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Talk:Polymetallic replacement deposit

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I note the article focuses on manto deposits being a source of copper, but there are references online to manto deposits also being a source of silver. Would be great if this page could address this somehow (I am not a geologist myself!) Cheers

In Canada: British Columbia and also Yukon

In Mexico Platosa mine — Preceding unsigned comment added by Nadimkara (talk • contribs) 17:10, 4 August 2011 (UTC)[reply]

The article cites very few to no sources, and from what I have read in the literature, is not representative of Manto deposits. Sillitoe's 2010 Porphyry Copper Systems paper[1] describes carbonate replacement deposits as either chimney or manto, suggesting that the term "Manto" has more to do with the geometry of the orebody rather than a specific genetic deposit style. I suggest that this article be merged with Skarn deposits as a sub-topic. Geomatters (talk) 20:44, 25 September 2013 (UTC)[reply]

Does the Sillitoe paper relate mantos to skarn? The abstract doesn't. I have a hard copy of the paper somewhere ... Manto is an old mining term for a horizontal sheet form orebody many of which are associated with carbonate strata. Skarn is a type of wall rock alteration/metasomatism in limestone adjacent to a "juicy" intrusive. I can visualise such a connection, but would need good references before supporting such a merge. Vsmith (talk) 01:18, 26 September 2013 (UTC)[reply]
The Sillitoe paper refers to them as carbonate replacement deposits distal to porphyry systems, and cites a number of older descriptive papers on individual deposits. I've been digging a bit deeper and chatting with some of the senior geos in my org, and am told that it's an archaic mining term, more representing the morphology of the deposit rather than the genesis. Here's another description from JL Nelson:
Irregularly shaped, conformable to crosscutting bodies, such as massive lenses, pipes and veins, of sphalerite, galena, pyrite and other sulphides and sulphosalts in carbonate hosts; distal to skarns and to small, high-level felsic intrusions.[2]
so I'm not sure if that helps the discussion along at all... Geomatters (talk) 21:57, 26 September 2013 (UTC)[reply]
Did some digging ... looked up the Tintic deposit in the Graton Sales volume. Describes manto-like orebodies like those of Northern Mexico. That tweaked my curiosity and memory ... so did a google search (mexico ore deposit copper manto) which lead to an article re: the Bismark skarn deposit, Mexico which starts out with Deposit types range from porphyry to skarn to chimney and manto styles (the latter three collectively called high- temperature carbonate-replacement deposits [CRDs]) that reflect proximal to distal settings from intrusions...[3] which is in agreement with Sillitoe. A paper referring to this one, discussed the Mochito deposit of Honduras describing it as a distal Zn(-Pb-Ag) skarn in which economic mineralization ... found in mantos and chimneys ...[4] I only have access to the abstract, but there is the connection. The mantos there display skarn gangue mineralogy whereas the Tintic manto assemblage is silica-jasperoid-barite.[5] And the Econ Geo article from 2010 indicates the term/concept is not archaic. Vsmith (talk) 02:52, 27 September 2013 (UTC)[reply]
So should we beef up the Skarn page to discuss the economic geology a bit more, and then add in manto/chimeys as a subsection? At present this article does not describe what we have discussed above. It's a bit tricky, because there is a page for Carbonate hosted lead zinc ore deposits, which should really be a subsection of a currently non-existant CRD page, as you can also have gold and copper CRDs (Carlin type deposits are basically a gold CRD). In any case, there is overlap between the Manto, Skarn, and CRD pages so we should come up with a solution to make this more clear for the casual reader. Geomatters (talk) 21:28, 27 September 2013 (UTC)[reply]

Outdent
The more I look the fuzzier it gets. Manto, as mentioned above, has been used for various orebodies which have an essentially "blanket" or roughly horizontal attitude. "Manto" is applied to roughly horizontal replacement orebodies in carbonate hosts which may be related to skarns per the above. Seems in the "classic" Cananea area the mantos were in part supergene enrichment blankets.[6] And in the Boleo copper-manganese district of Baja Calif manto is used to describe stratabound deposits in clastic sediments on volcanics associated with rifting of Baja from mainland Mexico.[6]

You mention the Carbonate hosted lead zinc ore deposits above and Carlin Au deposits ... but have those been referred to as mantos? Yes they are ~ horizontal and stratabound, but without some ref calling them mantos ...

As I see it, the manto page can be expanded based on various refs for the variety of usages and emphasising the nature of the term as a geometric mining term and not a genetic term. As for the skarn page - it could do with expansion, but not by merging this page there - rather by including more skarn related ore deposits and distal skarns. As for high temp carbonate replacement deposits ... Lindgrens hypothermal. Maybe discuss for inclusion in Ore genesis#Classification of ore deposits. Vsmith (talk) 03:17, 28 September 2013 (UTC)[reply]

The USGS regards "Polymetallic replacement deposits" (in the geometries of mantos, pipes, and veins) to be distinct from "Carbonate hosted lead zinc ore deposits" (better known in the US as Mississippi Valley type Pb-Zn deposits) because of the different mineralogy (no silver or gold in Mississippi Valley type) and the association of Polymetallic replacement deposits with porphyry intrusives, whereas the Miss Valley type have no associated intrusives. Perhaps we should retitle the article to "Polymetallic replacement ore deposit." See: Mineral Deposit Models, USGS Bulletin 1693 (1986) p.99-101. Plazak (talk) 04:18, 28 September 2013 (UTC)[reply]
That sounds like a reasonable solution to me; do you know what steps are necessary to move or rename an article? Geomatters (talk) 19:27, 30 September 2013 (UTC)[reply]

References:

  1. ^ Sillitoe, Richard H. "Porphyry copper systems." Economic Geology 105.1 (2010): 3-41.
  2. ^ Nelson, J.L. (1996): Polymetallic Mantos Ag-Pb-Zn; in Selected British Columbia Mineral Deposit Profiles, Volume 2, D.V. Lefebure and T. Höy, Editors, British Columbia Ministry of Energy, Mines and Petroleum Resources, pages 101-103.
  3. ^ Baker, T., 2004, Composition and evolution of ore fluids in a magmatic-hydrothermal skarn deposit, Geology, v. 32 no. 2 p. 117-120
  4. ^ A. E. Williams-Jones, et al., The Genesis of Distal Zinc Skarns: Evidence from the Mochito Deposit, Honduras, Economic Geology December 2010 vol. 105 no. 8 pp. 1411-1440
  5. ^ Morris, Hal T., The Main Tintic Mining District, Utah, Ch 51 in Ore Deposits of the United States 1933-1967, Vol 2, AIME, 1968, pp. 1043-1073
  6. ^ a b Rafael Eduardo Del Rio Salas, 2011, Metallogenesis for the Boléo and Cananea copper mining districts, PhD dissertation, University of Arizona
Let's wait a few days for more comments. Then, if no one has any better ideas, I or someone else can redirect Manto ore deposit over to Polymetallic replacement deposit per the USGS classification. Also, I note that the USGS lists manganese replacement deposits as a closely allied ore deposit type, so we might include those in the article. Plazak (talk) 13:15, 1 October 2013 (UTC)[reply]

Undid cut-n-paste and moved the article. Vsmith (talk) 01:49, 4 October 2013 (UTC)[reply]

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