Reassessment of the Distribution of Mantle CO ₂ in the Bohai Sea, China: The Perspective from the Source and Pathway System

Research on the distribution of mantle CO 2 should involve comprehensive analysis from CO 2 source to accumulation.The crust-mantle pathway system is the key controlling factor of the distribution of mantle CO2,but has received little attention.The pathway system and controlling factors of CO 2 distribution in the Bohai Sea are analyzed using data on fault styles and information on the mantle and lithosphere.The relation between volcanic rocks and the distribution of mantle CO 2 is reassessed using age data for CO 2 accumulations.The distribution of mantle CO 2 is controlled by uplift of the asthenosphere and upper mantle,magma conduits in the mantle and fault systems in the crust.Uplifted regions of the asthenosphere are accumulation areas for CO 2 .The area with uplift of the Moho exhibits accumulation of mantle CO 2 at depth.CO 2 was mainly derived from vertical migration through the upper mantle and lower crust.The fault style in the upper crust controls the distance of horizontal migration and the locations of CO 2 concentrations.The distribution of mantle CO 2 and volcanic rocks are not the same,but both probably followed the same pathways sometimes.Mantle CO 2 in the Bohai Sea is concentrated in the Bozhong sag and the surrounding area,particularly in a trap that formed before 5.1 Ma and is connected to crustal faults（the Bozhang faults） and lithospheric faults（the Tanlu faults）.