[X] My Assistant

[ngunn]

This blockbuster article from Emily seems to justify a new discussion topic:
http://www.planetary.org/blogs/emily-lakda...le-of-gale.html

So many thoughts, so many questions, I don't know where to start. What about Gusev? Were those basalts actually sandstones too?

[Gerald]

The largely basaltic composition of the rocks should imply only short exposure to liquid water.
If physical weathering occurred either in cold highlands on the crater rim or during arid periods, and has then been transported within rather short time via alluvial fans and rivers to the lake, where it has been buried fast enough to prevent water from acting on the rock for too long, this could allow for the preservation of basaltic sediments.
Since there probably hasn't been relevant plate tectonics on Mars, repeated exposure to surface water is less likely than on Earth.

Regarding hematite: Color of the rock and CheMin results show significantly higher hematite at Pahrump than at YB.
The good, and yet unswerded question is: If it's the same type of deposit (lacustrine in a shallow lake), how can the environment change between more and less oxidizing withing a geologically short period?
Maybe the answer can be found by questioning the assumptions, implicite in the question.

[Julius]

The largely basaltic composition of the rocks should imply only short exposure to liquid water.
If physical weathering occurred either in cold highlands on the crater rim or during arid periods, and has then been transported within rather short time via alluvial fans and rivers to the lake, where it has been buried fast enough to prevent water from acting on the rock for too long, this could allow for the preservation of basaltic sediments.
Since there probably hasn't been relevant plate tectonics on Mars, repeated exposure to surface water is less likely than on Earth.

Regarding hematite: Color of the rock and CheMin results show significantly higher hematite at Pahrump than at YB.
The good, and yet unswerded question is: If it's the same type of deposit (lacustrine in a shallow lake), how can the environment change between more and less oxidizing withing a geologically short period?
Maybe the answer can be found by questioning the assumptions, implicite in the question.

Correct if i'm wrong but I believe that pahrump hill rocks are at a higher elevation than yellowknife bay?