ACID SEDIMENTARY ENVIRONMENTS ON MARS?: THE PHYSICAL SEDIMENTOLOGY

Landforms and strata seen on Mars may have formed by acid waters. Traditionally, physical sedimentologists have not considered the possibility that extremely concentrated liquids may have a greater effect on the movement of grains or sediments than pure water. This project compared the effects of dilute water and varying strengths of sulfuric acid on sediment. Using custom built stream tables, water and sulfuric acid were pumped over quartz sand and any similarities or differences in the entrainment, transportation, and deposition between the two liquids were noted. Results show that, though there are similarities between the general behaviors of water and sulfuric acid, there are also key differences. For example, the acid solutions act like fluidized sediment flows in which grains are carried on top of the liquid. The depositional features made by acid and dilute water are similar overall but have small-scale differences. In general, both the water and acid solutions produced such features as alluvial fans and stream channels, but the acid solutions also contained unique depositional and syndepositional features. These include "crater" air bubbles and surface cracks developed due to the density of the acid solution. The features produced by the acid solutions in these experiments resemble features seen in photographs returned from Mars. For example, small craters on Martian alluvial fans look similar to crater air bubbles produced by acid flows in these trials. Also, syndepositional cracks produced by experimental acid runs resemble mysterious cracks in photographed in the Nilo Syrtis region. It has been proposed that a 39% sulfuric acid solution would be a stable liquid on Mars’ surface today (Clark, 1994). That theory coupled with this research and a more detailed understanding of acid systems on Earth could have major implications for Martian research in the future.