EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

TETGAR_C: a three-dimensional (3D) provenance plot and calculation tool for detrital garnets

Wolfgang Knierzinger1, Michael Wagreich1, and Eun Young Lee2
Wolfgang Knierzinger et al.
  • 1Department of Geodynamics and Sedimentology, University of Vienna, Vienna, Austria (
  • 2Faculty of Earth and Environmental Science, Chonnam National University, Gwangju, Republic of Korea

We present a new interactive MATLAB-based visualization and calculation tool (TETGAR_C) for assessing the provenance of detrital garnets in a four-component (tetrahedral) plot system (almandine–pyrope–grossular–spessartine). The chemistry of more than 2,600 garnet samples was evaluated and used to create various subfields in the tetrahedron that correspond to calc-silicate rocks, felsic igneous rocks (granites and pegmatites) as well as metasedimentary and metaigneous rocks of various metamorphic grades. These subfields act as reference structures facilitating assignments of garnet chemistries to source lithologies. An integrated function calculates whether a point is located in a subfield or not. Moreover, TETGAR_C determines the distance to the closest subfield. Compared with conventional ternary garnet discrimination diagrams, this provenance tool enables a more accurate assessment of potential source rocks by reducing the overlap of specific subfields and offering quantitative testing of garnet compositions. In particular, a much clearer distinction between garnets from greenschist-facies rocks, amphibolite-facies rocks, blueschist-facies rocks and felsic igneous rocks is achieved. Moreover, TETGAR_C enables a distinction between metaigenous and metasedimentary garnet grains. In general, metaigneous garnet tends to have higher grossular content than metasedimentary garnet formed under similar P–T conditions.

How to cite: Knierzinger, W., Wagreich, M., and Lee, E. Y.: TETGAR_C: a three-dimensional (3D) provenance plot and calculation tool for detrital garnets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7368,, 2020