Yiping Wu

Most of the helium-rich gas fields in the globe are in the peripheral rift of ancient craton, but the mechanism for helium accumulation is unique and more complicated than the petroleum system. For instance, since the discovery of the helium-rich hot spring in the Tanzania Craton (metamorphic basement) in 1967, no significant helium field has been found. This research explores the mechanism of helium enrichment and buildup in the periphery rift of an ancient craton using data from gravitational-magneto-electric-seismic-geochemical-logging. According to studies, four components are required for the buildup of helium-rich pools: a long-lasting stable ancient basement holding uranium and thorium; recent tectonic events; efficient secondary migration pathways; and efficient helium-capture traps. Five mechanisms, including mantle plume upwelling, helium generation and accumulation, vertical advection conveying helium, trapping helium, and leftover helium overflowing the surface, have been involved in the release of helium from the Tanzania craton's periphery. The Lupa margin fault controls the semi-graben TRM (Tanganyika-Rukwa-Malawi) shear zone, which has the nature of a strike-slip pull-apart and is in the Rukwa basin. Three rifts occurred in the basin: the Paleozoic Karoo Rift, the Mesozoic Intraplate Rift, and the Cenozoic Rift, the latter of which was crucial in regulating helium migration and buildup. In the Rift Basin, there are two different types of helium accumulation models: one involves inorganic gas and helium in the same reservoir from the same source, and the other involves methane gas and helium in the same reservoir from different sources. The first of these is the primary charging model, and the second primarily occurs along the syncline axis of the basin. The optimal configuration for helium accumulation is found in the BMFCs in the outer rift of the prehistoric Tanzanian craton, where the accumulation coefficient is 0.48%. The 96 billion cubic meters of risked untapped helium geological potential have turned the rift basin's desirable exploration objectives. The study points out the route for helium exploration and the favorable areas for the peripheral rift of the ancient global craton.