QUOTE (centsworth_II @ Aug 31 2012, 01:31 PM)
Interesting how well those tilted back layers match the red lines in this diagram from
a paper by James Wray (interview linked in
post 101) et al.
...phyllosilicate-bearing layers (red lines) exposed in Endeavour rim."
From the text:
...layers within the western rim dip away from the crater interior, as expected if the beds predate Endeavour crater and were back-tilted by the impact."
...The Alpha Particle X-Ray Spectrometer could determine major and minor element chemistry, and the Pancam and Microscopic Imager could document grain sizes, shapes, and possible sedimentary textures (e.g., cross-bedding or laminations too fine to resolve from orbit)..."
This paper suggest that the strata that Oppy is currently investigating predates the formation of Endeavour Crater.
I understand that the majority of the group of craters of which Endeavour is one are thought to date from the late bombardment. I think that Endeavour is a good candidate for a crater formed during the late bombardment because it is so eroded.
It is therefore possible that the strata that Oppy is currently investigating predates the late bombardment. If the clays formed during the deposition of this strata then this clay might also predate the late bombardment and might therefore be more than 4 billion years old. If this was true then this clay might predate the Gale crater clays by several hundreds of millions of years.
However, I understand that the prefered theory for the origin of these clays is that they formed due to weathering in crevaces after the formation of Endeavour crater and so might be contemporaneous with those of Gale crater.