Carbonate has not yet been searched for in these areas by THEMIS.
Here's a report that states qite large carbonate deposits might be missed at the 3 km resolution of TES:

REMOTE SENSING OF EVAPORITE MINERALS IN BADWATER BASIN, DEATH VALLEY, AT
VARYING SPATIAL SCALES AND IN DIFFERENT SPECTRAL REGIONS. J. E. Moersch 1 , J. Farmer 2 , and
A. Baldridge 2 , 1 Department of Geological Sciences, University of Tennessee, 206 G.S. Building, Knoxville, TN
37996, jmoersch@utk.edu; 2 Geology Department, Arizona State University, Tempe, AZ 85287.
Workshop on the Martian Highlands and Mojave Desert Analogs (2001) 4023.pdf
http://www.lpi.usra.edu/meetings/martianhighlands2001/pdf/4023.pdf

Bob Clark