The Determination of the Water Content and Hydrogen Abundance of Two CK- and CV-type Carbonaceous Chondrites Using Thermogravimetric Analysis

Abstract

In the present study, we aim to investigate the thermal changes of two different types of carbonaceous chondrites using thermal analysis technique. For this purpose, Thermogravimetric Analysis (TGA) was used to determine weight loss, water content, and hydrogen abundance of NWA 4964 (CK3) and NWA 5508 (CV3) carbonaceous chondrites as a function of temperature, for the first time. From the TGA results, total weight loss of two samples of NWA 4964 in the temperature range between ambient temperature and 1192 °C is detected to be 1.975 wt% and 2.275 wt%, whereas total weight loss for two NWA 5508 samples is found to be 5.492 wt% and 5.764 wt%, which is higher than that of NWA 4964. In addition, water content of these two CK3 and CV3 carbonaceous chondrites is assigned from TGA data in the temperature range of 200 °C to 800 °C, and it is found that water content of NWA 4964 (1.026 and 0.9952 %) is approximately three times lower than NWA 5508 results (3.030 and 3.117 %). Moreover, TGA analysis indicated that NWA 5508 has higher hydrogen abundances (0.3366 and 0.3463 %) when compared to NWA 4964 (0.114 and 0.1105 %). When all TGA results are taken into account, NWA 5508 (CV3) carbonaceous chondrite is exposed to more thermal alteration as a function of temperature compared to NWA 4964 (CK3) carbonaceous chondrite. As a result, the information about thermal properties of carbonaceous chondrites carried out in the terrestrial laboratories can be very helpful for the present and future space missions.