228-ScienceReport

Science Report

02/28/2014

Olivier Gobert

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.