SPANISH PEAKS AS AN EARTH ANALOGUE FOR PLANETARY INTRUSIONS

In SE Colorado, the Spanish Peaks, White Peaks, and surrounding dikes comprise a well-exposed intrusive complex dating from 20-27 Ma. Emplaced into Cretaceous to Eocene synorogenic sediments of the Laramide Raton Basin, intrusions were exhumed during the Miocene (~14-18 Ma). East and West Spanish Peak are igneous stocks; however, recent studies show radial dikes adjacent to the Peaks are not sourced by the stocks, do not share composition with these central bodies, and are millions of years younger. Erosion and exhumation have revealed the dikes to have complex intersecting relationships with each other, structures, and basin sediments, some of which may limit dike propagation; however, these relationships and their implications for stress regimes during emplacement remain largely uninvestigated. In a compressive stress regime such as that expected in the synclinal Raton Basin, studying intrusions may improve our understanding of how intrusions alter the horizontally compressive stress regimes in the lithospheres of Mars, Mercury, and Venus. Our interpretation of dike swarms on these bodies is largely informed by graben surface expressions (e.g., Tharsis-radial dikes) or dike-emplaced effusive volcanic deposits (e.g., the Northern Smooth Plains of Mercury or impact basin fill on many bodies). With several swarms observed on Mars and >100 radial swarms observed on Venus, a detailed, comprehensive study of one of the few large-scale exposed dike swarms on Earth is warranted. How do dikes and intrusions utilize pre-existing fractures? How does multi-generational magma accent affect basin (or lithospheric) stresses? How is propagation affected by crustal heterogeneities? We conducted over 2 months of fieldwork in the Raton Basin, produced a detailed geological and structural map of the western basin, and generated a database of dikes and their details. Future work can address many standing questions using this comprehensive dataset, helping to inform interpretations of other-planetary intrusive systems.