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Abstract

Ringvent is a young shallow saucer-shaped sill intrusion emplaced in the Guaymas Basin in the Gulf of California, Mexico. It is an active hydrothermal cooling magmatic intrusion that allows the evaluation of thermomechanical processes involved in the emplacement of these structures in rift environments, practically in real-time.

This study aims to provide information about the mechanisms involved in sill emplacement by characterizing the physical properties in the contact zone between the sill and the host rock. The physical data used in this project was taken from ten logs and core samples drilled at the Ringvent site by the IODP 385 expedition. The data set includes measurements of density, permeability, p-wave velocities, and magnetic susceptibility that was analyzed, cleaned and plotted to find patterns in the sediment´s behavior around the sill contact area.

As a result of the analysis, we found that some of the factors that contribute to the emplacement of Ringvent are a porosity reduction above the sill, a decrease in the speed of the P-wave velocity, a slight decay in magnetic susceptibility, and the existence of a high-stress resistance layer above the sill.

These results were compared to another site in the Guaymas basin, where an older and deeper sill was emplaced, finding similar patterns. This correlation allows us to contribute to the discussion about the factors involved in sill emplacement and argue about if these observed changes are a result of thermal alteration by the sill, or in contrast, they are what determine the depth and shape of the sill.