Controls of the lithospheric thermal field of an ocean-continent subduction zone: the southern Central Andes

Abstract

In an ocean-continent subduction zone, the assessment of the lithospheric thermal state is essential to determine the controls of the deformation within the upper plate and the dip angle of the subducting lithosphere. In this study, we evaluate the degree of influence of both the configuration of the upper plate and variations of the subduction angle on the lithospheric thermal field of the southern Central Andes (29°–39°S). Here, the subduction angle increases from subhorizontal (5°) north of 33°S, to steep (~30°) in the south. We derived the 3D temperature and heat flow distribution of the lithosphere in the southern Central Andes considering conversion of S wave tomography to temperatures together with steady-state conductive modeling. We found that the orogen is overall warmer than the forearc and the foreland, and that the lithosphere of the northern part of the foreland appears colder than its southern counterpart. Sedimentary blanketing and the thickness of the radiogenic crust exert the main control on the shallow thermal field (< 50 km depth). Specific conditions are present where the oceanic slab is relatively shallow (< 85 km depth) and the radiogenic crust is thin, This configuration results in relatively colder temperatures compared to regions where the radiogenic crust is thick and the slab is steep. At depths >50 km, the temperatures of the overriding plate are mainly controlled by the mantle heat input and the subduction angle. The thermal field of the upper plate likely preserves the flat subduction angle and influences the spatial distribution of shortening.

Authors 8

1. Constanza Rodríguez Piceda

   GFZ Helmholtz Centre for Geosciences · University of Potsdam

   Affiliation as printed

   HelmholtzZentrum GFZ -German Research Centre for Geosciences, Potsdam, Germany

   University of Potsdam, Institute of Geosciences, Potsdam, Germany

2. Magdalena Scheck‐Wenderoth Aachen

   RWTH Aachen University · GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   HelmholtzZentrum GFZ -German Research Centre for Geosciences, Potsdam, Germany

   RWTH Aachen University, Aachen, Germany

3. Bott Judith

   GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   HelmholtzZentrum GFZ -German Research Centre for Geosciences, Potsdam, Germany

4. Marı́a Laura Gómez Dacal
5. Mauro Cacace

   GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   HelmholtzZentrum GFZ -German Research Centre for Geosciences, Potsdam, Germany

6. Michaël Pons

   GFZ Helmholtz Centre for Geosciences · University of Potsdam

   Affiliation as printed

   HelmholtzZentrum GFZ -German Research Centre for Geosciences, Potsdam, Germany

   University of Potsdam, Institute of Geosciences, Potsdam, Germany

7. Claudia Prezzi

   Universidad de Buenos Aires · Consejo Nacional de Investigaciones Científicas y Técnicas · GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   HelmholtzZentrum GFZ -German Research Centre for Geosciences, Potsdam, Germany

   IGEBA-(UBA-CONICET) Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina

8. Manfred R. Strecker

   GFZ Helmholtz Centre for Geosciences

   Affiliation as printed

   HelmholtzZentrum GFZ -German Research Centre for Geosciences, Potsdam, Germany