45-4 Relative Timing of Sinuous Rilles and Wrinkle Ridges in the Lunar Marius Hills

Session: Surface Processes Across the Solar System (Posters)

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Abstract:

Lunar sinuous rilles are volcanic troughs within the lunar maria (basaltic plains). Although it is widely accepted that sinuous rilles formed by flowing lava, their precise origin (i.e., constructional vs. erosional) is debated. Understanding the formation mechanism of lunar sinuous rilles helps to constrain their eruption duration and style. We conducted geomorphologic mapping and topographic measurements of two sinuous rilles that intersect the same mare-type wrinkle ridge (interpreted to be a thrust fault) in the Marius Hills region. The goal is to determine the relative ages of the sinuous rilles and the wrinkle ridge. If the rilles are younger, the topography requires that the rilles were tube-fed, which suggests a constructional emplacement style.

Geomorphic mapping was conducted with Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images serving as the basemap, with mapping centered at 14.106 °N, 56.541°W. The geomorphic map is used to infer lava emplacement style and cross-cutting relationships between the sinuous rilles and wrinkle ridge. Longitudinal and cross-sectional topographic profiles of the sinuous rilles (obtained using the digital elevation model from SLDEM 2015) are used to help constrain the temporal relationship between the rilles and wrinkle ridge, and to provide data for lava emplacement. Modeling will be conducted to provide constraints to the effusion rates and duration. 

Topographic profiles show localized uplift where the north rille intersects the wrinkle ridge. Rille wall morphology reveals a lack of deformation, such as offset, or rille discontinuity that would be expected if the wrinkle ridge crosscut the rille. Morphology suggests that the sinuous rilles could form after or concurrently with the wrinkle ridge. The elevation of the source depression (vent) is higher than the ridge, and the elevation difference in a pressurized lava tube could provide sufficient potential energy for lava to overtop the ridge. In contrast, topography reveals maximum wrinkle ridge elevation is higher than the source of the south rille. Hence, lava would not be able to flow over the ridge at the south rille if it were purely a gravity-driven flow. This implies the south rille likely predates the wrinkle ridge.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

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