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On the formation of thrust fault-related landforms in Mercury’s Northern Smooth Plains: A new mechanical model of the lithosphere
  • Jingchun Xie,
  • Chengli Huang,
  • Mian Zhang
Jingchun Xie
Shanghai Astronomical Observatory (CAS), Shanghai Astronomical Observatory (CAS)
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Chengli Huang
Shanghai Astronomical Observatory (CAS), Shanghai Astronomical Observatory (CAS)

Corresponding Author:[email protected]

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Mian Zhang
Shanghai Astronomical Observatory (CAS), Shanghai Astronomical Observatory (CAS)
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Abstract

There are a large number of tectonic shortening structures distributed across the planet Mercury, which are interpreted as the product of lithospheric deformation mainly attribute to secular cooling of the planetary interior. As the largest single volcanic deposit on Mercury, the northern smooth plains (NSP) is dominated by thrust fault-related landforms, showing particularity in their geomorphic features and requires an assumed weak layer at a shallow depth to account for the thin-rooted deformation in the lithosphere. However, there is a lack of proper mechanical model to account for such layer in the lithosphere beneath the NSP. In this work, we propose a new mechanical model allowing for a mechanically discontinuous lithosphere by introducing the semi-brittle deformation style, with detailed model configurations. Our work simulates a compressive dynamic process to mimic the formation for thrust fault-related landforms in the NSP of 3.8 billion years ago through 2-D numerical simulations. This simulation lasts for 70 million years, resulting in a concentrated and high strain rate region (i.e., weak layer) at shallow depth in the crust and geomorphically consistent surface topography with commonly observed thrust fault-related landforms. Geomorphically steady surface relief suggests that these shortening landforms were formed in a short period of time on geological time scales, and have maintained their basic geomorphic features to present day. The potential influence of the topography at the crust-mantle boundary on the surface relief is also recognized. Additional set of numerical simulations emphasizes that a larger topography facilitates the formation for higher surface relief.