Wikipedia:Peer review/Banded iron formation/archive1

Banded iron formation

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I've listed this article for peer review because I found it was listed as Start quality but Top importance on a number of projects, and I've just spent a fair amount of time beating the crude scatological metaphor out of it to bring it closer to Good Article quality. At this point I could use some hairy eyeballs scrutinizing it.

Thanks, Kent G. Budge (talk) 19:51, 19 June 2020 (UTC)[reply]

This looks pretty good. My background is chemistry/bio, but geology tends to make my head spin, but so far this has been easy going.

S'okay. I'm actually an astronomer by training, though geology has become an avocation. When I saw that this article was rated top importance in multiple projects, but only start quality (which may have been ungenerous), I thought I'd be bold and see if I couldn't improve the quality.--Kent G. Budge (talk) 15:17, 2 July 2020 (UTC)[reply]

In the "Description" section, you start off by stating the Fe(III)/Fe(II+III) ratio, but then you compare that to a "2:1" ratio for magnetite, which appears to be the Fe(III)/Fe(II) ratio for that compound. Both ratios should be stated in the same way. (If I'm reckoning this right, magnetite comes out at 0.67 and hematite at 1.0?)

It's a good suggestion,and I've edited the article accordingly.--Kent G. Budge (talk) 14:43, 2 July 2020 (UTC)[reply]

In the 3rd para of that section, it's a little jarring to see "Neoproterozoic" introduced when we haven't as yet been introduced to the timescale in which the more typical deposits were laid down.

I've taken a crack at making this a bit less jarring. The full discussion of age distribution is still deferred to Occurences, but I at least give a little context on why "Neoproterozic" is a meaningful qualifier.--Kent G. Budge (talk) 14:58, 2 July 2020 (UTC)[reply]

In "Occurrence", para 5, what "unusual aspects" of Snowball Earth conditions are widely accepted as having promoted BIF formation? Ice interfering with ocean oxygenation?

Yes, that's correct. I've now spelled it out here in brief, leaving the main discussion to Origins. --Kent G. Budge (talk) 15:02, 2 July 2020 (UTC)[reply]

"The Great Oxidation Event" feels interpolated; I had difficulty connecting it with the rest of the article. What is an "MIS-S" signal? Is it accurate to speak of a "pause" in deposition? If I'm interpreting the rest of the article correctly, deep ocean oxygenation, perhaps connected with the Sudbury event, meant that BIFs couldn't be deposited anymore due to lack of sufficient ferrous iron in the water column, except under unusual (Snowball) or local conditions, so I'd be inclined to use a different term. "Pause" suggests transience and later resumption.

Took a crack at making the connection clearer: BIF is an important marker for GOE. Given there's a link to a main article on GOE, this section should only emphasize the connection to BIF. I'm finding it a little problematic how to describe the end of deposition at 1.85 Ga, since there was a small burst of deposition later; it's strictly correct to say that BIG deposition paused, but correct in a way that may indeed give a false impression. Saying deposition ended at 1.85 Ga, but then qualifying that there were a few unusual deposits much later, may be the best compromise. See what you think of the wording now.--Kent G. Budge (talk) 15:16, 2 July 2020 (UTC)[reply]

Hope this provides some food for thought. Choess (talk) 13:27, 2 July 2020 (UTC)[reply]

That ratio business kept bothering me, since in a hypothetical BIF consisting only of iron oxides and chert, 0.67 should be the *lower* bound on the ferric-to-total-iron ratio. From looking at some things like Gole & Klein (1981), the 0.3—0.6 ratios seem accurate, so there's evidently more ferrous iron present than the 1 of 3 in magnetite would account for. Present in silicate minerals, I guess, even in oxide-rich BIFs? No one quite seems to make that explicit. Maybe you could just fudge it by suggesting that the iron oxides were predominantly "magnetite, which contains Fe(II), rather than hematite, which does not." I'll leave it to your discretion to finesse that.

I know what you mean. I almost wonder if the original source meant Fe(II)/(Fe(II)+Fe(III)), but that doesnt' actually fix the problem! I note that the secondary iron minerals mentioned are all ferrous minerals, so, yeah, ferrous silicates and carbonates and not very much hematite. Still. That may be worth digging into the source a bit more, and looking around for other sources that discuss the ratio. --Kent G. Budge (talk) 03:15, 4 July 2020 (UTC)[reply]

You've smoothed out the other issues I brought up very nicely, thanks!
What is that Strathy-Cassells report from 1977? Cite journal doesn't seem like quite the right template for it. There are some fiddly formatting inconsistencies in the references (use of vauthor or not) and I haven't picked over the non-academic references in detail. Other than that, I think it's good shape to go higher up in our review processes. Choess (talk) 00:08, 4 July 2020 (UTC)[reply]

I haven't looked specifically at Strathy-Cassels and it may be one thrown in by an earlier editor that I need to look at harder. But if we're down to cleaning up formatting of refs, we've already made a lot of progress. :) --Kent G. Budge (talk) 03:15, 4 July 2020 (UTC)[reply]

Jens Lallensack

Looks very good overall, and is a highly informative read.
Such organisms would have relied on the reservoir of reduced ferrous iron, Fe(II), in the early ocean to remove the oxygen they produced from their environment – this reads as if there would be a direct action by the organisms, which confused me a bit while reading. Maybe write "which removed" instead of "to remove".

Good point. I've rewritten it to remove any implication that the organisms evolved mechanisms to use Fe(II) to remove oxygen (which is possible but not in the sources) or that there was any "intent" by microorganisms to be protected by Fe(II).--Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

In the case of granular iron formations, the mesobands are attributed to reworking of sediments in shallow water. – This one I do not understand. How is the sediment reworked, and how can this create bands? Can "reworking" maybe linked, or briefly explained?

I've linked to the Winnowing (sedimentology) article as the one that best explains the concept. Unfortunately, this is itself a very stubby article needing more work, so I've also added a very brief explanation. Tell me if this helps.--Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

The microbands within chert layers are most likely varves – Means that the original idea of cyclic microorganism death by oxygen is not valid any more? This could be mentioned to avoid confusion.

I wish I could find a better reference on this. This was Cloud's original theory of mesobanding, but it seems to have fallen into disfavor without anyone actually writing that it is wrong. I'd like to add it as an example of how the original Cloud theory has evolved, but unlike the example I already give (extended rather than sharp peak) which is spelled out in a source, I haven't found a source that spells out that it's wrong. I'm inclined to assume that it's not dead yet as a theory for mesobanding, rather than microbanding. Lemme see what I can do with it, and then let me know if it helps. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

This implies they are also anoxic (devoid of free oxygen) – Nice to have these explanations of important terms, but this one is coming too late, only after the term "anoxic" was already used multiple times.

It's now defined in the first place it's used.--Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

The absence of hydrogen sulfide in anoxic … – this paragraph lacks a source.

First two paragraphs are both Holland. I've spelled it out now with the citation on both paragraphs. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

dissimilatory sulfate reduction – suggest to include the abbreviation DSR here directly, since it is used later on.

Done. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

Some geochemists suggest – I suggest to use past tense always when citing published studies. You do this for the older works, but it is just not possible to draw a line. See also Wikipedia:Manual of Style/Dates and numbers.

Done. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

Banded iron formations most likely formed from sediments with nearly the same chemical composition as the rock we see today. – Confused: So the ferric gels have the same composition? Isn't Fe content much higher than seen in modern sediments?

Ah, yes, I see the potential for confusion. "The rock we see today" means the BIFs as we see them today. I'll spell this out. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

Decarbonization – this process and its significance is not really explained.

I showed the reaction a couple of paragraphs earlier, but I didn't describe it as the decarbonization reaction. Fixed now. Tell me if that clarifies it sufficiently.--Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

and is one of the world's major iron ore provinces. – I suggest to remove this part, as the sentence is already full of superlatives, and the point that it is the largest BIF and so on has already been made.

Fair enough. It's already established that it's yuuuuge. Pulling it out.--Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

The article sometimes uses plural (banded iron formations) but singular in other instances. Is there a reason for this or can this be kept consistent?

The problem is that geologists themselves are sloppy in the usage. There are specific, formal geologic rock units of formation rank that are composed of this stuff; hence there is a class of formal lithostratigraphic units that are banded iron formations. But BIT also gets used as a generic term for a particular kind of sedimentary rock. Unfortunately, I haven't a source to cite that comes out and says "geologists are sloppy in the usage" I can cite on this. Perhaps the safest thing is to always use it in the singular ("banded iron formation") so I'm consistently using it as a type of rock rather than a class of formal lithostratic units, implicitly going with what seems to be the more common usage. Does this sound reasonable?

The alternative is to make it clear that "banded iron formations" refers to the class of formal lithostratigraphic units and "banded iron formation" to the type of rock, but, again, while I think that's right on, it lacks a cite.

I'll wait to hear back what you think before trying to fix this. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

The definition of the name "Banded iron formation" does not become totally clear. "Distinctive units of sedimentary rock" suggests that this is a type of actual Geological Formation (is it)? Or does the term refer to the rock itself?

What I just said. :) It's used in both senses, unfortunately. -- Well, maybe that's the solution; just say that it's used in these two senses somewhere very early in the article (but after the lede). What do you think? --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

The article sometimes gives hypotheses proposed by older studies, and then refutes them with newer studies. However, just the fact that the study is newer is not enough to disregard the older one if we want to keep the neutral point of view. One option is to simply say "x said this" and "y said that" (i.e., using author attribution) without deciding in favour of one study over another. Another option would be to cite more studies to show consensus, or to additionally cite some secondary source (often a good idea) to show consensus that the hypothesis is outdated. This is a subtlety, but in case you want to bring the article to FAC should be paid attention to. --Jens Lallensack (talk) 21:09, 11 July 2020 (UTC)[reply]

I'll see if I can tweak this. It's clear from the literature that there are a lot of unresolved issues. I have Condie as a recent (2015) secondary source, but he seems to lean very heavily on Cloud and the Australians (Trendall etc.) so I'm not sure this proves a consensus. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

Thanks very much for your review. I'm shooting for Good Article for now, but it would be cool to bring this to featured article quality. --Kent G. Budge (talk) 23:03, 11 July 2020 (UTC)[reply]

Thanks for all fixes, looking very good! I see the problem with the definition, it would surely be most helpful for the reader to mention that the term is used for both the rock type and the units, if possible. --Jens Lallensack (talk) 18:31, 12 July 2020 (UTC)[reply]

Thanks for your review; your critiques were good ones. I'm going to take a crack at BIF versus BIFs and simply cite examples of each usage. When I have it in place, please take a look and see it it seems okay. --Kent G. Budge (talk) 18:57, 12 July 2020 (UTC)[reply]