[meteorite-list] Precambrian target rock mystery

[jack satkoski]

Met-list,
On the "Geologic Map of the silver city 7.5' Quadrangle west-central 
Montana" are described "Target Rocks" in the Spokane Formation. On the 
red bedding planes of the Spokane formation are areas of Concentric 
bleaching around a central grain.  Central core red, then black, and 
finally gray.  The circles sometimes come in constellations.  According to Dr Martin Bregman " the central nodule is high in strontium, rubidium, etc derived from the Grenville Highlands 
to the east"

I am thinking an ET origin regarding these targets and throwing out idea for comments.  Another geologist suggested the reaction is a type of geo-chromotography but by what?

Phillis Hargrave et al lead author of the above paper with the Montana Bureau 
of Mines and Geology has sent me additional photos to share.  The paper 
should be online.

For now I am going to place my sample on unexposed film to see if there is a pattern.
Photos of first sample with cross section are from rock sample donated to me by Jim Whipple USGS retired.

Thanks to Mike Fiedler for helping me with photos from Google drive.


https://docs.google.com/file/d/0B2BQ-W2L0_vaNmMwTG5UV2NTNXc/edit?usp=sharing
https://docs.google.com/file/d/0B2BQ-W2L0_vaWW9GaWZ3cC02Z1E/edit?usp=sharing
https://docs.google.com/file/d/0B2BQ-W2L0_vab2dTSjF0NUQwTjg/edit?usp=sharing


https://drive.google.com/file/d/0B2BQ-W2L0_vaSDVBak83RUlybmc/edit?usp=sharing
https://drive.google.com/file/d/0B2BQ-W2L0_vaV2VMNHJDYVloMWs/edit?usp=sharing
https://drive.google.com/file/d/0B2BQ-W2L0_vaVC0tWVpvWFZnMW8/edit?usp=sharing

Jack Satkoski