Stochastic joint modelling of hydrothermal alteration halos and associated geological structures applied to mining studies

@inproceedings{marchal:hal-05157102,
 abstract = {Hydrothermal mineral deposits are characterized by sub-concentric envelopes of alteration minerals surrounding the metallic profitable zone. These alteration halos generally have a larger spatial footprint than the targeted mineralization; hence the associated chemical or physical anomalies are often used as exploration pathfinders. Their characterization can also be important per se for mine planning and geometallurgical purposes, as alteration affects the mechanical rock behavior and mineral composition. Therefore, we propose a new approach to jointly model alteration halos and their geological controls. Because the geometry of hydrothermally altered rocks are primarily controlled by geological features such as penetrative structures, fault systems, or unconformities and smaller scale objects such as fracture networks. Our method defines a multicomponent structural skeleton as a support for modeling the boundaries of these halos. Then, a modification phase based on a likelihood term and a Metropolis- Hastings algorithm is introduced to generate skeleton patterns consistent with the spatial data. Skeleton characteristics, such as the number of components, their position and orientation, are modified during this phase. Components are generated using a marked-point process. A pseudo-distance field D(x) to this structural skeleton is calculated at each iteration. As alteration patterns also depend on the petrophysical properties of the host rock, this pseudo-distance field can be adapted to account for heterogeneous rock material. Following an implicit modeling strategy, this pseudo-distance field is used to compute the likelihood term and for extracting alteration fronts in the form of isovalues. The application of the proposed methodology on a 2D outcrop demonstrates the ability of the methodology to jointly infer plausible geometries of alteration halos and of the associated geological structures.},
 address = {Ponta Delgada A{\c c}ores, Portugal},
 author = {Marchal, Paul and Caumon, Guillaume and Collon, Pauline and Ledru, Patrick and Mckee, Kelsey and Mercadier, Julien},
 booktitle = {{International Geostatistics Congress 2024, A Springer book series Quantitative Geology and Geostatistics}},
 editor = {Leonardo Azevedo et al.},
 hal_id = {hal-05157102},
 hal_version = {v1},
 month = {September},
 publisher = {{Springer}},
 series = {Quantitative Geology and Geostatistics},
 title = {{Stochastic joint modelling of hydrothermal alteration halos and associated geological structures applied to mining studies}},
 url = {https://hal.science/hal-05157102},
 volume = {20},
 year = {2024}
}