DIKE INTRUSION IN A COMPRESSIVE STRESS REGIME: IMPLICATION OF SPANISH PEAKS ANALOGUE FOR DIKE EMPLACEMENT ON VENUS AND BEYOND

The lithospheres of many planetary bodies are understood to be characterized by horizontally compressive stress regimes; however, their associated surfaces are often observed to host dike-fed effusive volcanic deposits and dike swarm-related graben geologic phenomena which should be limited or prohibited by strong horizontal stresses. We investigate the intrusion of stocks and dikes in a locally horizontally compressive stress field using an Earth analogue, the Spanish Peaks, White Peaks, and dikes of the Raton Basin. Our 28 square mile field area spanned the western region of the basin from West Spanish Peak to the frontal thrusts of the Sangre de Cristo Range. We mapped >100 well-exposed Tertiary dikes and recorded their width, composition, jointing habits, and any flow-orientation indicators. All data was collected using the Move Clino smartphone application, with a focus on the dike-related structures. We used this data, and a supplementary geologic map (see complementary GSA abstract), to develop a cross-sectional stress model of the Raton Basin at multiple stages of intrusion. Based on our observations of dike relationships with other dikes, structures, pre-existing tectonic fabrics, and upper crustal heterogeneities, we produce a map of an analogous dike complex on Venus and interpret structures and stresses that may have been necessary to produce that intrusive system. By considering dikes and stocks as part of a system that develops in phases, we investigate how stages of intrusion may systematically alter a local stress field over time, allowing for dike propagation in initially unfavorable stress environments, such as those interpreted for other planetary bodies.