User talk:Alnagov/Sandbox/Proterozoic-Cambrian boundary

Upper Vendian-Lower Cambrian stratigraphy, the preliminary result: http://vendian.net76.net/tommotian.htm

It is Russian model of Upper Precambrian-Lower Cambrian stratand border is potential subdivision and stratotypes for the global stage subdivisions. Aleksey (Alnagov (talk) 16:03, 7 May 2009 (UTC))

Hi, Aleksey! I waited for Martin to comment, as he knows more about stratigraphy than I do - on a good day I can spell the word, on a great day I can type it correctly. Martin seems still to be thinking this over, so I'll be very rash and make some comments.

I already knew that Cambrian stratigraphy was a mess, and while looking for some background on the page you mentioned I found palaeos.com's page with its links and the amusing diagram that shows how the dating of the Cambrian has changed sinced 1980, and the same site's satirical comments on this messy issue - plus Geologic time scale 1989 (Harland; pp 31-34), which will be a good ref for the difficulty of the issue and the history of attempts to resolve it - having a date stamp in the book's title says enough. I'm also aware that Russian scientists think the "official" timescale is mistaken, and they have to be taken seriously because some many of the rocks and the researchers on the latest Proterozoic and earliest Cambrian are Russian.

I think this is too big and complex a subject for an article on the Burgess fossils. I suggest we copy this to Talk:Cambrian and continue there, with the intention to update Cambrian and then, when that's settled, summarise in other relevant WP articles. The stratigraphy issues may turn out to need so much explanation that an article is required just about them, e.g "Proterozoic-Cambrian boundary", so that Cambrian has room for other sub-topics like paleoenvironments and paleogeography.

Improving WP's coverage of this is not going to be a quick job, because it's a complex and controversial topic. I suggest that in the meantime articles like this one on the Burgess fossils follow the chronology currently in use - not because it's known to be correct (nothing is, in early Cambrian stratigraphy), but because there's no point in putting a lot of work in to dependent articles before the main one is in good shape. Then when the issues are resolved (as much as they are going to be) we can follow the "what links here" links from Cambrian and update the linked articles, including this one on the Burgess fossils.

BTW did you produce the image comparing Russian and western views yourself? A simplified version of that would be worth several thousand words. --Philcha (talk) 09:40, 7 May 2009 (UTC)

It will certainly be useful for discussion, although I agree with Philcha that this is not the best place for it. I think the next stage would be to assemble a range of published sources to back up your image; perhaps an article on 'Stratigraphy of the Cambrian' is in order, and would be a good place to develop a discussion of the points of view? Martin (Smith609 – Talk) 15:01, 7 May 2009 (UTC)

This scheme is not my job. It from these major sources that show modern notion about Vendian-Cambrian subdivisions with its paleontological characteristics and U-Pb date of zircons of Russia:

• A.Yu. Rozanov, V.V. Khomentovsky, Yu.Ya. Shabanov, G.A. Karlova, A.I. Varlamov, V.A. Luchinina, T.V. Pegel’, Yu.E. Demidenko, P.Yu. Parkhaev, I.V. Korovnikov, N.A. Skorlotova (2008). "To the problem of stage subdivision of the Lower Cambrian". Stratigraphy and Geological Correlation. 16 (1): 1–19. doi:10.1007/s11506-008-1001-3.{{cite journal}}: CS1 maint: multiple names: authors list (link)
• M.A. Semikhatov (2008). "The Upper Precambrian." In: "State of level of scrutiny of Precambrian and Phanerozoic stratigraphy of the Russia. The goals of the further studies." Decisions of the Interdepartmental Stratigraphical Committee and its constant Commissions 38. St.-Petersburg: VSEGEI. pp. 15-27.(in Russian)
• A.Yu. Rozanov, I.Ya. Gogin (2008). "The Cambrian System." In: "State of level of scrutiny of Precambrian and Phanerozoic stratigraphy of the Russia. The goals of the further studies." Decisions of the Interdepartmental Stratigraphical Committee and its constant Commissions 38. St.-Petersburg: VSEGEI. pp. 28-35.(in Russian)
• Khomentovsky, V. V. (2008). "The Yudomian of Siberia, Vendian and Ediacaran systems of the International stratigraphic scale". Stratigraphy and Geological Correlation. 16 (6): 581–598.

others resurs I will add a little later Aleksey (Alnagov (talk) 16:03, 7 May 2009 (UTC))

SSF Zone Anabarites in Ediacaran system (>542 Ma)?

Probably, do you have doubts about presence of SSF Zone Anabarites in Ediacaran system (>542 Ma)? The SSF Zone Anabarites find in all volume Nemacit-Daldyn, dates 543.9±0.3 and 553 is not error. This is confirmed by other fossils, new U-Pb dating from SSF zone Anabarites-Protoherzinia of China 541.3±1.3 (http://www.cprm.gov.br/33IGC/1340586.html) but it with a change in spike calibration and use of a newly determined ²³⁵U decay constant (though, I not sure of this), with former standards it ~543. Aleksey (Alnagov (talk) 16:03, 7 May 2009 (UTC))