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The northeastern Tibetan Plateau (NETP) is the most intensely uplifted deformation region in the Tibetan Plateau. The intense gas release caused by uplift has attracted widespread attention. In this study, we measured the soil gas concentrations (Rn and CO 2) and CO 2 fluxes from active faults and analysed the seismic tomography in the arcuate structure zone of the NETP. The results reveal that the concentrations and fluxes of Rn and CO 2 in the south area are higher than those in the north area. Factors such as rock types, meteorological conditions, and seismicity have limited influence on soil gas emissions. Instead, the uplift of the upper crust in the Tibetan Plateau plays a crucial role in determining the distribution of soil gases. Regions with high crack density (ε), saturation rate (ξ) and Poisson's ratio (σ) in the upper crust show stronger release, such as the epicenter of the Haiyuan M S 8.5 earthquake. The convergence zone of the arcuate structure zone with high crust uplift velocity is an intense release area with a rough total CO 2 output of ∼1.10 Mt.·yr−1. This output is twice the annual CO 2 output of the Wenchuan M S 8.0 earthquake rupture and one-fifth of the annual CO 2 output of Amiata volcano, Italy. [ABSTRACT FROM AUTHOR]

Fluid geochemistry in active fault zones has been proven to be sensitive to tectonic activity. The North China Craton (NCC) has attracted much attention because of its complex and intense tectonic activity. In this study, fluid geochemistry in the primary active fault zones in the NCC was investigated, including inference of its tectonic activity. Stronger degassing from soil and springs has been observed in the northeastern Tibetan Plateau (NETP) and the Zhang-Bo seismic zone (ZBSZ) than in the other seismic zones. Both geological soil gas and deep-derived gas (crust- or mantle-derived gas) from springs were concentrated there. Also, a comprehensive analysis has indicated that the development of new fractures might have occurred widely beneath the NETP and ZBSZ because of the strong regional tectonic activity there. The 3He/4He and 4He/20Ne of gas from the springs in the ZBSZ suggest that the low-velocity zone 20– 40 km deep might be a magmatic intrusion derived from the mantle. However, crust-derived gas accompanied with a negligible mantle-derived component has been detected in the Diebu-Bailongjiang fault (DBF), the West Qinling fault (WQLF), and the Liupanshan fault (LPSF) in the NETP. There, the occurrence of more new fractures was probable, in accordance with the obvious δ18O shift of the water from the springs in the fault zones. This suggests that a channel flow, also depicted by the low-velocity zone 20– 40 km deep, could have formed within the crust and that the probable leading front reached the LPSF. [ABSTRACT FROM AUTHOR]