55, I remember recently grilling you about your disappearing/healed microfractures in the Deer Sky material. Gorgeous stuff.
Okay- first, the scale in the image's field of view is about 40-45mm tall. The laminations are microfine but very distinct. After mining the web for bits to the puzzle I've decided they are all under Bouma D as graded mudstone facies or rhythmic mudstone facies. They were likely produced by flash flooding in a river delta. The specific flow dynamic responsible for this deposition type is called hypopycnal flow, as far as I can infer.
Maybe your Deer Sky was marshy lake that seasonally flooded, bringing in lots of bits likely. I'm kind of obsessed with the seds here because nobody agrees whether the giant inland body of water on the landmass at the time of deposition (Mesoproterozoic) had a solid body of land locked water (lacustrine) or a large body open at both ends to influence from other bodies (marine). My brain tells me I've hit a snag in the sweater and so I've been getting a little more into it, seeing if the humble grindings of my grey matter can suss out a little light.
Your Miocene is much later, but flow dynamics is flow dynamics!
If your interested in a bit of light learning, check out this link. Dude's got a lot of middle of the road type info. Approachable, yet loaded with things to look up and enable the hunger further.
The page is on turbidites, which I find often as ungraded and tumbled rip up clast breccia in either carbonate or a jelly chert which I guess is supposed to be opal-CT. Another hole for me to fall in that's patiently waiting. Anyway, I followed the turbidite trail and learned about Bouma sequence subsequently.
https://www.alexstrekeisen.it/english/sedi/turbidite.phpHere's a shot of a weird display nugget that is a top view of the lamination's orientation. The pink is wavy argillite that is immediately followed by the green medium grained quartzite with foliated illite mica. Flash floods is all I can come to. Maybe it was intertidal but for the clay rich layer to not be impregnated on the "top" by the next layer it would have had to settle out of suspension in the water, be compacted either by dessication or pressure and have a homogenized skin-type reaction to new incoming sediments.
