Abstract: The southwestern margin of the Yangtze Block is extensively intruded by Paleoproterozoic magmatic rocks; however, significant controversy persists regarding their tectonic setting and dynamic mechanisms. Gabbro, as the direct crystallization product of mafic magma, provides zircon U-Pb isotopic chronology data that can precisely constrain the timing of tectonothermal events. Furthermore, its major and trace element compositions effectively record the material exchange and energy transfer processes between the lithosphere and asthenosphere, offering critical geochemical constraints for discriminating tectonic environments. This paper presents a systematic isotopic chronological and geochemical study of the Dayaowan gabbro in the Dongchuan area. The results show that the zircon U-Pb age of the gabbro is (1 674 ± 16) Ma, indicating its emplacement during the Late Paleoproterozoic. The rock belongs to the subalkaline series, exhibiting flat or slightly right-inclined patterns in chondrite-normalized rare earth element (REE) diagrams. In primitive mantle-normalized trace element spider diagrams, it displays enrichment in large-ion lithophile elements (LILEs) including Ba, Sr, and La, along with relative depletion in high-field-strength elements (HFSEs) such as Nb, Ta, and Hf. These geochemical characteristics share affinities with both within-plate basalts (WPB) and enriched mid-ocean ridge basalts (E-MORB). Comprehensive analysis suggests that this magmatic activity likely formed in an intracontinental rift setting associated with mantle plume activity, representing a tectonic-magmatic thermal event response on the southwestern margin of the Yangtze Block during the breakup of the global Columbia Supercontinent.