# LILY Ocean Drilling Database

Marine drill cores no longer need a geologist's rock name as a training target. The usual practice treats shipboard lithology as the ground truth a model should reproduce, yet the six measurements logged on every core (bulk density, magnetic susceptibility, natural gamma radiation and three reflectance channels) are the properties geologists read when they assign that name. A masked variational autoencoder trained on 236,963 observations from 296 boreholes in the LILY database, without labels, separates lithologies as well as a semi-supervised variant (adjusted Rand index 0.237 against 0.247), and raising the label weight a thousand-fold only drops reconstruction from 0.999 to 0.836 while classification barely moves.

Marine drill cores no longer need a geologist's rock name as a training target. The usual practice treats shipboard lithology as the ground truth a model should reproduce, yet the six measurements logged on every core (bulk density, magnetic susceptibility, natural gamma radiation and three reflectance channels) are the properties geologists read when they assign that name. A masked variational autoencoder trained on 236,963 observations from 296 boreholes in the LILY database, without labels, separates lithologies as well as a semi-supervised variant (adjusted Rand index 0.237 against 0.247), and raising the label weight a thousand-fold only drops reconstruction from 0.999 to 0.836 while classification barely moves.