Studies on the relationships of the Curie surface with heat flow and crustal structures in Yunnan Province, China, and its adjacent areas

Abstract

A Curie surface indicates the distribution of the thermal fields underground, providing a clear marker for the thermodynamic effect in the crust and mantle. In this paper, based on a geomagnetic field model (NGDC-720) and aeromagnetic data, we use power spectrum analysis of magnetic anomalies to estimate the Curie surface in Yunnan Province, China, and its adjacent areas. By combining the distribution of the Curie surface with regional heat flow, the geothermal gradient, crustal wave velocity ratio anomalies, high-conductivity layer anomalies, and the Moho surface, we reveal the connection between the undulation of the magnetic basement and the crustal structures. The results indicate that the uplift and depression of the Curie surface in the research area are distinct. The Curie surface is approximately inversely correlated to the surface heat flow. The Lijiang-Jianchuan-Baoshan-Tengchong and Jianchuan-Chuxiong-Kunming-Yuxi zones are two Curie surface uplift zones, and their crust-mantle heat flows are relatively high. The Curie surface uplift zone along the Lijiang-Xiaojinhe fault and Red River fault is consistent with the heading direction of the fault zone and is partially in agreement with the eastward mass flow of the Tibetan Plateau. The Curie surface uplift zone is consistent with the high wave velocity ratio and high-conductivity layer anomaly region of the crust. The depth of the Curie surface is less than the depth of the Moho surface.

Diffuse Deformation in the SE Tibetan Plateau: New Insights From Geodetic Observations

“…Journal of Geophysical Research: Solid Earth measurement in our study area is 67.5 mW/m 2 , higher than the average value of 63 mW/m 2 for Chinese mainland (Hu et al, 2000;Wen et al, 2019). This indicates higher crustal temperature, higher geothermal gradient, and thinner brittle upper crust in the SE and eastern Tibetan Plateau, which would lead to smaller fault spacing (Yang et al, 2020).…”

Determination of Conrad and Curie point depth relationship with the variations in lithospheric structure, geothermal gradient and heat flow beneath the central main Ethiopian rift

“…The Curie point depth (CPD) is the theoretical surface thought to have been formed by ferromagnetic minerals in crustal rocks becoming paramagnetic assumed to have a temperature of ∼580 °C above which ferromagnetic minerals loss their magnetism and considered to be an indicator of the bottom interfaces of magnetized bodies ( Wen et al., 2019 ).…”

“…Spectral analysis of magnetic data and GMSYS 3D inversion ( Popowski et al., 2006 ) of gravity data is employed here as there is no previous published data regarding for the determination of the CPD and Conrad depth in the central main Ethiopian rift (CMER). Finally, we estimate the variations of geothermal gradient and heat flow from the CPD variations (e.g., Maden, 2010 ; Kasidi and Nur, 2012 ) and discuss the CPD results in relation with geothermal gradient variation, heat flow variation, crustal wave velocity ratio anomalies (e.g., Wen et al., 2019 ), lithospheric structures including Moho and Conrad depths.…”

Diffuse deformation in the SE Tibetan Plateau: New insights from geodetic observations

“…Earthquakes (M ≥ 2.5) mostly occurred above depths of~25 km (Figures 2c and 7), and we suggest this depth may mark the seismogenic thickness and brittle-ductile transition in the SE Tibetan Plateau. The average surface heat flow 10.1029/2020JB019383 Journal of Geophysical Research: Solid Earth measurement in our study area is 67.5 mW/m 2 , higher than the average value of 63 mW/m 2 for Chinese mainland (Hu et al, 2000;Wen et al, 2019). This indicates higher crustal temperature, higher geothermal gradient, and thinner brittle upper crust in the SE and eastern Tibetan Plateau, which would lead to smaller fault spacing (Yang et al, 2020).…”