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We use a 3-D general circulation model to compare the primitive Martian hydrological cycle in " warm and wet " and " cold and icy " scenarios. In the warm and wet scenario, an anomalously high solar flux or intense greenhouse warming artificially added to the climate model are required to maintain warm conditions and an ice-free northern ocean.(More)
MESSENGER observations from Mercury orbit reveal that a large contiguous expanse of smooth plains covers much of Mercury's high northern latitudes and occupies more than 6% of the planet's surface area. These plains are smooth, embay other landforms, are distinct in color, show several flow features, and partially or completely bury impact craters, the(More)
On the basis of geological evidence, it is often stated that the early martian climate was warm enough for liquid water to flow on the surface thanks to the greenhouse effect of a thick atmosphere. We present 3D global climate simulations of the early martian climate performed assuming a faint young Sun and a CO 2 atmosphere with surface pressure between(More)
a r t i c l e i n f o Keywords: Mercury pyroclastic volcanism volatile accretion interior MESSENGER Images obtained by the MESSENGER spacecraft have revealed evidence for pyroclastic volcanism on Mercury. Because of the importance of this inference for understanding the interior volatile inventory of Mercury, we focus on one of the best examples determined(More)
The Medusae Fossae Formation (MFF), covering about 2.1 Â 10 6 km 2 (with an estimated volume of 1.4 Â 10 6 km 3) and straddling the equatorial region of Mars east of Tharsis, has historically been mapped and dated as Amazonian in age. Analysis of the MFF using a range of new observations from recent mission data at multiple resolutions reveals evidence that(More)
We present new observations of pyroclastic deposits on the surface of Mercury from data acquired during the orbital phase of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) mission. The global analysis of pyroclastic deposits brings the total number of such identified features from 40 to 51. Some 90% of pyroclastic deposits are(More)
We present a global survey of candidate pyroclastic deposits on Mercury, derived from images obtained during MESSENGER flybys 1–3 that provided near-global coverage at resolutions between 5 and 0.5 km/pixel. Thirty-five deposits were identified and characterized and are located principally on the floors of craters, along rims of craters, and along the edge(More)
Introduction: Despite decades of research, deciphering the nature of Mars' early climate remains a huge challenge. Although Mars receives only 43% of the solar flux incident on Earth, and the Sun's luminos-ity was likely 20-30% lower 3-4~Ga, there is extensive evidence for aqueous alteration on Mars' late Noachian and early Hesperian terrain. Key features(More)
The Medusae Fossae Formation (MFF) has long been thought to be of Amazonian age, but recent studies propose that a significant part of its emplacement occurred in the Hesperian and that many of the Amazonian ages represent modification (erosional and redepositional) ages. On the basis of the new forma-tional age, we assess the hypothesis that explosive(More)
Introduction: Examination of the products of explosive volcanism can provide information on the composition and volatile inventory of a planet's crust and mantle. Pyroclastic deposits have been recognized in images obtained during MESSENGER's first two flybys of Mercury. In this contribution we use MESSENGER data to revisit a suspected pyroclastic deposit(More)