Mineralogy of recent volcanic plains in the Tharsis region, Mars, and implications for platy-ridged flow composition

Research areas:
Year:
2010
Authors:
Journal:
EARTH AND PLANETARY SCIENCE LETTERS
Volume:
294
Number:
3-4, SI
Pages:
440-450
Month:
JUN 1
ISSN:
0012-821X
Abstract:
Volcanism on Mars occurred until recently, but the mineralogy of recent
lava plains is poorly known because few regions display fresh outcrops
devoid of dust. Using visible and near infrared data of the Mars Express
probe, two new volcanic plains in Noctis Labyrinthus have been
identified, and the existence of a volcanic plain on the floor of Echus
Chasma has been confirmed. Crater retention ages estimated for these
three plains range between 50 and 100 My, corresponding to the Late
Amazonian. These plains represent an excellent opportunity to constrain
the mineralogy of recent volcanic rocks. Results show that basaltic
compositions with plagioclase and high calcium pyroxene are predominant.
The low olivine proportion suggests that the apparent fluidity of these
flat plains is not related to magmas being ultramafic. In addition, a
platy-ridged texture is observed in two of the studied regions. Our
study shows, for the first time, that this texture is associated with
volcanic rocks, and that these rocks are of typical basaltic mineralogy.
Finally, these volcanic plains are located more than 1000 km east of
previously known late Amazonian volcanic centers of the Tharsis region,
an observation to be taken into account when considering models of
recent volcanism on Mars. (C) 2009 Elsevier BM. All rights reserved.