Fig. 4: Overview of the regional geodynamic setting in relation to the metamorphic CO2 contributions to spring and stream waters.
From: Deep CO2 release and the carbon budget of the central Apennines modulated by geodynamics
a, Coloured circles and squares illustrate samples with non-zero yearly average HCO3 from metamorphic carbon, scaled by the concentration21. Where both winter and summer concentrations were available for a sample, the symbol represents an average over the two seasons. White-outlined circles and squares illustrate samples where HCO3 from metamorphic CO2 is zero. The purple line marks the boundary between P-wave velocity (Vp) anomalies at 52 km depth; CAW and SAW on the dashed portion of the line highlight the locations of slab windows in the Central and Southern Apennines, respectively. The orange overlay illustrates the spatial extent of measured CO2 gas emissions, grey circles illustrate the locations and depths of seismicity deeper than 40 km and magnitude 3 or higher, and the black sawtoothed line marks the subduction front. b, Enlarged view of the results within the study area, including the locations of normal faults (black lines). Figure adapted with permission from refs. 8,47,48, Elsevier; ref. 49 under a Creative Commons license CC BY 4.0.
