Hydrated Mineral Detections in Arabia Terra: Another Evidence for Two Episodes of Deposition at Meridiani

Introduction: Remote sensing and in situ data from recent orbiter and rover missions have provided extensive evidence for the presence of water lain sedimentary rocks on Mars [1]. Imaging spectrometers onboard Mars Express and Mars Reconnaissance Orbiter have also detected hydrated minerals such as ancient phyllosilicates and sulfates on the Martian surface. These minerals appear to have formed in two distinct climatic episodes [2]: 1-The Noachian period (4.2-3.7 Gy), at least transiently warm and wet, resulted in the formation of clays, whereas 2-The intermediate Hesperian (3.7-3.0 Gy) could mark a transition to a dryer and more acidic climate, resulting in the formation of sulfates. In contrast, the younger Amazonian terrains lack hydration features, implying that the surface has been mostly dry for at least 3 Gy [2].