Science Microthreads

[Catoptric]

Ego and it's tag team of confirmation bias, mixed with cognitive miser behavior (where failure to acknowledge the incongruence with wish-fulfillment, and so people would rather be too lazy to challenge their own thinking) convinces some people that they are still on the "winning team."

A Psychology book:
DENIAL - Self-Dec, False Bel, Origins Human Mind (2013) AJIT VARKI & DANNY BROWER

Though some might argue it postulates a sociological framework based on a faulty premise, of how society evolved from primordial ancestry. On the other hand, perhaps some people really do beat dead horses for pleasure; and they are just in denial about it?

[HighlyIrregular]

https://www.bbc.com/news/articles/cd725pj0g9ro

Unusual rocks discovered on Mars contain the most tantalising evidence yet of potential past life on the Red Planet.

The mudstones, found in a dusty riverbed by Nasa's Perseverance Rover, are dotted with intriguing markings nicknamed leopard spots and poppy seeds...

"We think what we've found is evidence for a set of chemical reactions that took place in the mud that was deposited at the bottom of a lake - and those chemical reactions seem to have taken place between the mud itself and organic matter - and those two ingredients reacted to form new minerals," explained Dr Hurowitz.

In similar conditions on Earth, chemical reactions creating minerals are typically driven by microbes..."We need to see these samples back on Earth," said Prof Gupta.

ChatGPT:

I can’t find any Earth-geology papers that use those exact nicknames (“poppy seeds,” “leopard spots”) for the vivianite/greigite, redox-front features now being discussed for Mars. Those two terms appear to be informal labels coined by the Perseverance team and reporters for the Jezero mudstones, not established terrestrial terminology. On Earth, the same process (early diagenetic iron- and sulfur-cycling producing vivianite and greigite) is well documented—but authors describe the textures as nodules, rims, reaction fronts, mottling, etc., not “poppy seeds” or “leopard spots.”

What Earth literature actually says (same process, different wording)

Vivianite nodules formed during early diagenesis via microbial Fe/S reduction in ferruginous sediments (freshwater & marine): large nodules and growth sequences documented; mechanism tied to microbial iron and sulfate reduction.

Greigite produced during diagenesis (often with mackinawite/pyrite, in rims or nodules; sometimes biogenic via magnetotactic bacteria): reviews and case studies describe rims, nodules, and localized fronts associated with redox changes.

Where “leopard-spot” does appear on Earth—but for a different process

Sedimentary “leopard-spot limestones” are a known term, but refer to dolomitization mottling (irregular/uneven dolomite replacing limestone), not vivianite/greigite redox fronts. Using this as an Earth analog for the Mars features would mix processes.

What the Mars sources call them (and why you’re seeing the terms)

The recent work explicitly introduces “poppy seeds” (Fe-phosphate, vivianite-like) and “leopard spots” (Fe-sulfide cores, greigite-like, with phosphate rims) as informal descriptors for Jezero mudstones; they’re not borrowed from Earth usage.

I haven't found any high-res pictures so I just enlarged the one I found, rotated it, made it a little clearer:

leopard-spots_poppy-seeds_Mars.png (952.03 KiB) Viewed 66 times