CREATING 3D MODELS OF A COMPLEX IGNEOUS INTRUSION TO BETTER UNDERSTAND UPPER-CRUSTAL MAGMATIC SYSTEMS

The 3D visualization of magmatic plumbing systems is essential for understanding magmatic flow, solidification, and eruption processes. This project focuses on creating a 3D model of the Morgantown intrusion located in the Narrow Neck area between the early Mesozoic Newark and Gettysburg rift basins. The intrusion formed during the first phase of magmatism of the Central Atlantic Magmatic Province (CAMP, 201.52 Ma), correlated with the Palisades sill, and is associated with the rifting and breakup of Pangea. CAMP includes some of the largest flood basalts by area in Earth history and influenced end-Triassic mass extinction and biotic recovery. The Morgantown intrusion has a complex shape consisting of interconnected segments, including gently dipping and inclined sheets and steeply dipping dikes that extend from the Paleozoic-Precambrian basement at 6-7 km depth upward to the paleo-surface of the rift basin. The intrusion today covers about 20 km x 15 km, but all units in the rift basin have been tilted, gently folded, and eroded after igneous activity.

To create the 3D visualization, we constructed cross sections using surface, subsurface, and geophysical data and drew contour maps of the elevation of the intrusion surface for the present-day and at the time of emplacement (correcting for later deformation). We then digitized the contour maps using the open-source GIS program, QGIS. The map was georeferenced in the EPSG: 32618 – WGS 84/UTM Zone 18N coordinate system. The model for the reconstructed intrusion surface before deformation was not georeferenced. Structural contours were used to generate a 3D triangular irregular network (TIN). The symbology was enhanced to produce 3D images with false colors representing intrusion surface elevations. We used the plugin Qgis2threejs, which employs the WebGL API, to render the 3D volumetric model. Using colors and symbols, we can plot additional information (e.g., sample and core locations, rock types, and geochemical data) on the 3D models. The maps and 3D reconstructions enable us to identify possible feeder conduits, trace likely magma flow paths, and estimate depths of emplacement below the paleo-surface. Thus, the 3D models provide a framework for interpreting petrologic data and magmatic processes as presented in the companion poster by Finch et al.