EMPLACEMENT OF THE CERROS DEL RIO INTRUSION BASED ON ANISOTROPY OF MAGNETIC SUSCEPTIBILITY, PALEOMAGNETIC, MAGNETIC SURVEY, PETROLOGICAL, AND PHOTOGRAMMETRY DATA

Feeder dikes bring magma to the surface and often erupt at the surface while non-feeder dikes become arrested in the shallow crust and never reach the surface. The emplacement dynamics between these dikes remain largely unexplored because it is commonly unknown if a dike is a feeder or non-feeder given the variable degrees of erosion. The Cerros Del Rio intrusion was emplaced into Pleistocene to Pliocene Rio Grande rift sediments, basaltic volcanic rocks, and older Oligocene sediments. To test the emplacement model, a total of thirty sampling sites are being analyzed for paleomagnetic, anisotropy of magnetic susceptibility (AMS), and structural studies to characterize and to compare the emplacement of an associated lava flow. A total of fifteen Currie points was conducted to characterize the principal magnetic phases that carry both the remanence and anisotropy. Petrographic data will be used to describe the differences in lava flow composition and any changes in composition of the dike along strike. The field magnetometry data involves the measurement of the Earth's magnetic field intensity spatially around the intrusion. Typically, the total magnetic field and vertical magnetic field gradient is measured. Measurements of the horizontal or vertical component or horizontal gradient of the magnetic field will be made to visualize the dike geometry and map any basement faults or other buried intrusions. Preliminary AMS data reveal an along strike variation in magma flow directions and paleomagnetic data show spatial variations in remanence orientations. Further studies are underway to further document the emplacement geometry of the Cerros Del Rio intrusion.