Origin and Distribution of the Intraplate Magmatism of South America

Authors: Bruna Chagas de Melo, Sergei Lebedev, Sally Gibson, Joost de Laat, Nicola Celli, Marcelo Assumpção

Journal: [placeholder]

DOI: [placeholder]

Abstract

The South American platform experienced significant Mesozoic and Cenozoic intraplate volcanism. Using the new high-resolution S-wave velocity tomographic model SACI-24 and an extensive magmatism dataset, we show that intraplate magmatism across South America derives from a single deep mantle plume beneath the continent. Its distribution is controlled by plume-lithosphere interaction and lateral transport along gradients in lithospheric thickness.

Repository Structure

publication/
  data/
    magmatism/           Igneous rock locations and compiled dataset
    hotspots/            Hotspot catalogues and labels
    motion_paths/        Reconstructed hotspot tracks
    flood_basalts/       CAMP and Parana thickness contours
    contours/            LIP outlines, cratons, oceanic features
    dikes/               Mafic dike swarms
    plate_boundaries/    Plate boundary models
    ridges/              Mid-ocean ridge segments
    kimberlites/         Kimberlite and carbonatite data
    seismic_model/       SACI-24 tomographic model (NetCDF)
  code/
    gmt/                 GMT 6 scripts for Figures 1, 3, 5, 7
    python/              Jupyter notebooks for Figures 6 and Supp. Fig. 1
  figures/               Output directory (not tracked)

Dataset Provenance

Compiled Magmatism Dataset

data/magmatism/SA_intraplate_magmatism.csv is the main compiled dataset (429 entries) with columns: longitude, latitude, age_ma, age_error_ma, rock_type, dating_method, reference. It merges data from three sources listed below.

Source Datasets (Table 1 of manuscript)

File	Data type	Reference
data/magmatism/SA_intraplate_magmatism.csv	Compiled igneous rock locations	This study
data/magmatism/igneous_rocks_all.txt	Merged locations (lon, lat, age, ref)	Mizusaki et al. (2002), Ribeiro et al. (2018), Tassinari (1996)
data/hotspots/hotspots_whittaker2015.xy	Present-day hotspot catalogue	Whittaker et al. (2015)
data/motion_paths/motion_path_*_Muller2016_*.xy	Reconstructed hotspot tracks	Muller et al. (2016)
data/motion_paths/motion_path_*_Matthews2016_*.xy	Reconstructed hotspot tracks	Matthews et al. (2016)
data/motion_paths/motion_path_*_Seton2012_*.xy	Reconstructed hotspot tracks	Seton et al. (2012)
data/flood_basalts/camp_demin_*.txt	CAMP sill thickness contours	de Min et al. (2003)
data/flood_basalts/parana_peate_*.txt	Parana basalt thickness contours	Peate et al. (1992)
data/contours/camp_outline.txt	CAMP province contour	Heimdal et al. (2018); de Min et al. (2003)
data/contours/serra_geral_outline.txt	Serra Geral province contour	Zalan (1987)
data/contours/*_kay2007.txt	Patagonian igneous province contours	Kay et al. (2007)
data/dikes/dikes_*_pessano2021.txt	Mafic dike swarms	Pessano et al. (2021)
data/plate_boundaries/bird2003.txt	Digital plate boundary model	Bird (2003)
data/kimberlites/kimberlites_tappe2018.csv	Kimberlite compilation	Tappe et al. (2018)
data/kimberlites/carbonatites_woolley2008.csv	Carbonatite occurrences	Woolley & Kjarsgaard (2008)
data/seismic_model/SACI-24.nc	S-wave velocity tomography	Chagas de Melo et al. (2025)

SACI-24 Tomographic Model

The SACI-24 model (data/seismic_model/SACI-24.nc) is a global S-wave velocity model parameterized on a triangular grid (~120 km lateral knot spacing) with depth nodes at 7, 20, 36, 56, 80, 110, 150, 200, 260, 330, 410, 485, 585, 660, 809, and 1007 km. Velocity perturbations are in percent relative to a 1D reference model. The model is also available from the IRIS Earth Model Collaboration (EMC).

Software Requirements

GMT figures (Figures 1, 3, 5, 7)

• GMT 6.x (modern mode)
• Bash or Zsh shell

Python figures (Figure 6, Supplementary Figure 1)

• Python 3.9+
• Install dependencies: pip install -r code/python/requirements.txt
• Required packages: pygmt, gplately, xarray, numpy, matplotlib, plate-model-manager

Reproducing Figures

All GMT scripts auto-detect the repository root via REPO_ROOT and use relative paths. Run from the code/gmt/ directory:

cd code/gmt/

# Figure 1: Main magmatic provinces map
./fig1_magmatic_provinces.gmt -l fill -m 200 -t 200

# Figure 3: S-wave velocity anomaly maps
./fig3_velocity_maps.gmt

# Figure 5: Hotspot tracks on lithosphere
./fig5_hotspot_tracks.gmt

# Figure 7: Cross-section model comparison
# NOTE: Requires external model data from SubMachine (see below)
./fig7_model_comparison.gmt

For Python notebooks, run from code/python/:

cd code/python/
jupyter notebook fig6_delamination.ipynb
jupyter notebook supp_tristan_tracks.ipynb

External Model Data for Figure 7

Figure 7 compares SACI-24 with whole-mantle models SPiRaL (Simmons et al., 2021), UU-P07 (Amaru, 2007), and SEMum2 (French & Romanowicz, 2015). Cross-section data for these models can be extracted from SubMachine and placed in data/external_models/.

Data Availability Statement

The seismic tomography model SACI-24 is available from the IRIS Earth Model Collaboration (EMC) and is included in this repository. Igneous rock occurrence data were compiled from Mizusaki et al. (2002), Ribeiro et al. (2018), and Tassinari (1996). Hotspot locations follow the compilation of Whittaker et al. (2015). Plate boundaries are from Bird (2003). Mafic dike swarm data are from Pessano et al. (2021). Continental flood basalt thickness data for the Parana province are from Peate et al. (1992) and for CAMP sills from de Min et al. (2003). Plate reconstructions use the models of Muller et al. (2016), Matthews et al. (2016), and Seton et al. (2012), accessed through GPlately. Patagonian igneous province contours are from Kay et al. (2007). Kimberlite data are from Tappe et al. (2018). Carbonatite data are from Woolley & Kjarsgaard (2008). All datasets and figure-generating scripts are archived at [Zenodo DOI] and available at [GitHub URL].

License

• Data: CC-BY-4.0
• Code: MIT License