The Paleo-Mesoproterozoic Lesser Himalayan Crystalline Sequence (LHCS) of the Himalayan orogen is critical in the understanding of pre-Himalayan tectonics in relation to the supercontinent Columbia. The LHCS is considered as the Paleoproterozoic northern boundary of the Indian Continental Block (ICB). Geological and geochemical studies of the LHCS have provided contrasting interpretations for its tectonic evolution, leading to a lack of consensus. This contribution reviews all the existing hypotheses for the Columbia assembly focusing on the nature of the northern margin of the ICB and address the inconsistencies regarding tectonic evolution of the LHCS. Petrological, geochemical, and geochronological observations of the LHCS from NW, Central and Eastern segments of the Himalaya suggest that the rocks witnessed a tectonic cycle of Paleoproterozoic oceanic subduction, rifting, and syn-collisional events, which is similar to the tectonic cycle experienced by the Paleoproterozoic rocks of the Eastern Cathaysia Block of South China. Integrating the signatures of these two domains yields a divergent double sided subduction tectonic scenario for their tectonic evolution. This work identified a three-stage tectonic evolution along the Eastern Cathaysia Block and northern boundary of ICB: First stage- Neoarchean oceanic subduction and arc magmatism beneath the Eastern Cathaysia Block; Second stage: c. 1950 Ma divergent double subduction, corresponding to slab-rollback/break off of the oceanic crust and asthenospheric upwelling beneath the Eastern Cathaysia Block, with synchronous subduction of the oceanic plate and formation of the LHCS magmatic belt along the ICB; Third stage: c. 1900 ̶ 1800 Ma soft collision between both domains, forming syn-collisional granites, which is synchronous with back-arc rifting and formation of anorogenic granites in both domains.

喜马拉雅造山带的古中元古代小喜马拉雅结晶序列（LHCS）对于理解与哥伦比亚超大陆相关的前喜马拉雅构造至关重要。LHCS被认为是印度大陆块（ICB）的古元古代北部边界。LHC的地质和地球化学研究为其构造演化提供了不同的解释，导致缺乏共识。该贡献回顾了哥伦比亚议会的所有现有假设，重点关注 ICB 北缘的性质，并解决了 LHCS 构造演化的不一致问题。来自喜马拉雅西北段、中段和东段的 LHC 岩石学、地球化学和地质年代学观测表明，这些岩石经历了古元古代海洋俯冲、裂谷和同步——碰撞事件，与华南东华夏地块古元古代岩石经历的构造旋回相似。综合这两个领域的特征，为它们的构造演化产生了一个不同的双面俯冲构造情景。这项工作确定了沿东华夏地块和 ICB 北部边界的三个阶段的构造演化：第一阶段 - 新太古代海洋俯冲和弧形岩浆作用东华夏区块下方；第二阶段：C。1950 Ma发散双俯冲，对应于东华夏地块下大洋地壳板片回滚/折断和软流圈上涌，大洋板块同步俯冲，沿ICB形成LHC岩浆带；第三阶段：C。1900～1800 Ma，两域软碰撞，形成同碰撞花岗岩，与两域的弧后裂陷和造山花岗岩的形成同步。