关键词: 造山带, 洋岛（海山）, 古洋盆, 热点（地幔柱）, 洋中脊, 洋内弧, 班公湖—怒江缝合带, 中特提斯

Abstract:  The accurate reconstruction of the formation and evolution of ancient ocean basins, as represented in the orogenic belts, constitutes an important research content in geotectonics. Focusing on the Meso-Tethys (Bangong-Nujiang suture zone) of northern Tibet, this study systematically examines the characteristics of ocean islands (seamounts) and therir geological significance in understanding paleo-oceanic basin dynamics. Ocean islands (seamounts) within orogenic belts exhibit not only widespread distribution but also remarkable diversity.In addition to the traditional hotspot-type ocean islands (seamounts), they also include slow- and fast-spreading mid-ocean ridge-type ocean islands (seamounts) and intra-oceanic arc-type ocean islands (seamounts). Their common characteristics are the development of ultrabasic-basic magmatic rock assemblages and pelagic colluvial conglomerates. Ocean islands (seamounts) are the main components of “oceanic crust fragments” in orogenic belts and serve as important carriers of information on the formation and evolution of ancient ocean basins. Particularly, they provide critical insights, particularly in revealing the nature of ancient ocean basins, reconstructing their convergence and termination processes, and analyzing the temporal duration of ancient oceanic crust. 

Key words: orogenic belt, ocean island (seamount), ancient ocean basin, hotspot (mantle plume), mid-ocean ridge, intra-oceanic arc, Bangong-Nujiang suture zone, Meso-Tethys