  Deep learning architectures have enriched data analytics in the geosciences,
complementing traditional approaches to geological problems. Although deep
learning applications in geosciences show encouraging signs, the actual
potential remains untapped. This is primarily because geological datasets,
particularly petrography, are limited, time-consuming, and expensive to obtain,
requiring in-depth knowledge to provide a high-quality labeled dataset. We
approached these issues by developing a novel deep learning framework based on
generative adversarial networks (GANs) to create the first realistic synthetic
petrographic dataset. The StyleGAN2 architecture is selected to allow robust
replication of statistical and esthetical characteristics, and improving the
internal variance of petrographic data. The training dataset consists of 10070
images of rock thin sections both in plane- and cross-polarized light. The
algorithm trained for 264 GPU hours and reached a state-of-the-art Fr\'echet
Inception Distance (FID) score of 12.49 for petrographic images. We further
observed the FID values vary with lithology type and image resolution. Our
survey established that subject matter experts found the generated images were
indistinguishable from real images. This study highlights that GANs are a
powerful method for generating realistic synthetic data, experimenting with the
latent space, and as a future tool for self-labelling, reducing the effort of
creating geological datasets.
