EPISODICITY OF VOLCANIC AND FLUVIAL PROCESSES ON MARS G. Neukum1, A.T. Basilevsky1,2, and the HRSC Team 1Freie Universitaet Berlin, Malteserstr., , Haus D, Berlin Germany; 2 Vernadsky Institute, Kosygin Str., 19, Moscow, Russia. Contact: The first Moscow Solar System Symposium (1M-S3) Mars system studies Space Research Institute, Moscow, Russia October 11 – 15, 2010

Global geologic map of Mars, Tanaka & Scott, 1986

Shaded relief map of Mars

Areas of study

Mangala Valles

Crater count results for Mangala Valles

Age estimates for different units

Histogram of age estimates for Mangala Valles

The histogram shows peaks of volcanic activity and fluvial/glacial activity The most distinctive peaks are at: ~3.3–3.8 Ga, ~1.8–2 Ga, ~1.2–1.6 Ga, 300 to 800 m.y., ~200 m.y., and ~100 m.y. ago. In some areas, there is indication of an additional peak around ~2.2–2.5 Ga ago. The most prominent peaks are within the latest 1–1.5 Ga and around 3.5 Ga. The period between ~2 and ~3 Ga shows much less activity. All peaks showing up in the fluvially affected areas also roughly show up in the volcanic areas and vice versa. Peaks of some of the cratering ages correlate with the age groups of Martian meteorites. Summary of age histograms for all 12 study areas

Large-scale episodicity of igneous activity on Earth

Large-scale episodicity of mare basalt volcanism on the Moon

Conclusions There has been volcanic and fluvial/glacial geologic activity on the Martian surface at all times from >4 Ga ago until today. This activity was rather continual if to consider all 12 studied regions but with episodic increases of intensity of both volcanic and fluvial/glacial processes at ~3.8–3.3 Ga, 2.0–1.8 Ga, 1.6 to 1.2 Ga, ~800 to 300 m.y., ~200 m.y., and ~100 m.y., and a possible weaker phase around ~2.5–2.2 Ga ago. The episodes we find on the Martian surface in the crater frequency analyses are well coincident with some age groups of the Martian meteorites found in the radiometric age data. Episodes of volcanic activity were probably initiating the fluvial/glacial activity explaining their correlation in time.

Danke schoen! Спасибо за внимание! Thank you for your attention!