Reconstructing the Tectonic Evolution of the Moon- Student: Nathan Williams

Project: Research project

Description

Conventional wisdom has been that extensional tectonism on the Moon largely ended ~3.6 billion years ago [1] and that contractional deformation ended ~1.2 billion years ago [2]. New NASA Lunar Reconnaissance Orbiter (LRO) high resolution images and topography are forcing a re-assessment of this view. New populations of lobate scarps, wrinkle ridges, and graben are being discovered at scales not previously imaged, and their morphology and stratigraphic relationships imply a more complex and potentially longer-lasting history of deformation of the lunar crust both within mare basins and in the highlands [3]. The reconstruction of the thermal-tectonic-magmatic evolution of the Moon has been flagged by the recent community-wide National Research Council Planetary Science Decadal Survey as among the most important lunar science issues to be studied in the coming decade [4]. With a NASA Earth and Space Science Fellowship and working with my Ph.D. advisor Prof. James Bell and other colleagues at ASU, I plan to reconstruct the tectonic history of the Moon using Mare Frigoris as a type area studying the distribution, controls, and timing of deformation there and extending our results globally. This proposed project directly addresses two fundamental questions that guide NASAs Planetary Science Research Program: 1) What is the inventory of solar system objects and what processes are active in and among them? Several lunar tectonic landforms have previously been identified in Mare Frigoris [5], but many smaller features could not been seen until recently. We will create an updated map of tectonic landforms in Mare Frigoris using high resolution Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) images [6]. Principal stress directions can be inferred from fault orientations and distributions. Maximum compressive stress directions will be mapped and compared to patterns of anticipated mascon, basin-localized, and global stress fields. The remarkably crisp morphologies of many tectonic landforms with few overprinting impact craters in Mare Frigoris and elsewhere on the Moon suggest near-surface faults may have formed recently and could still be active. We will determine the landforms relative ages using superposition and cross-cutting relations, and estimate absolute ages through crater counts. 2) How did the Suns family of planets, satellites, and minor bodies originate and evolve? If some ridges are much younger than their substrate or deform concurrently with scarps due to global contraction, it would significantly increase previous estimates of the change in lunar radius [3, 7-8]. In addition to making age estimates, we will create fault dislocation models for ridge-scarp transitions to determine if their apparent continuity at the surface corresponds to a continuity of faulting at depth. Fault models will be constrained by Lunar Orbiter Laser Altimeter (LOLA) topographic profiles [9] and digital terrain models (DTMs) derived from LROC NAC stereo images [6, 10]. Similar displacements or subsurface geometries on both sides of the transition would provide the strongest evidence yet of a genetic origin between some ridges and scarps.
StatusFinished
Effective start/end date9/1/128/31/15

Funding

  • NASA: Goddard Space Flight Center: $89,365.00

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tectonic evolution
Moon
student
landform
tectonics
crater
lunar crust
stereo image
overprinting
digital terrain model
image resolution
history
altimeter
fault plane
dislocation
basin
research program
graben
stress field
contraction