The Apollo 17 Regolith: Induced Thermoluminescence Evidence for
Formation by a Single Event ~100 Million Years Ago and
Possibly the Presence of Tycho Material.
Abstract
We explored the geological history of the Taurus-Littrow Valley at the
Apollo 17 landing site through the induced thermoluminescence (TL)
properties of regolith samples collected from the foothills of the
Northern and Southern Massifs, near the landing site, and the deep drill
core taken in proximity to the landing site. The samples were recently
made available by NASA through the Apollo Next Generation Sample
Analysis program, in anticipation of the forthcoming Artemis missions.
We found that the two samples from the foothills of the massifs exhibit
induced TL values approximately four times higher than those of the
valley samples. This observation is consistent with their elevated
plagioclase content, indicating their predominantly highland material
composition. Conversely, the valley samples display induced TL values
characteristic of lunar mare material. The samples from the deep drill
core demonstrate uniform induced TL properties, despite originating from
depths of up to 3 meters. Notably, one of the samples from the lower
section of the deep drill core presents anomalous induced TL readings.
This anomaly coincides with elevated levels of low-potassium KREEP,
along with reduced quantities of anorthositic gabbro and orange glass,
and could be due to the traces of phosphate minerals. Alternatively,
this observation raises the possibility that this sample contains Tycho
impact material.
The induced TL data is consistent with the regolith, extending to a
depth of at least 3 meters, having been deposited by a singular event
approximately 100 million years ago. This timing aligns with the
hypothesized formation of the Tycho crater.