[S25-P] Poster

[S25-P-04] Terrestrial Heat flow and 1D Geoelectric Model of the Baiyinchagan Sag, Erlian Basin, Northern China

^○Jiong Zhang¹, Rao Fu¹, Yongshui Zhou⁵, Yi Wang³, Di Hu³, Yinhui Zuo⁴, Shaopeng Huang^1,2, Xiaoyin Tang¹, Ruyang Yu¹ (1.Institute of Global Environmental Change, Xi'an Jiaotong University, Xi'an, China, 2.Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, US, 3.Institute of Geology and Geophysics, Chinese Academy of Scinece, 4.Chengdu College of Geology, Chengdu, China, 5.Sinopec Zhongyuan Oilfield, Puyang, China)

The Baiyinchagan Sag is located in the western margin of the Erlian Basin, a Mesozoic rift basin in the collision suture zone of the Siberian Plate and North China Craton in northwest Inner Mongolia in northern China. Here we report preliminary analysis of new heat flow measurements in four deep boreholes and magnetotelluric soundings at these borehole sites. Subsurface temperature gradient varies from 35.6 to 45.4 degrees per kilometer in the selected boreholes between the depths from 200 to 2150 m. Thermal conductivities of 36 sedimentary and metamorphic rock samples fall in the range of 0.93-4.03 W/m/K. The mean of the measured heat flow values is 76 mW per suquare meter. Our new heat flow measurements are consistent with the recent report of Zuo et al. (2016, 75 mW per suquare meter), but substantially greater than the estimates of 43-66 mW per suquare meter registered for the Erlian Basin in the fourth edition of the Chinese heat flow data compilation (Jiang et al., 2016). One-dimensional Occam's inversion of the magnetotelluric sounding data shows that the uppermost 4 km layer of the rocks are low in electric resistivity (<100 Ωm), likely due to the fluid in the porous strata. A high resistance (>2000 Ωm) layer is located at the depth of 7-20 km. We are in the process of constructing the thermal structure of the lithosphere for the Baiyinchagan Sag based on the new measurements and other relevant geological and geophysical data. The geodynamic and petroleum resource implications of the lithospheric thermal structure will be discussed, and the results will be presented at the meeting.