Reconstruction of the Curie depth distribution on the Arabian Plate: Implications for its regional thermal structure

Abstract

Heat flow measurements in the Arabian Plate are inconsistent with anticipated heat flow levels and are not uniformly distributed. They originate mostly from shallow temperature measurements for geothermal surveys and are not specifically targeted for determining the thermal field at the lithosphere scale. We employed spectral analysis of aeromagnetic data based on the fractal distribution of sources to estimate the depth to Curie isotherm (580 °C) in 22 overlapping windows along a southwest-northeast oriented transect of 1000 km across the Arabian Plate. We used the estimate of depth to Curie isotherm and present depth to the lithosphere-asthenosphere boundary to constrain a set of geotherms and to predict surface heat flow and bulk radiogenic heat production across the Arabian Plate. The results indicate that the depth to Curie isotherm is relatively deep (37 km) at the center of the plate and becomes shallower westwards (22 km) and eastwards (27 km), in the Arabian Shield and the Arabian Platform, respectively. The estimated bulk radiogenic heat production in the Arabian Shield is relatively low (0.4 μW/m3) and increases gradually to 1.12 μW/m3 towards the eastern part of the plate. The estimated surface heat flow is low at the center of the plate (45.6 m/Wm2) and rises to about 65 m/Wm2 in the west of the Shield and also in the east of the plate. The average surface heat flow on the entire Arabian Shield is around 50 mW/m2, in accordance with the average heat flow observed on Late Precambrian crust worldwide, but contrasts with the heat flow measurements in the Saudi Arabian part (36 and 45 mW/m2). The elevation of the upper mantle as well as the relatively high radiogenic heat production in the crust can be considered as the causes of the higher level of heat flow at the eastern side of the platform. The results of our study provide a better understanding of the thermal structure of the Arabian Plate and show how potential field data can be employed as a constraint when calibrating basin models.