Lithospheric electrical structure beneath the Cathaysia Block in South China and its tectonic implications

Ye, Cheng; Han, Bo; Li, Yiman; Jun, Guo; Hu, Xiangyun

doi:10.1016/j.tecto.2021.228981

Cited by 19 publications

(14 citation statements)

References 59 publications

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“…The final model shows a series of highly conductive anomalies (1-30 Ωm) labeled C1-C4 and a highly resistive anomaly (greater than 1,000 Ωm) marked R. The upper crust beneath the Cathaysia Block and the Wuyi-Yunkai Orogen is dominated by high-resistivity cover (R), which is interposed with low-resistivity features, mainly within the fault zone. Similar crustal structures have also been imaged in other areas of the South China Block (Cheng et al, 2021;Li et al, 2022;Xu et al, 2019;Yin et al, 2021).…”

Section: Inversion Resultssupporting

confidence: 72%

“…According to the temperature model, the temperature of the Moho is approximately 600°C (Figure 6c, Sun et al., 2013), which is lower than the melting temperature of water‐bearing granite (Puziewicz & Johannes, 1990). Thus, the conductor C3 has been interpreted as interconnected saline fluids, possibly derived from either the partial melting of the uppermost mantle following the dehydration of the subducting Paleo‐Pacific slab (Cheng et al., 2021; P. Zhou, Xia, et al., 2020) or the metamorphism‐induced dehydration of sandy argillaceous rocks in the lower crust (Connolly & Thompson, 1989; Schorn, 2018; Thiel et al., 2016). Preexisting faults act as fluid pathways, and both the reaction of hydrothermal fluids with rock and the extension of the crust caused by upwelling of the mantle trigger dynamic, permeable networks.…”

Section: Discussionmentioning

confidence: 99%

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Magnetotelluric Evidence for Lithospheric Alteration Beneath the Wuyi‐Yunkai Orogen: Implications for Thermal Structure of South China

Kong

et al. 2022

Geochem Geophys Geosyst

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The South China Block is an important Precambrian terrane in East Asia that formed during the early Neoproterozoic when the Yangtze Craton in the NW merged with the Cathaysia Block in the SE along the Jiangnan Orogen (Chen et al., 1991;Wang et al., 2007;Zhao, 2015). The South China Block has experienced multiple episodes of tectonomagmatism, which were accompanied by strong deformation and extensive metamorphism and migmatization (Li, 2000;Wang et al., 2013). Since the early Yanshanian (∼205-135 Ma), the tectonic setting of the South China Block has involved intracontinental lithospheric extension and asthenospheric upwelling with the former resulting in the emplacement of Mesozoic (∼230-66 Ma) granites over a large area of South China (Li et al., 2014). These Mesozoic granites, especially those emplaced since the Late Mesozoic (∼66 Ma), are widely exposed at the surface along the NE-NNE -trending structural belts (Chen et al., 1991;Li, 2000).

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Section: Inversion Resultssupporting

confidence: 72%

Section: Discussionmentioning

confidence: 99%

Magnetotelluric Evidence for Lithospheric Alteration Beneath the Wuyi‐Yunkai Orogen: Implications for Thermal Structure of South China

Kong

et al. 2022

Geochem Geophys Geosyst

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“…The southeast Chinese mainland is characterized by widespread Jurassic-Cretaceous granitic magmatism (Figures 1B,C) associated with more than 500 hot springs exposed along a series of NE-trending faults, with temperatures of 50 °C-100 °C (Pei and Hong, 1995;Jiang et al, 2019). According to recent broadband magnetotelluric (MT) results, no magma chamber or partial melt exists beneath the geothermal systems, and radiogenic heat produced from decaying radioactive elements in the crust is the heat source of southeastern China (Cheng et al, 2021). Therefore, the depth of circulation controlled by active faults could be a critical factor affecting reservoir temperatures.…”

Section: Introductionmentioning

confidence: 99%

Geochemical Characteristics of Hydrothermal Volatiles From Southeast China and Their Implications on the Tectonic Structure Controlling Heat Convection

Tian

Zhou

et al. 2021

Front. Earth Sci.

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Hot springs and igneous rocks are present widely in southeast China, influenced by the subduction of the Western Pacific and Philippine Sea Plates. This study reports on new data of chemical compositions and He–Ne–C isotopes for gas samples from representative hot springs and wells in the Guangdong and Fujian provinces to identify the origin of hydrothermal volatiles and provide insight into geothermal tectonic affinities. The primary hydrothermal volatile component from southeast China is atmospheric N2, with a volumetric percentage of 82.19%–98.29%. It indicates medium-low temperature geothermal systems where geothermal fluids suffered a shallow circulation in closed fracture systems. Low CO2 and CH4 contents and their depleted δ13C values confirmed the small number of deep-derived components in the study area. However, spatially discernible geochemical characteristics imply enhanced hydrothermal fluid convection in the adjacent area of the two provinces, including the Fengshun, Zhangzhou, Longyan, and Sanming geothermal fields. Specifically, the He–Ne isotopes from this area exhibit mantle He contribution of more than 10% and mantle heat flow accounts for more than half of the total heat flow. Moreover, according to the thermal background calculations, the highest heat flow value of 77.7 mW/m2 is indicated for the Zhangzhou geothermal area and the lowest value of 54.7 mW/m2 is indicated for the Maoming geothermal area. Given the epicenter distributions and the corresponding earthquake magnitudes, the NE-trending faults are heat-control tectonic structures and their intersections with the NW-trending faults provided expedite channels for geothermal fluids rising to the surface. Therefore, the preferred development potential of geothermal resources can be expected in the adjacent area of the two provinces where two sets of active faults crossed. This study provides critical information on understanding the geothermal distribution controlled by the tectonic structure in southeast China.

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“…They are thought to be channels for the subduction of mantle matter, resulting in a series of low resistivity layers in the crust and upper mantle. Recent 3D MT interpretation of the Meizhou-Shantou section (Line 2, Figure 3) shows that the low resistivity zones are mainly related to regional deep fault systems, rather than high-temperature heat sources of partial melt (Han, 2012;Cheng et al, 2021). 2D MT interpretations in the Huizhou (Line 3, Figure 3) and Yangjiang (Line 4, Figure 3) areas of Guangdong province indicate that low velocity zones exist at depths of 15-30 km and 35-60 km respectively.…”

Section: Low Resistivity Zones In the Upper Crust And High Temperature Heat Sourcementioning

confidence: 99%

Existence of High Temperature Geothermal Resources in the Igneous Rock Regions of South China

Tian

et al. 2021

Front. Earth Sci.

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Large areas of Yanshan period granites with high heat production values (3–10 μW/m3) and mantle plume around Hainan province co-exist in Igneous Rocks Regions of South China (IRRSC). Surface manifestations are mainly warm/hot springs with temperatures below 90 °C and no typical phenomenon of high temperature resources have been observed. The main objective of this paper is to discuss the existence of high temperature geothermal resources and their possible locations under this kind of geothermal and tectonic background by analysis of high temperature heat sources, borehole temperature measurement, and reservoir temperature estimation. Two possible partial melts of the magma chamber were detected as high temperature heat sources in the Southern Leizhou Peninsular and North Hainan Island at a depth of 8–15 km. Other low resistivity zones in the upper crust are more likely caused by fluid in the formations or faults but not high temperature heat sources. This was also verified by borehole temperature measurement in these two areas, with maximum formation temperatures of 211°C and 185°C found, respectively. Reservoir temperatures from fluid geothermometers show lower temperatures of between 110–160°C for typical geothermal fields over the IRRSC but not in the Southern Leizhou Peninsular and Northern Hainan Island. In all, high temperature geothermal resources may be found in the Southern Leizhou Peninsular and on Northern Hainan Island.

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Lithospheric electrical structure beneath the Cathaysia Block in South China and its tectonic implications

Cited by 19 publications

References 59 publications

Magnetotelluric Evidence for Lithospheric Alteration Beneath the Wuyi‐Yunkai Orogen: Implications for Thermal Structure of South China

Magnetotelluric Evidence for Lithospheric Alteration Beneath the Wuyi‐Yunkai Orogen: Implications for Thermal Structure of South China

Geochemical Characteristics of Hydrothermal Volatiles From Southeast China and Their Implications on the Tectonic Structure Controlling Heat Convection

Existence of High Temperature Geothermal Resources in the Igneous Rock Regions of South China

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