ALTERATION AND OXIDATION ALONG AN OLIVINE LAMPROPHYRE DIKE FROM SOUTHERN UTAH, USA: AN ANALOG FOR MARS

Author

Lacey Costello, Southern Illinois University CarbondaleFollow

Date of Award

8-1-2018

Degree Name

Master of Science

Department

Geology

First Advisor

Filiberto, Justin

Abstract

The physical and chemical weathering of iron and magnesium silicates can provide important insights into the environment to which the rock was exposed. The process of iron alteration and oxidation may be particularly prevalent on Mars because Martian basalts usually contain more iron than terrestrial basalts. Specifically, weathering and oxidation may have been prominent during the Noachian, when the atmosphere was likely warmer and wetter and where liquid water could exist to drive alteration and redox reactions. I have investigated a terrestrial analog on the Colorado Plateau for such a process of alteration oxidation of a mafic dike. This work investigates the change from a relatively fresh to an altered mafic intrusion to constrain the effect of alteration on chemistry and mineralogy. There are four main zones of oxidation along the intrusion that can be generally characterized by the difference in color in the field and in hand sample. Calcite, hematite, and kaolinite are the dominant alteration minerals present throughout the intrusion and occur in greater concentration in the more altered samples. These same alteration minerals are also found at Gusev Crater, Mars. This terrestrial analog and thermochemical models show evidence for hot, neutral fluids at intermediate water/rock ratios during the formation of alteration minerals in the terrestrial analog dike and at Gusev Crater.