Present-day geothermal regime of the Uliastai Depression, Erlian Basin, North China

Wei Xu,Junhe Chang,Shaopeng Huang,Jiong Zhang,Yongshui Zhou,Ruyang Yu,Yinhui Zuo

doi:10.1177/0144598718785970

Abstract

In this study, we calculated the present-day terrestrial heat flow of the Uliastai Depression in Erlian Basin by using systematical steady-state temperature data obtained from four deep boreholes and 89 thermal conductivity measurements from 22 boreholes. Then, we calculated the lithospheric thermal structure, thermal lithospheric thickness, and lithospheric thermo-rheological structure by combining crustal structure, thermal conductivity, heat production, and rheological parameter data. Research from the Depression shows that the present-day terrestrial heat flow ( qs) is 86.3 ± 2.3 mW/m2, higher than the average of 60.4 ± 12.3 mW/m2 of the continental area of China. Mantle heat flow ( qm) in the Depression ranges from 33.7 to 39.3 mW/m2, qm/ qs ranges from 40 to 44%, show that the crust plays the dominant position in the terrestrial heat flow. The thermal thickness of the lithosphere is about 74–88 km and characterized by a “strong crust–weak mantle” rheological characteristic. The total lithospheric strength is 1.5 × 1012 N/m under wet mantle conditions. Present-day geothermal regime indicates that the Uliastai Depression has a high thermal background, the activity of the deep-seated lithosphere is relatively intense. This result differs significantly from the earlier understanding that the area belongs to a cold basin. However, a hot basin should be better consistent with the evidences from lithochemistry and geophysical observations. The results also show the melts/fluids in the study area may be related to the subduction of the Paleo-Asian Ocean. The study of the geothermal regime in the Uliastai Depression provides new geothermal evidence for the volcanic activity in the eastern part of the Central Asian Orogenic Belt and has significant implications for the geodynamic characteristics.

Highlights

The Erlian Basin is located in the Xing’an-Mongolia Orogenic Belt between the North China Plate and the Siberian Plate (Figure 1)
We reevaluated the present-day terrestrial heat flow of the Uliastai Depression in Erlian Basin based on the borehole temperature and thermal conductivity data
We calculated the terrestrial heat flow of the Uliastai Depression based on the systematical steady-state temperature data from four deep boreholes and 89 thermal conductivity measurements from 22 boreholes (Table 1, the detailed data see in Xu et al)

Summary

Introduction

The Erlian Basin is located in the Xing’an-Mongolia (or Xing-Meng) Orogenic Belt between the North China Plate and the Siberian Plate (Figure 1). We reevaluated the present-day terrestrial heat flow of the Uliastai Depression in Erlian Basin based on the borehole temperature and thermal conductivity data. We calculated the terrestrial heat flow of the Uliastai Depression based on the systematical steady-state temperature data from four deep boreholes and 89 thermal conductivity measurements from 22 boreholes (Table 1, the detailed data see in Xu et al (in preparation)). We calculated thermal structure of the lithosphere based on the heat flow values, the heat production rate, and the thickness of crustal layering (Table 1). The mantle heat flow of the Uliastai Depression is significantly higher than most of the cratons in global, most of them range from 10 to 20 mW/m2 (Gupta, 1993; Jaupart and Mareschal, 1999; Roy and Jean-Claude, 2011) This high mantle heat flow may result from the deep-seated processes in the upper mantle and reflects the tectonic instability of the crust.

2.84 Granitite

Discussion

Conclusions