Kiel 2004 – wissenschaftliches Programm

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EP: Extraterrestrische Physik

EP 8: Poster-1

EP 8.10: Poster

Montag, 8. März 2004, 17:45–19:30, Foyer

STRATIGRAPHY AND AGES OF VOLCANIC DOMES IN THE HANSTEEN AND HELMET REGIONS ON THE MOON — •Roland Wagner¹, James W. Head III², Ursula Wolf¹, and Gerhard Neukum³ — ¹Institute of Planetary Research, German Aerospace Center (DLR), Rutherfordstrasse 2, D-12489 Berlin, Germany — ²Dept. of Geol. Sciences, Brown Univ., Providence, RI, USA — ³Institut für Geowissenschaften, Freie Universität Berlin, Malteserstrasse 74, D-12249 Berlin, Germany

The dominating volcanic process on the moon was the emplacement of basaltic lava which formed the dark mare regions on the nearside. A spatially less abundant volcanic process is associated with volcanic domes formed by lava materials of higher silica content and much higher viscosity, which are characterized by a high albedo, a strong absorption in the UV (red spots), and also by a wide range of morphologies. (1) Photogeologic mapping, (2) measuring crater frequencies on mapped units, and (3) the application of an impact chronology model was used to put constraints on the crustal evolution during lunar geologic history. Two areas displaying volcanic domes were selected for this study: regions Hansteen ( ≈ 11.5^o S, 50^o W), and Helmet (( ≈ 16^o S, 30^o W). Photogeologic mapping and measurements of crater frequencies were carried out on Lunar Orbiter high-resolution frames. Results show that high-silica, high-viscosity volcanism was active during a period of about 3.8-3.9 Gyr and was comparably short-lived while low-silica, low-viscosity mare basalts were emplaced during a much more extended period of time (several 100 Myr).