Analysis of hot-dry geothermal resource potential in southeastern Guangxi

doi:10.13745/j.esf.2020.1.9

Abstract

Abstract:

As an important part of geothermal resource, hot dry rock (HDR) is regarded as future clean energy with great developmental prospect and research value. Here, we studied southeastern Guangxi by re-examining the basic geological, geophysical and geochemical data. We carried out field investigations of tectonic-magmatic-sedimentary formation system, lithospheric structure, characteristics of present-day geothermal field and distribution of earthquakes and hot springs to explore the potential of dry-heat geothermal resources in southeastern Guangxi. The results show that the lithosphere is relatively thin with two low-velocity layers about 6 and 2 km thick at above 25 and 6-8 km, respectively, indicating presence of slippage type ductile shears and high temperature geological bodies. In this area, Indosinian granites can provide stable supply of radiogenic heat materials (mean U concentration 5.41×10^-6; Th 18.38×10^-6; K₂O 4.43%), whilst Cenozoic volcanic activities (OIB) provide a channel for the upwelling of deep thermal material while replenishing large amounts of geothermal energy. Indeed, we observed obvious geothermal anomalies in southeastern Guangxi: in Beihai-Nanning, terrestrial heat flow was at 80-100 mW/m²with geothermal gradient above 30 ℃/km; in Qinzhou and Hepu, Mesozoic-Cenozoic fault basins possess rich HDR geothermal resources that the sedimentary cap was of low cracking, porosity and thermal conductivity. Our research of dry heat geothermal potential will assist energy structural adjustment, ecological environmental optimization and industrial transformation and upgrading in Guangxi.

Key words: hot dry rock (HDR), resource potential, low-velocity layers, fault basins, southeastern Guangxi

CLC Number:

P314.2

SUN Minghang, LIU Demin, KANG Zhiqiang, GUAN Yanwu, LIANG Guoke, HUANG Xiqiang, YE Jiahui, GUO Shangyu, SUN Xingting, TANG Wei, FENG Minhao. Analysis of hot-dry geothermal resource potential in southeastern Guangxi[J]. Earth Science Frontiers, 2020, 27(1): 72-80.

Figures/Tables 6

Fig.1 Partition map of geotectonic elements of Guangxi (a) and distribution characteristics of Terrestrial basins in Southeastern Guangxi (b)

Table 1 Contents of radioactive elements of Early and Middle Triassic acid magmatic and Quaternary basic volcanic rocks

Fig.2 Map showing the distribution of above Ms 4 earthquakes in Guangxi and surrounding areas (since 1936)

Fig.3 Map showing the distribution of seismic profiles and source depths in the study area

Fig.4 Model of synthesized speed of the blasting earthquake in Liuzhou. Modified after [49].

Fig.5 Distribution of geothermal resources in Guangxi

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