Wikipedia:Reference desk/Archives/Science/2021 May 7

= May 7 =

Precambrian stromatolithes and salinity
I haven't been able to find any information on this question from Wikipedia and elsewhere, so here goes nothing: Are there quantitative estimates on how saline (or not) the environments of Archean stromatolites such as these at Strelley Pool. Most sources say things like "hypersaline" but without any elaboration. Jo-Jo Eumerus (talk) 16:01, 7 May 2021 (UTC)
 * Not answering the question, but I thought that the hypersaline conditions prevent animals from eating the bacterial mats. In times before animals that would not have been a problem - eg Cryogenian or before. Graeme Bartlett (talk) 22:09, 7 May 2021 (UTC)
 * Attempting to answer the question - Allwood et al. (2006) describe the depositional environment of the Strelley Pool stromatolites as a broad peritidal carbonate platform, at one point referring to it as "'normal' shallow marine conditions similar to those that have nurtured marine biodiversity throughout geological history". Allwood et al. (2010) go into the detail geochemistry of the sequence stating "REE+Y and other trace element signatures in member 2 indicate that the chert and carbonate were derived from marine water, with variable but small amounts of terrigenous contamination and hydrothermal fluid advection. The close alignment of carbonate and chert trace element chemistry demonstrates that both mineral phases were derived from the same marine fluids, and neither are diagenetic replacement phases derived from, for example, later intrusive hydrothermal fluids. The demise of the stromatolite reef coincided with resumed stronger hydrothermal input in member3 black cherts." Nothing at all there about hypersalinity. Mikenorton (talk) 21:17, 9 May 2021 (UTC)

CDC finally admits the coronavirus is airborne
Yep, it's spread by aerosol and social distancing isn't enough. And wear as good masks as you can find. It only took them 16 months to figure out what I figured out. Now, about those respirators...

Edit: They still say transmission when far apart is uncommon. Imagine Reason (talk) 21:50, 7 May 2021 (UTC)
 * This isn't a general forum. Do you have a question? --OuroborosCobra (talk) 21:57, 7 May 2021 (UTC)