Exploring the Driving Mechanisms Behind Variations in <scp> ⁸⁷ Sr </scp> / <scp> ⁸⁶ Sr </scp> Ratios in Neoproterozoic–Cambrian Oceans

ABSTRACT The long‐term evolution of seawater strontium isotope ratios ( 87 Sr/ 86 Sr) serves as a critical archive for reconstructing paleogeographic configurations, climatic shifts, and biological evolution. However, the driving mechanisms behind 87 Sr/ 86 Sr variations during the Neoproterozoic–Cambrian transition (700–500 Ma) remain debated, owing to the interplay of multiple geological processes including supercontinental fragmentation, amalgamation, orogenic activity, and volcanic events. This study analyses 486 87 Sr/ 86 Sr measurements from global marine carbonates spanning 700–500 Ma, integrated with temporal records from 89 orogenic belts worldwide. The refined seawater 87 Sr/ 86 Sr curve reveals a three‐phase ascending trend: 700–635 Ma: The breakup of Rodinia and the simultaneous assembly of Gondwana created a low marine 87 Sr/ 86 Sr ratio, yet it still exhibited an upward trend. 635–540 Ma: Progressive ratio increases align with the Gondwana supercontinent assembly, driven by intensified orogenic uplift that exposed radiogenic continental crust to weathering. 540–500 Ma: Accelerated ratio elevation correlates with final Gondwana block amalgamation, volcanic degassing, and greenhouse‐induced climatic conditions that amplified continental silicate weathering fluxes. This phased model highlights pre‐Cambrian orogenesis as a pivotal precursor to the Cambrian Explosion. The convergence of Gondwana continental blocks, coupled with Cambrian greenhouse climates, dramatically enhanced terrestrial weathering efficiency. The resultant surge in nutrient delivery (e.g., phosphorus) to oceans likely created biogeochemical thresholds critical for triggering the Cambrian biospheric radiation. These findings establish tectonically mediated weathering‐climate feedbacks as central regulators of Earth's biogeochemical transitions during this pivotal interval.