How Pre‐Existing Strength Heterogeneities and Differential Extension Shaped Rift Initiation and Propagation in the South China Sea: An Analog Perspective.

Λεπτομέρειες βιβλιογραφικής εγγραφής
Τίτλος:	How Pre‐Existing Strength Heterogeneities and Differential Extension Shaped Rift Initiation and Propagation in the South China Sea: An Analog Perspective.
Συγγραφείς:	Yang, Gengxiong^1,2,3 (AUTHOR) yanggx@smail.nju.edu.cn, Rosenau, Matthias⁴ (AUTHOR), Yin, Hongwei³ (AUTHOR), Pan, Shuxin⁵ (AUTHOR), Pei, Yangwen^1,2 (AUTHOR)
Πηγή:	Journal of Geophysical Research. Solid Earth. Jul2026, Vol. 131 Issue 7, p1-22. 22p.
Θεματικοί όροι:	Rifts (Geology), Neotectonics, Structural geology, Strains & stresses (Mechanics)
Γεωγραφικοί όροι:	South China Sea
Περίληψη:	Continental rifting rarely occurs synchronously along strike and with uniform width. Instead, it commonly involves diachronous, progressive opening and rift propagation resulting in V‐shaped rifts. Rotational, scissor‐like opening is a common model explaining V‐shaped rifts near plate tectonic rotational poles with steep extension gradients along‐strike. However, the mechanisms driving V‐shaped rifts located far from such poles, such as the South‐China Sea (SCS), remain less well understood. Here, we use crustal‐scale analog modeling to investigate the processes and mechanisms of V‐shaped rift formation in regions distant from rotational poles, taking the SCS as a prototype. Our results demonstrate that the V‐shaped opening of basins can be governed by the combined effects of differential extension and inherited strength heterogeneities in the lithosphere. Applied to the SCS, our models indicate that along‐strike variations in Proto‐SCS subduction drove spatially variable extension, producing east‐to‐west diachronous rift initiation and contrasting crustal‐thinning patterns between the eastern and western segments. In addition, weak remnants of Mesozoic magmatic arcs in the eastern segment and strong, pre‐existing continental basement blocks in the western segment acted as key structural‐rheologic controls on strain localization, shaping the geometry of the basin and regulating the degree of necking along the continent–ocean boundary. Collectively, these processes produced the east‐ward younging and narrowing V‐shaped rift represented by the SCS today. These findings provide new insights into the debated origin of the SCS in particular and broadens our understanding of rift propagation in settings distant from rotational poles in general. Plain Language Summary: The South China Sea (SCS) is characterized by westward‐propagating rifting and seafloor spreading, which produced a distinctive V‐shaped oceanic basin. Because this geometry developed far from the relevant Euler poles, it cannot be readily explained by a simple rotational opening model. Instead, the progressive opening of the SCS likely reflects the combined effects of Cenozoic tectonic forcing and Mesozoic inherited lithospheric structures. Using analog modeling, we explored multiple factors that may have governed the V‐shaped configuration of the SCS: (a) variations in extension rate from east to west, driven by unequal subduction of the Proto‐SCS, and (b) inherited geological features, including remnant Mesozoic magmatic arcs in the east and continental basement blocks in the west. The results indicate that higher extension rates in the east led to earlier deformation and localized strain along a weak zone related to a remnant magmatic arc, producing a wide and deep rift. In contrast, strain in the west was focused between pre‐existing continental basement blocks, generating narrow and deep rift zones. All these processes combined produced an east‐wide, west‐narrow V‐shaped rift. These findings provide new insights into the geological interactions that shaped the SCS and other V‐shaped rifts far from rotation poles. Key Points: V‐shaped rift formed before spreading, controlled by differential extension and crustal strength heterogeneitiesDifferential extension governed rift timing and propagation, while inherited strength heterogeneities controlled the location and geometryContinental basement blocks localized rifts, and also generated troughs and oblique shear faults [ABSTRACT FROM AUTHOR]
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