I'm investigating the primary dispersion of elements of the epithermal fluid and it is linked a part to the deposition of certain manganese minerals.
Dear Mr. Barrionuevo
You may subdivide the magmatic Mn deposit as follows.
(1) Magmatic manganese deposits
(1) Sedimentary/volcanic-exhalative marine Mn deposits (SEDEX to VOLCEX)
(2) Volcano-sedimentary lacustrine
(3) Epithermal Mn in places with gem quality rodochrosite
(4) Rhodonite skarn
Manganese-bearing volcanic-hosted and volcanosedimentary
deposits (SEDEX to VOLCEX) may either form part of a marine rock series influenced by hot springs mainly in deep water, e.g. East Pacific Rise and Red Sea or they may be attributed to lacustrine
series as at San Francisco, Mexico. They cover a wide range of sedimentary lithologies from Mn carbonate marble to manganiferous chert and occur in magmatic host rocks from manganiferous basalt to rhyolites including their equivalent pyroclastic deposits. These deposits containing rhodochrosite, kutnahorite, Mn calcite, Mn opaline, rhodonite, braunite, jacobsite, hausmannite, cryptomelane, coronadite,todorokite, birnessite and hollandite evolved within shelf sediments, island arcs and along mid-ocean ridges.
Like many submarine volcanic-hosted deposits, the San
Francisco Mn deposit, Mexico, is conformable with the enclosing
sequence, but underlain by sediments and trachytic tuffs in a
lacustrine sequence
Epithermal Mn deposits are known from Pongkor, Indonesia, and from the Sierras Pampeanas, Argentina, not only for their gem-quality rhodochrosite, but also for considerable amounts of Au and Ag
The host rocks of the Sierra Pampeanas Mn deposit are
granodioritic and rhyodacitic rocks, where Mn is found mainly as faultbreccia
cement. The mineral assemblage comprises besides Mn ore
minerals (hollandite, pyrolusite, ramsdellite, romanèchite, cryptomelane)
Fe–Ba–F gangue minerals and abundant clay minerals in the
alteration zone; it is a near-surface epithermal ore deposit. In the Mina
Capillitas, rhodochrosite of gem-quality occurs together with realgar and duranusite
Rhodonite skarn deposits are another ore type where you
might expect crystals of rhodochrosite in jeweler's quality
With kind regards
H.G.Dill
Dear Mr. Dill
Thank you for your comments on understanding Mn as carbonates and silicates in epithermal veins. I will delve into it.
Thank you.
Héctor.
Hi Hector, please have a look by the paper of Márquez-Zavalía & Heinrich (2016): "Fluid evolution in a volcanic-hosted epithermal carbonate–base metal-gold vein system: Alto de la Blenda, Farallón Negro, Argentina" in Mineralium Deposita 51: 873–902. They describe an epithermal rhodochrosite vein deposit at Capillitas near the Bajo de la Alumbrera porphyry Cu-Au deposit in Argentina. Cheers Daniel
Dear Daniel.
Thanks you by the paper. I appreciate this. It will be of great help to me.
Best regards
Héctor.
Dear Mr. Barrionuevo.
I think you can read the papers from Honza Catchpole or Lluis Fontbote about Morocha and San Cristóbal Epithernal Polymetllic Deposits in Domo de Yauli (Peru)
https://pubs.geoscienceworld.org/segweb/economicgeology/article-abstract/110/1/39/128678/Zoned-Base-Metal-Mineralization-in-a-Porphyry?redirectedFrom=PDF
Best Regards.
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