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Meng B, Zhou S, Li J, Sun Z. Mantle-Derived Helium Distribution and Tectonic Implications in the Sichuan-Yunnan Block, China. ACS OMEGA 2021; 6:30674-30685. [PMID: 34805695 PMCID: PMC8600645 DOI: 10.1021/acsomega.1c04533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
The geochemical characteristics of mantle degassing observed on the surface of the earth can indicate the origin and migration path of mantle fluids. Compared with the plate boundary tectonic environment, the intraplate tectonic environment does not have a large number of active volcanoes and active faults, and the observation of mantle volatiles in hot spring gas is relatively limited. We selected the Sichuan-Yunnan block to discuss mantle degassing based on the carbon and noble gas isotopes of the spring gases and previous studies on the fault slip rate and geophysical research. A total of five hot spring gas samples (including two free gases and three dissolved gases) were collected from the Sichuan-Yunnan block. Chemical and isotopic compositions were analyzed in N2-dominant hot spring gases. The 3He/4He ratio (0.068-0.541 R a) indicates the occurrence of mantle-derived helium throughout the Sichuan-Yunnan block, which has been diluted by a crustal radiogenic 4He component. The occurrence of mantle-derived helium in the study areas ranges from 0.74 to 5.67%. The lower proportion of mantle-derived helium in YNWQ and HGWQ than that in other spring gases near the Jinghe-Qinghe fault may be caused by the smaller scale of fault around YNWQ and HGWQ than the Jinghe-Qinghe fault. The correlation between 4He, 20Ne, and N2 concentrations implies a common trapping mechanism for 4He, 20Ne, and N2 in hot spring gases. The 40Ar/36Ar ratios and N2/Ar ratios indicate that N2 and Ar are mostly meteoric, and YNWQ and HGWQ have more crustal-derived Ar contribution (40.56 and 51.49%, respectively). The δ13C(CO2)o values calculated by Rayleigh fractionation and CO2 concentration suggest that CO2 has inorganic and organic origins. The plot of R c/R a versus δ13C(CO2) indicates that the spring gas CO2 origin in the Sichuan-Yunnan block is mainly derived from mixing of limestone and organic sediments with minor mantle CO2. The δ13C(CH4) versus CH4/3He values indicate that the origin of methane is thermogenic and microbial oxidation. The low mantle-derived helium distribution pattern is most likely controlled by the weak fault activity rate, the small fault scale, and not obvious magmatic activity in the Sichuan-Yunnan block.
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Affiliation(s)
- Bingkun Meng
- Northwest
Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
- Key
Laboratory of Petroleum Resources, Gansu Province, Lanzhou 730000, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
| | - Shixin Zhou
- Northwest
Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
- Key
Laboratory of Petroleum Resources, Gansu Province, Lanzhou 730000, China
| | - Jing Li
- Northwest
Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
- Key
Laboratory of Petroleum Resources, Gansu Province, Lanzhou 730000, China
| | - Zexiang Sun
- Northwest
Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
- Key
Laboratory of Petroleum Resources, Gansu Province, Lanzhou 730000, China
- University
of Chinese Academy of Sciences, Beijing 100049, China
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Zhang M, Guo Z, Xu S, Barry PH, Sano Y, Zhang L, Halldórsson SA, Chen AT, Cheng Z, Liu CQ, Li SL, Lang YC, Zheng G, Li Z, Li L, Li Y. Linking deeply-sourced volatile emissions to plateau growth dynamics in southeastern Tibetan Plateau. Nat Commun 2021; 12:4157. [PMID: 34230487 PMCID: PMC8260613 DOI: 10.1038/s41467-021-24415-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 06/09/2021] [Indexed: 02/06/2023] Open
Abstract
The episodic growth of high-elevation orogenic plateaux is controlled by a series of geodynamic processes. However, determining the underlying mechanisms that drive plateau growth dynamics over geological history and constraining the depths at which growth originates, remains challenging. Here we present He-CO2-N2 systematics of hydrothermal fluids that reveal the existence of a lithospheric-scale fault system in the southeastern Tibetan Plateau, whereby multi-stage plateau growth occurred in the geological past and continues to the present. He isotopes provide unambiguous evidence for the involvement of mantle-scale dynamics in lateral expansion and localized surface uplift of the Tibetan Plateau. The excellent correlation between 3He/4He values and strain rates, along the strike of Indian indentation into Asia, suggests non-uniform distribution of stresses between the plateau boundary and interior, which modulate southeastward growth of the Tibetan Plateau within the context of India-Asia convergence. Our results demonstrate that deeply-sourced volatile geochemistry can be used to constrain deep dynamic processes involved in orogenic plateau growth.
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Affiliation(s)
- Maoliang Zhang
- grid.33763.320000 0004 1761 2484Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China
| | - Zhengfu Guo
- grid.9227.e0000000119573309Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences (CAS), Beijing, China ,grid.9227.e0000000119573309CAS Center for Excellence in Life and Paleoenvironment, Beijing, China
| | - Sheng Xu
- grid.33763.320000 0004 1761 2484Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China
| | - Peter H. Barry
- grid.56466.370000 0004 0504 7510Marine Chemistry and Geochemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA USA
| | - Yuji Sano
- grid.33763.320000 0004 1761 2484Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China ,grid.26999.3d0000 0001 2151 536XAtmosphere and Ocean Research Institute, The University of Tokyo, Chiba, Japan ,grid.278276.e0000 0001 0659 9825Present Address: Center for Advanced Marine Core Research, Kochi University, Kochi, Japan
| | - Lihong Zhang
- grid.449571.a0000 0000 9663 2459School of Geology and Geomatics, Tianjin Chengjian University, Tianjin, China
| | - Sæmundur A. Halldórsson
- grid.14013.370000 0004 0640 0021NordVulk, Institute of Earth Sciences, University of Iceland, Reykjavík, Iceland
| | - Ai-Ti Chen
- grid.19188.390000 0004 0546 0241Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC
| | - Zhihui Cheng
- grid.12981.330000 0001 2360 039XSchool of Earth Science and Engineering, Sun Yat-sen University, Guangzhou, China
| | - Cong-Qiang Liu
- grid.33763.320000 0004 1761 2484Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China
| | - Si-Liang Li
- grid.33763.320000 0004 1761 2484Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China
| | - Yun-Chao Lang
- grid.33763.320000 0004 1761 2484Institute of Surface-Earth System Science, School of Earth System Science, Tianjin University, Tianjin, China
| | - Guodong Zheng
- grid.9227.e0000000119573309Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Zhongping Li
- grid.9227.e0000000119573309Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Liwu Li
- grid.9227.e0000000119573309Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China
| | - Ying Li
- grid.450296.c0000 0000 9558 2971Institute of Earthquake Forecasting, China Earthquake Administration, Beijing, China
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Joint Inversion of GPS, Leveling, and InSAR Data for The 2013 Lushan (China) Earthquake and Its Seismic Hazard Implications. REMOTE SENSING 2020. [DOI: 10.3390/rs12040715] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
On 20 April 2013, a moment magnitude (Mw) 6.6 earthquake occurred in the Lushan region of southwestern China and caused more than 190 fatalities. In this study, we use geodetic data from nearly 30 continuously operating global positioning system (GPS) stations, two periods of leveling data, and interferometric synthetic aperture radar (InSAR) observations to image the coseismic deformation of the Lushan earthquake. By using the Helmert variance component estimation method, a joint inversion is performed to estimate source parameters by using these GPS, leveling, and InSAR data sets. The results indicate that the 2013 Lushan earthquake occurred on a blind thrust fault. The event was dominated by thrust faulting with a minor left-lateral strike–slip component. The dip angle of the seismogenic fault was approximately 45.0°, and the fault strike was 208°, which is similar to the strike of the southern Longmenshan fault. Our finite fault model reveals that the peak slip of 0.71 m occurred at a depth of ~12 km, with substantial slip at depths of 6–20 km. The estimated magnitude was approximately Mw 6.6, consistent with seismological results. Furthermore, the calculated static Coulomb stress changes indicate that the 2013 Lushan earthquake may have been statically triggered by the 2008 Wenchuan earthquake.
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Source Parameter Estimation of the 2009 Ms6.0 Yao’an Earthquake, Southern China, Using InSAR Observations. REMOTE SENSING 2019. [DOI: 10.3390/rs11040462] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
On 9 July 2009, an Ms6.0 earthquake occurred in mountainous area of Yao’an in Yunnan province of Southern China. Although the magnitude of the earthquake was moderate, it attracted the attention of many Earth scientists because of its threat to the safety of the population and its harm to the local economy. However, the source parameters remain poorly understood due to the sparse distribution of seismic and GNSS (Global Navigation Satellite System) stations in this mountainous region. Therefore, in this study, the two L-band ALOS (Advanced Land Observing Satellite-1) PALSAR (Phased Array type L-band Synthetic Aperture Radar) images from an ascending track is used to investigate the coseismic deformation field, and further determine the location, fault geometry and slip distribution of the earthquake. The results show that the Yao’an earthquake was a strike-slip event with a down-dip slip component. The slip mainly occurred at depths of 3–8 km, with a maximum slip of approximately 70 cm at a depth of 6 km, which is shallower than the reported focal depth of ~10 km. An analysis of the seismic activity and tectonics of the Yao’an area reveals that the 9 July 2009 Yao’an earthquake was the result of regional stress accumulation, which eventually led to the rupture of the northwestern most part of the Maweijing fault.
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Locking Status and Earthquake Potential Hazard along the Middle-South Xianshuihe Fault. REMOTE SENSING 2018. [DOI: 10.3390/rs10122048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
By combining the seismogenic environment, seismic recurrence periods of strong historical earthquakes, precise locations of small–moderate earthquakes, and Coulomb stress changes of moderate–strong earthquakes, we analyze the potential locking status of a seismically quiet segment of Xianshuihe fault between Daofu County and Kangding City (SDK). The interseismic surface velocities between 1999 and 2017 are obtained from updated global positioning system (GPS) observations in this region. After removing the post-seismic relaxation effect caused by the 2008 Mw 7.9 Wenchuan earthquake that occurred around the fault segment, the observed velocities reveal a pronounced symmetric slip pattern along the SDK trace. The far field slip rate is 7.8 ± 0.4 mm/a, and the fault SDK is confirmed to be in an interseismic silent phase. The optimal locking depth is estimated at 7 km, which is perfectly distributed on the upper edge of the relocated hypocenters. A moment deficit analysis shows cumulative seismic moment between 1955 and 2018, corresponding to an Mw 6.6 event. Finally, based on a viscoelastic deformation model, we find that moderate–strong earthquakes in the surrounding area increase the Coulomb stress level by up to 2 bars on the SDK, significantly enhancing the future seismic potential.
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Fault Slip Rates and Seismic Moment Deficits on Major Faults in Ordos Constrained by GPS Observation. Sci Rep 2018; 8:16192. [PMID: 30385818 PMCID: PMC6212509 DOI: 10.1038/s41598-018-34586-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Accepted: 10/06/2018] [Indexed: 11/08/2022] Open
Abstract
The Ordos Block, surrounded by numerous active faults, is a relatively rigid but dangerous area with many strong historical earthquakes. We derive the block rotation velocity and fault slip rates in this area by using GPS data recorded from 1999 to 2007 and implementing an elastic block model. Instead of assuming vertical faults, as did most previous studies in and around Ordos, we use an improved method to invert for the fault dip angles and construct a closed 3-D fault system in our inversion. The predicted slip rates range from <1 mm/yr to ~ 10 mm/yr. Our results are roughly consistent with geological and other geodetic observations. Using the estimated slip rates, we also calculate the cumulative seismic moment due to fault locking and the released moment from historical earthquake catalogues. A comparison of the two quantities indicates that the Hetao Rift has an unreleased seismic moment equal to a Mw 7.9 earthquake, which is also indicated by frequent earthquakes above M6 after 1900.
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