华南新元古代多地体汇聚-拼贴与资源效应【华南古大陆演化及其资源效应专辑】
- 收稿日期:
2024-02-04
- 网络出版日期:
2024-09-02
摘要: 新元古代是华南板块演化过程中的重要阶段,该时期的岩石记录了丰富的地壳增生-再造-重塑信息,并奠定了华南板块的物质基础。深入研究华南板块新元古代的地壳演化历史对理解华南板块的资源环境效应、全球新元古代超大陆聚合离散以及后续的生命大爆发等重大事件具有重要的意义。本文梳理了华南板块新元古代早-中期的重要地质记录,指出华南板块及其周边地区在新元古代可能长期存在海-陆格局和多个地体(或微陆块),而地体边界可由一系列的主动和被动大陆边缘岩石单元约束。华南板块在新元古代时期表现出来的与汇聚造山有关的俯冲带物质循环、岩浆-变质记录、增生杂岩、构造变形等关键证据共同表明,华南板块在新元古代早-中期可能存在长期的增生型造山作用和与之相关的多地体向扬子陆块的汇聚-拼贴过程。该增生造山和多地体汇聚过程较早以扬子北部为汇聚核心,随后由于地体拼贴主动大陆边缘逐步向外迁移而扩张,大陆不断增生,最终造就了现今华南板块的大体格局。同时,地体汇聚边界成为显生宙壳幔相互作用和地壳改造-分异的重要地区,很可能在显生宙的成矿过程中发挥了重要作用,这为研究基底组成特征与显生宙成矿作用之间的联系提供了一个新思路。
Neoproterozoic multi-terrane convergence in South China and its resource implications
- Received Date:
2024-02-04
- Available Online:
2024-09-02
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.