The loss of K, REE, Th, and U from a Martian and a terrestrial basalt by acidic leaching

Abstract

Abstract-The mobilization of K, rare earth elements (REE), Th, and U from Martian surface material upon contact with acidic solutions probably occurred extensively on Mars about 4 to 3.5 Ga ago and seems to have occurred locally in more recent times. We have studied the dissolution of these elements by leaching the basaltic shergottite Zagami and the terrestrial basalt BE-N at constant pH values ranging from 5 to 1 in the absence and presence of added salts. Potassium is nearly immobile in Zagami and mobilized readily from BE-N. The REE reside mostly in calcium phosphates and dissolve readily, with those in whitlockite of Zagami reacting slightly better than those in apatite of BE-N. Thorium and U also reside mostly in calcium phosphates. Both dissolve similarly for both basalts and less readily than the REE. The experiments indicate the extent of the mobilization of K, REE, Th, and U, when acidic water leached the surface of Mars. Potassium was released slowly and in a small relative amount. The REE, and particularly the LREE, became mobile readily and were possibly distributed over large areas before immobilization. Thorium and U dissolved more slowly than the REE and were distributed less widely.

Geologic history of Martian regolith breccia Northwest Africa 7034: Evidence for hydrothermal activity and lithologic diversity in the Martian crust

“…The surface and crust of Mars have been the focus of intensive study by orbital spectroscopic observations and in situ surface analysis by landers and rovers [e.g., Bibring et al ., , ; Carr , ; Christensen et al ., ; Ehlmann et al ., ; Grotzinger and Milliken , ; McEwen et al ., ; McLennan et al ., ; McSween et al ., , ; Murchie et al ., ; Poulet et al ., ; Squyres et al ., ; Stolper et al ., ]. Additionally, there have been many detailed analytical investigations of Martian meteorites [e.g., Borg and Draper , ; Brandon et al ., ; Day et al ., ; Dyar et al ., ; Greenwood et al ., ; Herd et al ., ; McCubbin et al ., ; McKay et al ., ; McSween and Treiman , ; Monkawa et 9al ., ; Nyquist et al ., ; Papike et al ., ; Sarbadhikari et al ., ; Shearer et al ., ; Steele et al ., ; Treiman , ; Usui et al ., ; Wadhwa , ] as well as experimental studies that have simulated Martian conditions in the laboratory [e.g., Adcock et al ., ; Collinet et al ., ; Dreibus et al ., ; Filiberto , ; Filiberto and Dasgupta , ; Filiberto et al ., , ; Golden et al ., ; Hurowitz et al ., ; McCanta et al ., ; McCubbin et al ., ; McSween et al ., ; Medard and Grove , ; Monders et al ., ; Musselwhite et al ., ; Nekvasil et al ., ; Papike et al ., ]. These studies have shown that the planet Mars has had a complex geologic history.…”

On the Diversity and Formation Modes of Martian Minerals

“…Leaching, the chemical alteration or chemical weathering of minerals by selective dissolution of elements, has long played a significant role in pedogenesis-the evolution of martian soils (Dreibus et al, 2008;Hurowitz et al, 2006;Retallack, 2014;Thorpe et al, 2021Thorpe et al, , 2022Ye & Michalski, 2021). Of special importance to near-surface processes on Mars, leaching generates fluids rich in elements that can then migrate and participate in authigenic and diagenetic mineralization over a wide range of temperatures (Bullock & Moore, 2004).…”