Numerous graben features transect the Tempe Terra plateau in the northeastern Tharsis Rise, making it one of the most heavily structured regions of Tharsis. The origin of the complex fault geometries, generated over three distinct stages of tectonic activity, is still poorly understood. This work distinguishes between locally-sourced and regionally-sourced structures within Tempe Terra, to isolate regional deformation patterns related to the general development of the Tharsis Rise from the effects of local mechanisms. Comparison of structural observations to predicted deformation patterns from different sources of graben formation in the Martian crust demonstrates the important role of magmatic activity at a variety of scales in driving tectonism in Tempe Terra. Noachian (Stage 1) faulting was the result of local magmatic underplating and associated heating and uplift, which formed part of an incipient stage of widespread Tharsis volcanism that predated development of the main Tharsis Rise. Early Hesperian (Stage 2) faults reflect the interaction of regional stresses from growth of the Tharsis Rise with magmatic activity highly localised along the Tharsis Montes Axial Trend – a linear volcanotectonic trendline including the alignment of the Tharsis Montes volcanoes. Early–Late Hesperian (Stage 3) faulting resulted from a series of dyke swarms from a Tharsis-centred plume, which propagated in a regional stress field generated by growth of the Tharsis Rise. As only Stage 2 NNE faults and Stage 3 ENE faults are linked to regional, Tharsis-related stresses, other observed Tempe Terra fault trends can be excluded when evaluating models of Tharsis’s tectonic evolution.
The structurally complex region of Tempe Terra, located in the northeast of the Tharsis Rise on Mars, preserves deformation related to the growth of Tharsis and lies along the trendline formed by the Tharsis Montes volcanoes. We characterise the spatiotemporal tectonic evolution of Tempe Terra based on comprehensive structural mapping. From this mapping, we identified 16 cross-cutting fault sets and placed these in relative time order, based on a hybrid approach using cross-cutting relationships and buffered crater counting. We are thus able to provide a broad framework for understanding the timing of development for the Tharsis Rise and Tharsis Montes axial trend. Our work shows that Tempe Terra has experienced three distinct stages of tectonic activity from the Middle Noachian to the Late Hesperian. Stage 1 involved E--W extension followed by localised NE--SW extension, which produced local zones of N and NW faulting through the centre and west of Tempe Terra in the Noachian. Stage 2 produced intense NE-oriented faulting concentrated along the Tharsis Montes axial trend in the Early Hesperian as a result of a discrete period of NW--SE extension and local volcanism. Stage 3 involved NW--SE extension coinciding with Tharsis volcanic activity, which generated a regional fabric of ENE-trending graben distributed across Tempe Terra from the Early to Late Hesperian. We observe an overall peak in tectonic activity in the Early Hesperian and find that Tharsis-related extensional deformation in the form of NE-oriented radial faulting did not start in Tempe Terra until this time.