Depósitos minerais secundários das cavernas Santana, Pérola e Lage Branca, município de Iporanga-São Paulo

Barbieri, Alex José

doi:10.11606/d.44.1993.tde-12082015-143035

Cited by 2 publications

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“…3 and San. 4 a mineral of the apatite group was detected, that correspond to the hydroxylapatite already sampled in the same place and characterised by Barbieri (1993): therefore no further analyses was performed on them. The analyses of the samples from Perolas cave detected several minerals, some of which cannot be considered true "cave minerals".…”

Section: Paolo Forti Ermanno Galli Antonio Rossimentioning

confidence: 99%

“…Until present only a couple of preliminary researches were carried out on the secondary cave minerals of the Perolas-Santana karst system (Barbieri, 1993;Labegalini & Auler, 1997): they report the study of several speleothems, all of which are relatively common for the cave environment. They evidenced the widespread presence of secondary deposits of calcite, aragonite, hydromagnesite, gypsum and limonite.…”

Section: Introductionmentioning

confidence: 99%

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Section: Paolo Forti Ermanno Galli Antonio Rossimentioning

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Cottonballs, a unique subaqeous moonmilk, and abundant subaerial moonmilk in Cataract Cave, Tongass National Forest, Alaska

Curry¹,

Boston²,

Spilde³

et al. 2009

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The Tongass National Forest is known for its world-class karst features and contains the largest concentration of dissolutional caves in Alaska. Within these karst systems exist unusual and possibly unique formations exhibiting possible biological origin or influence. Cataract Cave is an example of such a system. This cave hosts a unique depositional setting in which so-called "cottonballs" line two permanent pools. The cottonballs are a calcitic deposit heavily entwined within a mass of microbial filaments. They are juxtaposed with extensive subaerial calcitic moonmilk wall deposit of a more conventional nature but of an extraordinary thickness and abundance. Both the cottonballs and moonmilk are composed of microcrystalline aggregates (0.20 wt.%) compared to the cottonballs (0.12 wt.%). However, the cottonballs are dominated by monocrystalline needles, whereas the moonmilk is mainly composed of polycrystalline needles. The microbial environments of both displayed similar total microbial cell counts; however, culturable microbial counts varied between the deposits and among the various media. For both, in situ cultures and isolates inoculated in a calcium salt medium produced calcium carbonate mineralization within biofilms. Geochemical variations existed between the deposits. Moonmilk displayed a slightly higher abundance of organic carbon (0.20 wt%) compared to the cottonballs (0.12 wt%). Stable isotopic analysis revealed that the moonmilk (δ13C = -1.6‰) was isotopically heavier compared to the cottonballs (δ13C = -8.1‰) but both are lighter than the host rock (δ13C = +1.1‰). However, the organic carbon δ13C values of both deposits were similar (δ13C = -27.4 and -26.7‰) and isotopically lighter compared to other overlying surface organic carbon sources. Due to the similarities between the deposits, we infer that both the cottonballs and moonmilk are subject to a set of related processes that could collectively be accommodated by the term "moonmilk". Thus, the cottonball pool formation can be characterized as a type of subaqueous moonmilk. The differences observed between the moonmilk and cottonballs may be largely attributable to the changes in the depositional environment, namely in air or water.

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Depósitos minerais secundários das cavernas Santana, Pérola e Lage Branca, município de Iporanga-São Paulo

Cited by 2 publications

References 3 publications

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Cottonballs, a unique subaqeous moonmilk, and abundant subaerial moonmilk in Cataract Cave, Tongass National Forest, Alaska

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