mercoledì 9 luglio 2014

Gassendi Hansteen region
Gassendi and Hansteen domes (termed Gassendi 1 and Hansteen 1-2)

by Paolo Lazzarotti

by Mike Wirths

Diameter [km]
Heigth [m]
Gassendi 1
Hansteen 1
Hansteen 2
7.8 ± 0.5
25.0 ± 0.5  
21 x 17 ± 0.5
95 ± 10
1070 ± 100
85 ± 10
    1.4 ± 0.1
    4.9 ± 0.5
    0.52 ± 0.05

Gassendi 1 is another bisected dome, like the domes located near Rima Birt. The dome has a diameter of 7.8 0.5 km, a height of 95 ± 10 m and resulting flank slope of 1.40° ± 0.10°. It  belongs to class C2. As for Birt domes and Menelaus domes the rheologic properties derived for Gas1 indicate rapid effusive processes lasting few months. Mons Hansteen (termed Ha1) is a well known lunar red spot feature in the lunar highlands that has a distinctive arrow-head shape. The height of Mons Hansteen (Ha1) amounts to 1020 m while the slope angle amounts to 4.9° for the steepest part of the examined formation. It is a highland dome formed, like the Gruithuisen domes,  during at least two distinct subsequent eruption phases, a process that may build up steeper edifices. The Gruithuisen highland domes and the dome Ha1 form a separate spectral and morphometric group (class G) due to their steep flank slopes, high volumes, and red spectral signatures, giving rise to the assumption that they have been formed by lava of significantly different composition erupted over a long period of time. Another lunar dome Hansteen 2 is located south of the well known highland dome Hansteen 1 (Mons Hansteen). Its height amounts to 85 ± 10 m, resulting in an average flank slope of 0.53°. The edifice volume corresponds to approximately 18.8 cubic km. The flattened appearance of Ha2 suggests that the rising lavas did not build up a dome through a series of flows. The dome Ha2 is a large and voluminous structure and belongs to class In2 in the classification scheme of possible lunar intrusive domes.