A volumetric, CFM compatible, Geologic Framework Model (GFM)

Andreas Plesch, John H. Shaw, Michael E. Oskin, & Philip J. Maechling

Published August 15, 2019, SCEC Contribution #9706, 2019 SCEC Annual Meeting Poster #319

We present a volumetric version of the SCEC Geologic Framework Model (GFM) which attempts to be compatible with other SCEC Community Models (CXMs) and which can be queried at any 3d location. The model is based on an initial definition of 23 lithotectonic units separated by major faults or contrasts in basement lithology and tectonic affinity. In addition, several lateral interfaces are represented: topography/bathymetry, base of basins, base of seismogenic zone, the Moho, and the lithosphere-asthenosphere boundary (LAB). The base of model is the 100km depth level.

In order to achieve maximum compatibility with the CFM, we first identified all CFM fault representations which define block boundaries. Then individual block boundaries were extracted at the surface level as map coverages. From those, first 3d template surfaces were constructed along the average dips of all CFM faults involved in a given boundary, down to the Moho level. Finally, these template surface were smoothly fit to the detailed CFM fault representations. This procedure was first applied to the three boundaries which were recognized to have more complex, dipping attitudes: the northern and southern boundary of the Western Transverse Ranges, and the southern boundary of the San Gabriel block. Other boundaries are modeled currently with a vertical orientation.

All lateral interfaces were fully modeled from data and extended where necessary to the complete model domain. These are available as separate model components. The base of basins, the base of the seismogenic zone and the Moho were adopted from the CFM and CVM-H, respectively. The LAB was constructed from data provided by Vekic et al. (2011). The resulting LAB surface is smoothed but maintains significant vertical relief (ca. 20km).
From these bounding surfaces, a gridded volume was subdivided into regions. The grid has about 900K 10km x 10km x 1km large cells. It currently has three layers: crust, upper mantle and asthenosphere. The crustal layer contains all 23 lithotectonic units. Each cell is parameterized with a region identification number from 1 to 41 which is mapped to region name. The large number of regions stems from separation of small slivers at acute corner points of blocks. Each cell also has a temperature payload derived from a simple 1D geotherm as an example material property.

SCEC CME developed a prototype query interface which can be used to interrogate the model at any point and depth.

Key Words
structure, lithosphere, crust, mantle, community models

Citation
Plesch, A., Shaw, J. H., Oskin, M. E., & Maechling, P. J. (2019, 08). A volumetric, CFM compatible, Geologic Framework Model (GFM) . Poster Presentation at 2019 SCEC Annual Meeting.

Related Projects & Working Groups
SCEC Community Models (CXM)