A NEW LOOK - ANALYZING THE 3D ARCHITECTURE OF COLUMBIA RIVER FLOOD BASALT LAVA FLOWS

Large igneous provinces (LIPs) are frequently associated with events of mass extinction and extensive climatic shifts, yet some fundamental questions related to LIPs remain unanswered: How are the large lava flows associated with LIPs that span 100s of km emplaced? What is the eruption style and flow rates? These properties can be best examined from volcanological structures of lava flows and associated features. However, LIP lava flows are challenging to analyze as exposures are constrained to 2D road cuts with limited lateral extent. Furthermore, large flows intersected by canyons are often inaccessible, and satellite images provide low spatial resolution for vertical outcrops. Due to the being the the youngest and most well preserved LIP, the most ideal place to make these examinations is the Columbia River Flood Basalt (CRFB). To date, it has been a challenge to accurately measure the dimensions and spatial relationships of sheet lobes, the building blocks of all LIPs, which comprise a single CRFB lava flow field. In this work, we present a new method to obtain dimensional measurements for sheet lobes in the CRFB by creating a 3D model of a flow field using drone imagery and photogrammetry. Our results help illustrate the 3D architecture of LIP flows, especially the spatial and vertical structure of lobe geometry and lobe-lobe interaction. Lobe geometry directly affects flow structure, thermal history and our ability to correlate flows across 10 - 100s km. Therefore, measurements of flow architecture in a flow field, as developed in our work, is critical for developing and testing quantitative models for lava emplacement associated with LIPs.