Determining Relative Ages of Structural Features Around Irnini Mons, Venus - A Comparison of Type Locations to Resolve the Timing of Cross-cutting Features

English Abstract:

Irnini Mons, a volcano in central Eistla Regio at 14ºN, 16ºE, is roughly centered on the V-20 quadrangle of Venus. While Eistla Regio as a whole is known to have the highest degree of polyphase deformation on Venus, the area immediately around Irnini Mons is particularly complex, even at the 1:5,000,000 scale of the quadrangle map. The arrangement of cross-cutting tectonic structures indicates a detailed and multipart stress history, which suggests Irnini Mons is an ideal location to identify distinct patterns of changes in stress orientation over time, as well as to ascertain the deformation associated with the volcano relative to the deformation of the local regional plains. A thorough investigation of the distribution and orientation of the numerous structures around Irnini Mons at the highest possible resolution (75 m/pixel) is likely to reveal the relative timing of the structures and thus shed light on the deformation history of this region of Venus. However, the complicated nature of these structures and their relationship to each other makes it difficult to resolve relative ages holistically across the map. For this reason, we attempt to determine the relative ages of structures within four distinct type locations within the region, fitting the outcomes of these analysis into an analysis of relative timing of structures within the greater mapped area. For this study, we build upon previous mapping and the determination of structural ages for four type locations spanning across the northwest and southeast regions of the map in an attempt to resolve the timing of features within an entire swath of the map stretching from the northwest corner to the southeast corner. Previous mapping in this area provided examples of how this high-resolution structural mapping may differ from the V-20 map and we will build upon this work by focusing on the high-resolution structural mapping of the four type locations described above.