Abstract: Helium generating potential of helium source rocks act as the primary element in generating helium resources.
Organic-rich shales and granites in the crust rich in uranium and thorium are good helium source rocks. Based on field geological surveys and core observations in the northern margin of Qaidam Basin, combined analysis of systematic element geochemistry and chronology data of different stratigraphic units in the area, this study investigated geochemical characteristics and heliumgenerating potential of the main helium source rock types in the Northern Qaidam Basin. The results show that the helium source rocks of the basement type of the Paleoproterozoic Dakendaban Group and the Early Paleozoic Tanjianshan Group display helium-generating intensity of 0.565×10^-12 cm³/（a·g）and 0.278×10^-12 cm³/（a·g）, respectively. Hercynian and Indosinian intrusive rocks and volcanic rocks occur in the basin margin. The helium-generating intensity of Hercynian and Indosinian volcanic rocks are 0.198×10^-12 cm³/（a·g） and 0.623×10^-12 cm³/（a·g）, while the Hercynian and Indosinian intrusive rocks show
helium-generating intensity of 0.217×10^-12 cm³/（a·g）and 0.348×10^-12 cm³/（a·g）, respectively. The main sedimentary helium source rocks in the northern margin of the Qaidam Basin are Carboniferous marine deposits and Jurassic continental strata with high uranium and thorium content. The Carboniferous series is widely distributed in the northern margin of Qaidam Basin and exhibits average abundance of U and Th of 8.70×10^-6 and 15.10×10^-6, respectively, and a helium-generating intensity of 1.483×10^-12 cm³/（a·g）. The middle and lower Jurassic shale series occur intermittently along the Altun Mountain and Qaidam margins, displaying average abundance of U and Th of 7.72×10^-6 and 20.21×10^-6, respectively, and a helium-generating intensity of 1.509×10^-12 cm³/（a·g）. Overall, this study lays a foundation for comprehensive helium resource geological surveys in the Qaidam Basin.

Key words: Northern Qaidam Basin, Helium source rock, Helium-producing potential, Igneous rocs, Geochemistry of elements