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| Titel |
Small shields smarms on Mars and Venus: Surface manifestation of deep mantle plume |
| VerfasserIn |
L. Xiao, M. Smith, J. Huang, Q. He |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250022143
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| Zusammenfassung |
| In spite of large shield volcanoes on terrestrial planets are most remarkable volcanic edifices
and have been extensively studied, small shields, especially small shields swarms are also
import surface manifestation of deep interior thermal anomalies and indicatives of planetary
thermal history. In this study, we indentified and mapped two shields swarms on Mars based
on MOLA, THEMIS and HRSC data and compared their features with shield fields on Venus.
It is suggested that these terrestrial small shields swarms are surface manifestation of hot
spots or mantle plumes.
There are small shield swarms in Syria Planum and Thaumasia Highland on Mars. More
than seventy small shield volcanoes can be identified in the Syria Planum with an area of
24x104km2. These small shield volcanoes are Hesperian in age and are typically 10-30km in
diameter and 100-250m high. Volcanoes to the north are symmetric and have steeper
slope than those volcanoes to the southeast. Generally, there are few volcanoes
beyond the northwestern Syria plateau. Eleven small volcanoes in the Noachian
Coprates Rise and Thaumasia Highlands have been identified and more than thirty
similar small volcanoes were mapped in Thaumasia Fossae and to the southwest
on the southern cratered highlands. They cover an area about 33x104km2. All of
these Noachian shields have diameters ranging from 50 to 80km, and 1.5-2.0km
high. They are randomly distributed in the heavily crated highlands. These edifices
are heavily cut by radial channels, suggesting the edifices are original shields or
cones.
There are tens thousands of small shields (mostly less than 20 km in diameter) on Venus.
They are randomly distributed on the Venusian surface. We classify those regions with high
concentration of small shields (more than 5 shields within an area of 1000 km2) as small
shield swarms. This density is much higher than that on Mars. They are occurring
primarily in the lowlands. Of total 556 shield swarms, mostly are 100-200km in
diameter. Some are big as 1000 km in diameter. Two major shield swarms are in
Beta-Phoebe-Atla regions and in Akkruva Colles. Small shields in these regions are 2 to 5km
in diameter.
By comparing the morphology and space distribution of small shield swarms on Mars and
Venus, it is suggested that they have some similarity and also many significant differences.
However, it is possibly the early Noachian volcanism of Mars is similar with what we
see on Venus. All these small shield swarms are extrusive volcanism from deep
mantle plume sources. Extensive resurfacing processes have destroyed most small
shields formed in the early Noachian time, and only some big shields are remained. |
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