Abstract. The southern Alpine regions were affected by several magmatic and volcanic events between the Paleozoic and the Tertiary. This activity undoubtedly had an important effect on the density distribution and structural setting at lithosphere scale. Here the gravity field has been used to create a 3D lithosphere density model on the basis of a high-resolution seismic tomography model. The results of the gravity modeling demonstrate a highly complex density distribution in good agreement with the different geological domains of the Alpine area represented by the European Plate, the Adriatic Plate and the Tyrrhenian basin. The Adriatic-derived terrains (Southalpine and Austroalpine) of the Alps are typically denser (2850 kg m−3), whilst the Alpine zone, composed of terrains of European provenance (Helvetic and Tauern Window), presents lower density values (2750 kg m−3). Inside the Southalpine, south of the Dolomites, a well-known positive gravity anomaly is present, and one of the aims of this work was to investigate the source of this anomaly that has not yet been explained. The modeled density suggests that the anomaly is related to two different sources; the first involves the middle crust below the gravity anomaly and is represented by localized mushroom-shaped bodies interpreted as magmatic intrusions, while a second wider density anomaly affects the lower crust of the southern Alpine realm and could correspond to a mafic and ultramafic magmatic underplating (gabbros and related cumulates) developed during Paleozoic extension.

Abstract. The Southern Alpine regions have been affected by several magmatic and volcanic events between the Paleozoic and the Tertiary. This activity has undoubtedly had an important effect on the density distribution and structural setting at lithosphere scale. Here the gravity field is used to create a 3D lithosphere density model on the base of a high-resolution seismic tomography model. The results of the gravity modelling demonstrate a highly complex density distribution in good agreement with the different geological domains of the Alpine area represented by the European plate, the Adriatic plate and the Tyrrhenian basin. The Adriatic derived terrains (Southalpine and Austrolpine) of the Alps are typically denser (2850 kg m−3), whilst the Alpine zone composed by European terrains provenance (Helvetic and Tauern window) presents lower density values (2750 kg m−3). Inside the Southalpine, south of the Dolomites, a well-known positive gravity anomaly is present and one of the aims of this work is to investigate the source of this anomaly that has not yet been explained. The modelled density suggests that the anomaly is related to two different sources, the first involves the middle-crust below the gravity anomaly and is represented by localized mushroom-shaped bodies interpreted as a magmatic intrusion, while a second wider density anomaly affects the lower crust of the Southern Alpine realm and could correspond to a mafic and ultramafic magmatic underplating (gabbros and related cumulates) developed during Paleozoic extension.

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Alpine lithosphere affected by magmatism based on seismic tomography" provides a very interesting and promising approach to model the density distribution in the Alpine crust. It makes a lot of sense to use existing seismic models as starting point to determine the density structure as they deliver reasonable constraints on Moho depth and principal crustal structures. However, I would like to see a more thorough discussion on the influence of the chosen starting model and of the 1D reference density model on the final result. This doubt is related to the observation C1

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