A heat production model for stable continental lithosphere by the inversion of the surface heat flows

TL;DR

This paper introduces a novel method to infer the heat production distribution within the stable continental lithosphere by inverting surface heat flow data, using a linearized approach and a Parker-Oldenburg type formula, demonstrated on a Chinese geological case.

Contribution

It presents a new inversion technique for estimating the three-dimensional geometry of heat production interfaces in the lithosphere based on surface heat flow observations.

Findings

The heat production interface in the Ordos block varies unevenly over dozens of kilometers.

The derived heat flow model accurately fits geological and tectonic constraints.

The method effectively estimates the 3D geometry of heat production interfaces.

Abstract

Obtaining the heat production (HP) in the lithosphere has always been a challenge for the geotherms and evolution of continents. By transforming the nonlinear stable heat conduction equation into a linear Poisson's potential one, we propose a method to infer the HP in the stable continental lithosphere. This method estimates the HP through the inversion of the corresponding heat flow (HF) observations. Either the distribution of HP within the lithosphere or geometry of HP interfaces (even the both) can be inverted. Herein we focus on the inversion of the geometry of the HP interface. An analogical Parker-Oldenburg formula, which is often used in the inversion of potential field, is deduced for this purpose. This analogical formula is based on a relationship between the Fourier transform of the corresponding HF observations and the sum of the Fourier transform for the powers of the interface geometry. When the mean depth of the HP interface and the HP contrast between the two media are given, one to three-dimensional geometry of the HP interface can be iteratively calculated. As a case study, we construct a HP model for the lithosphere of the Ordos geological block and its adjacent area in China, in which three-dimensional geometry of the upper crustal HP interface is estimated. It is found that the geometry of this HP interface distribute uneven in a magnitude of dozens of km. With this HP model, the geotherms for the Ordos geological block and its adjacent area is calculated further, which fit the constraints from the studies on the xenolith and tectonics well.