Terrestrial analogs and thermal models for Martian flood lavas

Abstract

The recent flood lavas on Mars appear to have a characteristic “platy‐ridged” surface morphology different from that inferred for most terrestrial continental flood basalt flows. The closest analog we have found is a portion of the 1783–1784 Laki lava flow in Iceland that has a surface that was broken up and transported on top of moving lava during major surges in the eruption rate. We suggest that a similar process formed the Martian flood lava surfaces and attempt to place constraints on the eruption parameters using thermal modeling. Our conclusions from this modeling are (1) in order to produce flows >1000 km long with flow thicknesses of a few tens of meters, the thermophysical properties of the lava should be similar to fluid basalt, and (2) the average eruption rates were probably of the order of 10 4 m 3/s, with the flood‐like surges having flow rates of the order of 10 5–10 6 m 3/s. We also suggest that these high eruption rates should have formed huge volumes of pyroclastic deposits which may be preserved in the Medusae Fossae Formation, the radar “stealth” region, or even the polar layered terrains.