Neoproterozoic multi-terrane convergence in South China and its resource implications

Key words: 
• South China Block /
• Neoproterozoic /
• Subduction-accretion /
• Multi-terrane convergence /
• Resource

Abstract: The Neoproterozoic Era is a crucial period for continental growth, reworking, and reshaping of the South China Block. The widespread Neoproterozoic rocks serve as the basement sequences for Phanerozoic South China Block. Understanding the Neoproterozoic crustal evolution of the South China Block is essential due to its implications for: i) regional resource and environment impacts, ii) the assembly and dispersal of Neoproterozoic supercontinents, and iii) subsequent “Cambrian explosion”. Here, we reviewed key geological records from the early-to-middle Neoproterozoic, including island arc magmatism, ophiolites, linearly-distributed continental-arc calc-alkaline magmatism, rapid endogenic recycling processes induced by ocean-continent subduction, subduction-zone metamorphism, accretionary rock complex, and extrusion-related deformation. We suggested the existence of a multi-terrane (or multi-microcontinent) structure in South China and its nearby regions during Neoproterozoic, with the terrane/microcontinent boundaries roughly defined by a series active- and passive-continent-margin rock units. We proposed the South China Block experienced a prolonged accretionary orogeny and consequent terrane/microcontinent amalgamation, accompanied by outward migration and reorganization of active continental margins. These Neoproterozoic subduction-accretion processes likely shaped the contemporary geological framework of the South China Block. More importantly, the Neoproterozoic convergent boundaries were preferentially involved in Phanerozoic crustal reworking and differentiation processes, and potentially played a pivotal role in Phanerozoic ore formation. This perspective may provide novel insights into the connections between Precambrian basement characteristics and Phanerozoic ore-forming processes.