New Mexico Geological Society Annual Spring Meeting — Abstracts

Recent studies on rifts zones suggest that cinder cones evolve through the growth of a complex magma plumbing systems. Due to their modest geometry, cinder cones have been commonly perceived to form by a single eruption from a single feeder dike. However, feeder dikes are rarely exposed and their remains are easily eroded. Understanding the fundamental system of how magma is redistributed in the Earth’s crust and how cinder cone volcanoes evolve is difficult, as most outcrops are usually restricted to cliffs, ravines and anthropogenic sites. This research will study the complexity of volcanic substructures at the exposed roots of a cinder-spatter cone associated with the middle Miocene Jicin Volcanic field in the northeast Czech Republic. The approach of study is to prepare a detailed map of the Trosky Volcano based on a collection of structural and geophysical techniques to determine how the magma flowed through and from the volcano. Data from field (e.g. geologic mapping and macroscopic observation) and laboratory methods (petrography, paleomagnetism, anisotropy of magnetic susceptibility (AMS), and rock magnetic data) will provide new insights on the history of Trosky Volcano by determining the relative sequence of volcanic events. Field mapping of the area has revealed that there are many distinguishable volcanic features such as eruptive vents, numerous dikes, lava flows, Lava tubes, and volcanic bombs. Each of the volcanic features are unique and they offer indications of its eruptive past. The AMS directional data yields a magnetic fabric from sub-vertical to sub-horizontal with a sense of NE-SW to NW-SE. Most samples have a high susceptibility with an ellipsoid shape that is predominantly prolate. The majority of the samples yield a reverse polarity magnetization with one or two components of magnetization. The dominant magnetic mineral phases are hematite and pyrrhotite. The Trosky Volcano offers an exceptional opportunity to apply focused geophysical techniques to interpret the complex formation process of the internal magmatic plumbing system.