STILL ACTIVE? Volcanic eruptions have had a varied history in Elysium, as seen in this graph with ages noted in millions of years. Note the large bump of activity about 2.2 billion years ago, and the continuing lower level of activity down toward today. (Image is Figure 8b from the paper.)
Elysium is Mars’ second-largest volcanic province after Tharsis. A new study by Thomas Platz and Gregory Michael (Freie Universität Berlin) published in Earth and Planetary Science Letters (October 30, 2011) counts craters on its volcanos and the main lava flows to sketch a history of volcanic activity in the province.
The researchers find that Elysium shows a few areas that are around 3.9 billion years old, which provides an oldest-known date for activity in the region. “This age is derived from buried craters underlying a shallow flow unit,” say the scientists. Volcanic activity could have occurred before then, but no traces of older surfaces remain.
The flows and crater counts show that Elysium underwent a major peak of volcanic activity centered about 2.2 billion years ago. Thereafter, volcanism dwindled sharply but continued until the recent past; there have been only 12 lava flows in the last 500 million years. The scientists estimate the youngest Elysium lava flows are about 60 million years old, and they note, “Extrapolating the eruption record, it appears likely that this region of Mars is still volcanically active today.”