrations. However, with respect to the average crust and chondrite compositions, strong enrichments of trace metals (up to 10X Upper Continental Crust’s (UCC)) and rare earth elements (REEs, up to 800X chondrite) exist throughout the studied deposit. The distribution of REEs, the (La/Yb)N and Eu/Eu* ratios, and an Eu/Eu* versus Sm/Nd diagram have been used for determining the bauxite’s provenance. These geochemical proxies point to a parental material consisting of a mixture of distant magmatic and siliciclastic components.

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Section: Discussionmentioning

confidence: 96%

“…Similarly to the bauxite from Spinazzola, the SGR deposit represents an accumulation of Al-and Fe-rich minerals formed by in situ sedimentary processes [24].…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Geological Frameworkmentioning

confidence: 98%

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Mineralogical and Geochemical Features of Cretaceous Bauxite from San Giovanni Rotondo (Apulia, Southern Italy): A Provenance Tool

Sinisi

2018

Minerals

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“…The remnants of a bauxitic cover can be recognized on the Cretaceous limestones; it is in some places buried under small patches of two Oligocene lithostratigraphic units -the Galatone Formation and the Lecce Formation -, none cropping out in the studied area. The Salento bauxite derived by the erosion of a weathered pristine deposit formed most likely during the middle Campanian emersion event under dry warm climatic conditions (Mongelli et al 2015).…”

Section: Geological and Geomorphological Settingmentioning

confidence: 99%

Geomorphological Analysis of Karst Landforms at the Masso della Vecchia geosite (Salento Peninsula, Italy)

Sansò

2017

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Prisotnost matične kamnine, ki jo krajevno imenujejo masso della Vecchia, je pomembna geološka zanimivost v okolici vasi Giuggianello (polotok Salento, Apulija, Italija). Zaradi nenavadne naravne reliefne oblike te kamnine in mnogih drugih podobnih kamnin, ki se pojavljajo na tem območju, so nastali številni miti in legende. Naredili smo podrobno geomorfološko analizo masso della Vecchia. študijsko območje je okoli 100 m nad morjem na abrazijskem območju iz spodnjega pleistocena, ki je pravzaprav vrh morfostrukturnega grebena Serra di Poggiardo. Krajevno se iz kamnin miocenske starosti na površju pojavlja Pietra Leccese. Sestavljen je iz slabo strjenih, bioturbacijskih rumenkastih biomikritov, ki se na nižjih ravneh hitro vzpenjajo v masivni grainstone, bogat z mineralom glavkonita. Celotna sekvenca je rahlo nagnjena proti severovzhodu. Geomorfološka analiza je pokazala, da so masso della Vecchia in podobne reliefne oblike, ki se pojavljajo na območju, kraške in da so nastale pod pokrovom prsti. Prepoznali smo vrhove, kanale, zareze, podtalne fasete, polzvonove in druge tipične oblike. Svojevrsten skupek podtalnih kraških oblik je mogoče razložiti z upoštevanjem geološke strukture, podtalnih kraških procesov in geomorfološkega razvoja tega območja v času poznega pleistocena.

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The formation and evolution of Al‐rich protoliths in the southern Ribeira belt, Brazil: Insights from remnants of a Precambrian paleoweathering surface

Santos,

Fedalto,

Bahniuk

et al. 2023

Earth Surf Processes Landf

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Bauxitic clays, clayey bauxites and bauxites are residual products formed from the weathering of aluminosilicate‐rich parent rocks under wet and warm conditions. These deposits show a complex interplay between remobilisation of pre‐existing kaolinitic soils and depositional micro‐environments.In the southern Ribeira belt, Brazil, a paleoweathering surface developed on the continental shelf of the Capiru Group passive margin strata and on its basement/source rocks. This weathering cycle gave rise to a paleosol profile on the continental domain and a karstic paleotopography on the emerged carbonate shelf. The surface and karstic nets were later caped and filled with Al‐rich materials, typical of remobilised soils, bauxitic clays, clayey bauxites and pods of karst‐type bauxites.The age of the disconformity is Pre‐Brazilian/Pan‐African, implying a Neoproterozoic age for the weathering surface. In this study, we investigate the relationship among disconformities, paleosols and karst topography to better understand the stratigraphic control, chemical composition and mineralogy of the Al‐rich materials. We interpret this horizon as the remnants of a (meta‐)paleoweathering surface that can serve as a valuable key bed for stratigraphic correlation and paleogeographic reconstructions.We propose that the triggering process for the genesis of the paleosol profiles, bauxitic material and bauxite pods was a coupled mechanism between favourable climate and uplift along the northern margin of the Curitiba–Angola craton, creating a karstic topography that allowed the down‐plain transport of Al‐rich materials. In a later stage, these deposits were metamorphosed, developing a series of Al silicates in unusual paragenesis, typical of Al‐rich protoliths.The presence of these paragenesis, along with the recognition of the disconformity–paleoweathering surface pair, could be a useful tool to understand the paleoenvironmental and paleogeographic evolution of highly deformed terrains.

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Genesis of autochthonous and allochthonous Apulian karst bauxites (Southern Italy): Climate constraints

Cited by 47 publications

References 27 publications

Mineralogical and Geochemical Features of Cretaceous Bauxite from San Giovanni Rotondo (Apulia, Southern Italy): A Provenance Tool

Mineralogical and Geochemical Features of Cretaceous Bauxite from San Giovanni Rotondo (Apulia, Southern Italy): A Provenance Tool

Geomorphological Analysis of Karst Landforms at the Masso della Vecchia geosite (Salento Peninsula, Italy)

The formation and evolution of Al‐rich protoliths in the southern Ribeira belt, Brazil: Insights from remnants of a Precambrian paleoweathering surface

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