Carbon Capture Storage (CCS) relevant Reactive Transport Modelling (RTM) of microfractures in basaltic rock; emulated using Gradient Boosted Decision Trees (GBDT) and subsequently optimised using Bayesian Optimisation (BO) framework. This project's code is hosted on Github at https://github.com/ThomasDodd97/CCS-RTM-GBDT-BO. This upload on Zenodo contains the dataset used to train four XGBoost GBDT surrogate models, whose model files are also uploaded here.