Remote sensing evidence of lava-ground ice interactions associated with the Lost Jim Lava Flow, Seward Peninsula, Alaska

摘要

Thermokarst terrains develop when ice-bearing permafrost melts and causes the overlying surface to subside or collapse. This process occurs widely throughout Arctic regions due to environmental and climatological factors, but can also be induced by localized melting of ground ice by active lava flows. The Lost Jim Lava Flow (LJLF) on the Seward Peninsula of Alaska provides evidence of former lava-ground ice interactions. Associated geomorphic features, on the scale of meters to tens of meters, were identified using satellite orthoimages and stereo-derived digital terrain models. The flow exhibits positive-and mixed-relief features, including tumuli (N= 26) and shatter rings (N= 4), as well as negative-relief features, such as lava tube skylights (N = 100) and irregularly shaped topographic depressions (N = 1188) that are interpreted to include lava-rise pits and lava-induced thermokarst terrain. Along themargins of the flow, there are also clusters of small peripheral pits that may be the products of meltwater or steam escape. On Mars, we observed morphologically similar pits near lava flowmargins in northeastern ElysiumPlanitia, which suggests a common formation mechanism. Investigating the LJLF may therefore help to elucidate processes of lava-ground ice interaction on both Earth and Mars.