Science report of the UV-mineral Project of the CREW 136 - Part 2
This report is the second part of the summary of the UV-mineral project of the the CREW 136. After
analysing a stream bed and a dry lake, this report will talk about samples taken in a small canyon
and other samples. The first area is a stream bed in a small canyon at one kilometre north-east of
the MDRS and the second area is in a dry river at 6 kilometres north of the Hab.
Those areas had been prospected in two EVA's. The sampling technique for the canyon consisted in
doing transects every 20 meters, along the river bed. Samples had been taken on each edges and in
the middle of the bed for a total of 18 samples. For the other samples, the EVA had to be aborted
due to bad weather so only three samples were taken from stream beds.
After UV-light and HCl testing, three types of samples were identified. The first type does not
react to HCl nor UV-light. Thus, it does not content evaporitic minerals. For the second type, the
dirt react to the HCl but not to the UV-light. This may be due to the action of erosion and
alteration of the river on the carbonate minerals melting with the clay in the river beds. And the
last type react to the HCl and the UV-light. This could be due to the combination of the erosion and
the creation of evaporitic minerals upstream from the river.
After mapping the samples, the results show that all the samples in the canyon react to the HCl and
the UV-light. The other samples also react but less than the previous. Before the rotation, the
results expected were to find evaporitic minerals created in the rivers and in a dry lake but that
is not the results I have obtained. After prospecting and analysing the samples, I can assume that
the minerals I have found, were not created in the rivers by evaporation. They were transported from
flat areas upstream from the watershed basin in where the water can evaporate. The dry lake was a
little disappointing because I was expected a lot of evaporitic minerals in this area. This state is
due to the high level of clay in the region. This clay is present in all the streams of the region
and create a hard impermeable layer preventing the evaporation of the water. The clue for this is
that under this layer the sediments in the river beds are still wet. Moreover, the climatological
conditions at this time of the year are not good for an intense evaporations indispensable to the
creation of the minerals.
In conclusion, this project has not conduct to the results I was expecting. Indeed, the season for
the project was not the best and the geological conditions of the area are not favourable for the
creation of evaporitic minerals. To summarise, the analysis of evaporitic mineral could not affirm
that a dry river is standing in a place because minerals could come from other places. But, starting
by the fact that the river bring those minerals, it could be possible to conclude the presence of a
dry river. That conclusion could be the aim of an other experiment with an other methodology because
it could be possible to analyse the differences between the inside and outside the bed.
Olivier GOBERT, crew geologist, CREW 136 - February 2014.
Appendix : If requested, I can provide the map I made of the final results. This map content all the
points I have geo-referenced and these points show the intensity of the reaction to the UV light.