HR: 1330h
AN: P42A-0421    [PDF]
TI: The Big Chill: Did The Lyot Impact Produce a Late Climate Cooling on Mars?
AU: * Brandenburg, J E
EM: jbranden@mail.ucf.edu
AF: Florida Space Institute, MS:FSI, Kennedy Space Center, FL 32899 United States
AB: The Lyot impact basin is a double ringed basin of outer diameter 200km that formed late in Mars history. It was noted by the author[1,2] that the creation of the Lyot impact basin in the Northern Hemisphere of Mars in the early Amazonian Epoch [3] appears to coincide with the 30x reduction of fluvial and peri-glacial resurfacing rates between the Late Hesperian and Early Amazonian Epochs. Recovery of peri-glacial resurfacing rates in the middle Amazonian is followed by fluvial resurfacing rate recovery only in the late Amazonian. This suggests that the impact which formed the Lyot basin may have induced a strong cooling event on the planet. This suggestion of the profound disruption of any extant planetary climate system by the Lyot impactor is reinforced by the study of hydrogen fractionation in water samples from Mars rocks of various ages. Hydrogen fractionation in the water found in the rocks is con-stant from ALH84001 at 4.5 Gyr years old to Nahkala at 1.2.Gyr age, but increases rapidly in the Shergottites at 0.3Gyr age [4]. It has been noted recently that the Lyot basin is surprisingly free of fluvial features[5] relative to its surroundings. [1] Brandenburg J. E. (1995) Earth Moon and Planets, 67, 35-45. [2] Brandenburg J.E. (Absract)2002 Metoritics Soc.Meeting [2] Tanaka K.L. (1986). LPSC 17, JGR Suppl. 91:E139-E158. [4] Watson, L.L. Epstein S., and Stolper, E. M, Meteoritics, 29, 547, (abstract)[5] Head J. W.III (2002) 33rd LPSC .
DE: 1620 Climate dynamics (3309)
DE: 5407 Atmospheres--evolution
DE: 5416 Glaciation
DE: 6225 Mars
SC: Planetary Sciences [P]
MN: 2003 Fall Meeting