Re: Report at 2002 LPSC: Mars andesitic rock might support a for mer ocean on Mars.
These authors are experts at mineral analysis from IR spectra. Their geological comprehension is, however, less expert.
Their model is seriously flawed.
Andesites on earth result from Subduction of oceanic crust, not the mere presence of oceans. For instance, the island of Iceland is largely basaltic, as is the entire chain of mid ocean ridges, much of which is submarine.
There is no evidence for subduction on Mars, so the model fails.
As for channels implying oceans, as you well know I have good reason for arguing that this too is fallacious.