The eastern Tibetan Plateau geothermal belt, western China: Geology, geophysics, genesis, and hydrothermal system
The eastern Tibetan Plateau geothermal belt, western China: Geology, geophysics, genesis, and hydrothermal system
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DOI：
10.1016/j.tecto.2017.08.035
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发表时间：
2017-10
期刊：
影响因子：
2.9
通讯作者：
Xianchun Tang;Jian Zhang;Z. Pang;Shengbiao Hu;Jiao Tian;Shu-jing Bao
中科院分区：
文献类型：
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作者：
Xianchun Tang;Jian Zhang;Z. Pang;Shengbiao Hu;Jiao Tian;Shu-jing Bao
青藏高原东部地热带位于98-102°E，28-32°N，属地中海-喜马拉雅地热带东段。最近，在ETGB中发现了大约248个天然温泉。超过60%的温泉温度超过40 °C，11个温泉的温度超过当地的水沸点。利用氦同位素、重力、磁力和地震资料，分析了该带的热结构特征，以及热液活动与热动力学的关系。结果表明：（1）248个温泉可划分为康定-炉霍地热田、理塘-甘孜地热田和巴塘-乡城地热田三个地热田。BGF和LGF具有热壳和暖地幔的特征，具有较高的热通量（66.26 mW/m2）和较高的壳源热通量占总热通量的比例（47.46-60.62%）。KGF具有壳冷幔热的特点，具有较高的热通量和较低的Qc/Qm;（2）存在一个相对高出4-6 m的重力大地水准面异常穹丘，与ETGB相对应。BGF和LGF热液活动区存在西北-东南向张应力区和中上地壳隆起区;（3）在ETGB之下13-30 km处的中下地壳中存在一层厚度为8-10 km的低速异常层（Vp<5.8km/s，Vs<3.2km/s）、高泊松比（> 2.5）、高电导率（~ 10 Ω·m）和高温（850-1000 °C）。最后，根据热源和地质地球物理背景，提出了新疆东天山康定型和巴塘型热液系统模式。
The eastern Tibetan Plateau geothermal belt (ETGB), which is located in 98–102°E, 28–32°N, belongs to the eastern part of the Mediterranean–Himalayan geothermal belt. Recently, about 248 natural hot springs have been found in the ETGB. > 60% of these springs have temperatures of > 40 °C, and 11 springs have temperature above the local water boiling point. Using the helium isotopic data, gravity, magnetic and seismic data, we analyzed the thermal structure and the relationship between hydrothermal activity and geothermal dynamics of the ETGB. Results show that: (1) the 248 springs can be divided into three geothermal fields: Kangding–Luhuo geothermal field (KGF), Litang–Ganzi geothermal field (LGF) and Batang–Xiangcheng geothermal field (BGF). The BGF and LGF have hot crust and warm mantle, and are characterized by the higher heat flux (66.26 mW/m2), and higher ratios of crust-derived heat flux to total flux (47.46–60.62%). The KGF has cool crust and hot mantle, and is characterized by the higher heat flux and lower Qc/Qm; (2) there is a relatively 4–6 m higher gravimetric geoid anomaly dome which is corresponding with the ETGB. And in hydrothermal activity areas of the BGF and LGF, there is a northwest – southeast-trending tensile stress area and the upper–middle crust uplift area; (3) an abnormal layer exists in the middle–lower crust at a depth of 13–30 km beneath the ETGB, and this layer is 8–10 km thick and is characterized by lower velocity (Vp< 5.8 km/s, Vs< 3.2 km/s), high Poisson's ratio (> 2.5), high conductivity (~ 10 Ω·m) and high temperature (850–1000 °C). Finally, based on the heat source and geological and geophysical background, we propose Kangding-type and Batang-type hydrothermal system models in the ETGB.