The Moon's formation time recorded in lunar mare basalts
Description
The Moon’s formation time is a key factor for understanding the early evolution of the Earth-Moon system. The lunar magma ocean (LMO) model explains how cumulate mafic materials crystallizing from the LMO form the source of mare basalts (SMB). If the magma ocean was well-stirred, cumulates from it should share an identical initial Pb isotope signature (PbSMB). Because Pb is volatile while U is refractory, PbSMB can provide constraints for the timing of volatile depletion, most likely dating the time of Moon formation via a giant impact into the proto-Earth. The PbSMB is a link between the initial Pb composition of lunar mare basalts and the Moon's early evolution via a two-stage Pb evolution model that provides a simplified but informative framework. Using four mare basalts with well-constrained ages and initial Pb isotopic compositions, we determine the Moon’s formation time at 4516 (-18/+21) Ma and the SMB solidification time at 4377(-27/+57) Ma. Our modelling strategy facilitates the dating of mare basalt fragments lacking Zr-bearing minerals using the initial Pb isotopic compositions constrained by U-poor minerals. This work sheds light on the early evolution of the Moon and taps the potential capacity in chronological studies of mare basalts.
Files
Steps to reproduce
Steps to Set Up the Environment 1. Create a new Conda environment conda create --name simulation_env python=3.8 2. Activate the environment conda activate simulation_env 3. Install required packages a. Install PyTorch (ensure you have GPU support with CUDA if available): pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cu118 b. Install other essential libraries: pip install numpy tqdm 4. Running the Simulation python montecario.py
Institutions
- Institute of Geology and Geophysics Chinese Academy of Sciences