DOI: 10.5061/dryad.kprr4xhdz
title: Code and data used for reproducing calculations of lunar crustal thermal evolution and zircon resetting during a tidal heating event

description: The last giant impact on Earth is thought to have formed the Moon. The
 timing of this event can be determined by dating the different rocks
 assumed to have crystallized from the lunar magma ocean (LMO). This has
 led to a wide range of estimates for the age of the Moon between 4.35 and
 4.51 billion years ago (Gyr), depending on whether ages for lunar
 whole-rock samples or individual zircon grains are used. Here we argue
 that the common occurrence of ~4.35 Gyr ages among lunar rocks and a spike
 in zircon ages at about the same time is indicative of a remelting event
 driven by the Moon’s orbital evolution rather than the original
 crystallization of the LMO. We show that during passage through the
 Laplace Plane Transition the Moon experienced sufficient tidal heating and
 melting to reset the formation ages of most lunar samples, while retaining
 an earlier frozen-in shape and rare, earlier-formed zircons. This new
 paradigm reconciles existing discrepancies in estimates for the
 crystallization time of the LMO, and permits formation of the Moon within
 a few tens of Myr of solar system formation, consistent with dynamical
 models of terrestrial planet formation11.  Remelting of the Moon
 also explains the lower number of lunar impact basins than expected, and
 allows metal from planetesimals accreted to the Moon after its formation
 to be removed to the lunar core, explaining the apparent deficit of such
 materials in the Moon compared to Earth.
description: The dataset is output from three simple fortran programs, which
 are documented in Zenodo
 (https://doi.org/10.5281/zenodo.13968139). The data are
 saved in .csv format  
description: # Code and data used for reproducing calculations of lunar crustal thermal
 evolution and zircon resetting during a tidal heating event
 [https://doi.org/10.5061/dryad.kprr4xhdz](https://doi.org/10.5061/dryad.kprr4xhdz) ## Description of the data and file structure Folder contains the data plotted in Figs 2 and 3 in the main text, and the three Extended Data Figures. These data are saved in .csv format. Columns which are headed "n/a" are dummy columns to aid clarity of viewing the data; entries of "n/a" in a column denote no data. ### Files and variables #### File: Figure3.csv **Description:** Records temperature evolution, zircon closure time and location of intrusions as a function of depth in the crust. Also records the maximum temperature experienced at each depth. The intrusion height is that above the base of the crust, which is 40 km thick. Depth is measured downwards from the surface. Also records a histogram of model zircon closure ages, based on 30 realizations. ##### Variables: Intrusion height(m); Depth (km), zircon closure time (Myr); Depth (km), temperature (C), time (Myr); Depth (km), maximum temperature (C); Model closure time (Myr), histogram frequency. #### File: Figure2.csv **Description:** Records elastic thickness, crustal recycling time and mantle melting time for two different assumed melt fractions (phi) as a function of heat flux. ##### Variables: Heat flux (W/m2), elastic thickness (km), crustal recycling time (Myr), mantle melting time with melt fraction of 10% (Myr), mantle melting time with melt fraction of 3% (Myr) #### File: Extended\_Data\_Fig1.csv **Description:** Records % of crust reset and not intruded as a function of basal heat flux Fb and scale height delta ##### Variables: % of crust reset and not intruded, delta (km), basal heat flux Fb (mW/m2) #### File: Extended\_Data\_Fig2.csv **Description:** Records fraction of zircons with ages 3-6 Myr and fraction with ages that are not reset as a function of scale height delta; Also records  fraction of zircons with ages 3-6 Myr ("in peak") and fraction with ages that are not reset as a function of intrusion thickness and basal heat flux Fb ##### Variables: Scale height delta (km), fraction of zircons with ages 3-6 Myr, fraction of zircons with ages not reset; Intrusion thickness (km), fraction of zircons with ages not reset, fraction of zircons with ages 3-6 Myr ("in peak"), basal heat flux Fb (mW/m2) #### File: Extended\_data\_Fig3.csv **Description:** Records fraction of crust reset but not intruded as a function of heating event duration and scale height delta ##### Variables: Fraction of crust reset but not intruded, duration of heating event (Myr), intrusion scale height (km) #### File: Figure4.csv **Description:** Records Earth dissipation factor QE as a function of Moon formation time for different locations of the evection and LPT resonances, where the LPT resonance distances are given in units of Earth radii (RE). ##### Variables: QE, moon formation time (Myr)