Introduction: Clay minerals are the most common alteration products of water-rock-gas interactions on Earth. Because these hydrous alteration minerals are thermodynamically stable over a wide range of P-T-x conditions [1], significant amounts of clay may have also formed in Martian environments where liquid water or water vapor was present. It has been speculated that liquid water or vapor may ...

The Chah-Shur clay deposit is located in150 km southeast of Isfahan. Eocene igneous rocks ‎and Quaternary deposits cover the area. Eocene volcanic rocks include andesite and tuffs ‎which relating to magmatic activities of Urumieh-Dokhtar magmatic belt. Alteration of the ‎vitric and lithic tuff units has produced the clay deposit. Based on the petrographic studies, ‎the main minerals in tuff uni...

Introduction: Numerous studies at the Riotinto mining district have focused on astrobiology, sulfates and extremophilic microbial communities in the highly acidic aqueous environments [1-3]. In contrast, this project investigates past acidic alteration of nearby volcanic rocks. The present study covers a variety of alteration pathways that may influence volcanic protoliths, with the specific ty...

[1] To understand the aqueous history of Mars, it is critical to constrain the alteration mineralogy of the Martian surface. Previously published analyses of thermal infrared (l = 6–25 mm) remote sensing data of Mars suggest that dark regions have 15–20% clay minerals. However, near-infrared (l = 1–3 mm) spectral results generally do not identify widespread clay minerals. Thermal infrared detec...

Introduction: Impact-generated hydrothermal systems may have caused widespread alteration of the crust on early Mars. We previously explored the range of alteration products using several Martian meteorites as crustal proxies: LEW88516 [1-3], Dhofar 378, Chassigny [4], and Nakhla [5]. Overall, the dominating alteration phases are oxides, hydroxides, clay minerals, and other hydrous silicates. O...

Clay minerals from the three principal kinds of zeolitic sediments from the type area for zeolite facies alteration, the Triassic Murihiku Supergroup, Southland, New Zealand, have been studied by TEM. Bentonitic tuff consists largely of smectite and heulandite with minor illite; they occur as replacements of glass shards and are inferred to be direct alteration products of tuff alteration. Both...

The Mars Science Laboratory rover Curiosity found host rocks of basaltic composition and alteration assemblages containing clay minerals at Yellowknife Bay, Gale Crater. On the basis of the observed host rock and alteration minerals, we present results of equilibrium thermochemical modeling of the Sheepbed mudstones of Yellowknife Bay in order to constrain the formation conditions of its second...

Widespread detection of phyllosilicates (clay minerals) in Noachian (>3.5 Ga) terrains on Mars and their paucity in younger terrains have led to the hypothesis that Noachian conditions were more clement than the colder, drier conditions that have since followed. However, recent clay detections in several Hesperian impact craters suggest that fluvial transport and alteration were possible after ...

The subject of hybrids based on layered inorganic compounds such as clays has been studied for a considerable time, but the area is enjoying a resurgence of interest and activity as a result of the exceptional properties which can be realized from such nanocomposites. Common clays are naturally occurring minerals, and are thus subject to natural variability in their constitution. Many clays are...