Thermal state of the lithosphere in Eastern Paraguay and in Andean Domain (South American Platform)

Abstract

Crustal thermal models that incorporate thermo-barometric data have been developed for estimating depth to 1300 ºC isotherm in two xenoliths provinces: Southeast Paraguay and Andean domain, in South American Platform. Uncertainties in model results has been minimized by imposing reasonable bounds on some of the key model parameters. Considering only the best fit results it is possible to infer average values for geothermal parameters at the surface. This imply heat flow of 86 mWm-2, radiogenic heat production of 1.8 µWm-3. Besides at Moho depth: heat flow of 21 mWm-2, radiogenic heat production of 4.5x10-3 µWm-3, temperature of from Southeast Paraguay. For the Andean Domain, we have the following values for the geothermal parameters: heat flow, 72 mWm-2, radiogenic heat production, 1.0 µWm-3 in surface and heat flow of 33 mWm-2, radiogenic heat production of 2.0x10-3 µWm-3 and temperature of 785ºC in Moho depth. The heat flux estimated for the southeastern Paraguay is higher than that for the Andean domain. This result is in agreement with differences in geological ages between these sites, since the age value for Paraguayan region is approximately 20% lower than the Andean one.

Thermal State of the Lithosphere of Patagonia Via Data of the Xenoliths

“…Ultramafic xenoliths (peridotite-pyroxenites) and eclogitic minerals present in intrusive rocks such as kimberlites, lamproites and alkaline basalts are widely used to infer the temperature and pressure of the upper mantle and lower crust (Kukkonen & Peltonen, 1999;Russell & Kopylova, 1999;Russell et al, 2001;Harder & Russell, 2006;Aulbach et al, 2004;Howarth et al, 2014;Dymshits et al, 2020;Alexandrino et al, 2022). As xenoliths preserve their physical and chemical characteristics while being transported by magmatic processes, we can use this information to estimate the thermal field of the lithosphere using the thermo-barometric equilibrium condition of xenoliths.…”