Shaped by the Double: Investigating Double-Layered Ejecta at Ries and Lonar Craters

Double-layered ejecta (DLE) craters feature distinct ejecta layers, striated surfaces, moat and rampart structures, widely seen as evidence for an ejecta emplacement with fluidized components derived from subsurface volatiles such as water or ice on Earth, Mars, and potentially other bodies like Ceres or Ganymede.

The boundary conditions driving DLE crater formation remain poorly constrained, especially across varying planetary environments. This study examines DLE processes through comparative field analysis of two terrestrial analogs: the 1.2 km-diameter basaltic Lonar crater (India), smaller than typical Martian DLE craters, and the 24 km Ries crater (Germany), which closely matches Martian DLE dimensions and preserves a well-defined ejecta blanket. Both craters provide well-preserved, accessible sites ideal for studying impact dynamics and potential double-impact systems. Ries, paired with the nearby Steinheim crater in a confirmed double impact, is compared to Lonar and the adjacent “Little Lonar” structure, which may represent a secondary impact. Field investigations included drone-based photogrammetry for high-resolution topography, 100 MHz bi-static ground-penetrating radar for subsurface mapping, as well as petrography, rock magnetics, micro-fracture analysis, and identification of shock features such as shatter cones.

Lonar and Ries craters provide rare insight and access on Earth into the mechanisms behind DLE formation. Their study helps refine our understanding of how impact crater formation interacts with the crust in potentially volatile-bearing planets.