Early Cretaceous (∼138–134 Ma) Forearc Ophiolite and Tectonomagmatic Patterns in Central Tibet: Subduction Termination and Re‐initiation of Meso‐Tethys Ocean Caused by Collision of an Oceanic Plateau at the Continental Margin?

Abstract

Oceanic plateaus are an important part of the oceanic lithosphere and are more buoyant, thicker, and topographically higher than normal oceanic crust (Kerr, 2014). The arrival of an oceanic plateau at a trench can therefore lead either to "docking" at the trench or subduction at shallow or flat angles, depending on variables such as the buoyancy, crustal thickness, and age and size of the plateau, and the rate of convergence and rheology of the margin (Kerr, 2014; Spikings & Simpson, 2014; Vogt & Gerya, 2014). However, in either situation (docking vs. subducting), an oceanic plateau will perturb the normal subduction zone and inhibit the production of arc volcanism. Furthermore, if the plateau docks at the trench, a new subduction zone might initiate spontaneously owing to the physical differences between the plateau and normal crust or to the plate-force of collision (Kerr, 2014; Stern & Gerya, 2018). However, the role of oceanic plateaus in the evolution of ancient oceans has generally been ignored because the relevant geological records would inevitably have been destroyed by post-closure tectonic events. The subduction and subsequent closure of the Meso-Tethys Ocean (or Bangong-Nujiang Tethys Ocean), now represented by the Bangong-Nujiang Suture Zone (BNSZ) in central Tibet (Figure 1), followed by collision between the Lhasa and Qiangtang terranes, has played a vital role in the formation of the Tibetan Plateau before India-Asia collision (

Petrogenesis of Early Cretaceous volcanic rocks from the Rena-Co area in the southern Qiangtang Terrane, central Tibet: evidence from zircon U-Pb geochronology, petrochemistry and Sr-Nd-Pb–Hf isotope characteristics

“…2005, 2007), probably as a result of the collision of an oceanic plateau with the Qiangtang continental margin (Zeng et al . 2021). It has long been recognized that the BNOL subducted northwards beneath the southern QT before the closure of the BNO (e.g.…”

“…2016; Zeng et al . 2021). However, intense controversies remain on the closure of the BNO, and two main versions of the final closure of the BNO have been proposed.…”

“…This zone is generally considered the locus of the ancient Bangong-Nujiang Ocean (BNO) (Yin & Harrison, 2000;Kapp et al 2003Kapp et al , 2005Pan et al 2004;Guynn et al 2006;Zhang et al 2012;Li et al 2016;Zhu et al 2016). The closure of the BNO, followed by the subsequent collision between the Lhasa and Qiangtang terranes, significantly contributed to the initial growth of the Tibetan Plateau before the Indo-Asian collision (Kapp et al 2007;Shi et al 2008Shi et al , 2020Zhang et al 2012Zhang et al , 2014Zhu et al 2016;Zeng et al 2021). However, intense controversies remain on the closure of the BNO, and two main versions of the final closure of the BNO have been proposed.…”

Grain-scale zircon Hf isotope heterogeneity inherited from sediment-metasomatized mantle: Geochemical and Nd-Hf-Pb-O isotopic constraints on Early Cretaceous intrusions in central Lhasa Terrane, Tibetan Plateau

“…1a). The BNSZ represents the remnants of the Meso-Tethys Ocean, which was proposed to have closed in the Late Jurassic or the Early Cretaceous (Zeng et al, 2021a). The Meso-Tethys Ocean slab has subducted northwards beneath the Qiangtang Terrane since Early Jurassic (Li et al, 2014, but it remains a controversy whether this paleo-ocean slab has ever subducted towards south beneath the Lhasa Terrane (e.g., Zeng et al, 2018;Li et al, 2018).…”

New Middle Jurassic Paleomagnetic and Geochronologic Results From the Lhasa Terrane: Contributions to the Closure of the Meso‐Tethys Ocean and Jurassic True Polar Wander

“…With regard to these oceans, the Meso‐Tethys Ocean plays a crucial role in understanding the formation and evolution of the Tibetan Plateau prior to the India‐Asia collision, because its subduction, closure, and subsequent continental collision resulted in the initial uplift of the proto‐Tibetan Plateau, which influenced the drainage divide and atmospheric circulation (e.g., Ding et al., 2022; Lippert et al., 2014). However, the history of the Meso‐Tethys Ocean remains hotly debated, such as the estimated closure time of the Meso‐Tethys Ocean ranging from the Middle Jurassic (e.g., Ma, Hu, Kapp, BouDagher‐Fadel, & Lai, 2020; Ma, Hu, Kapp, Lai, et al., 2020; Sun et al., 2019), Late Jurassic to Early Cretaceous (e.g., Fan et al., 2021; Kapp & DeCelles, 2019; Ma et al., 2018; Zeng et al., 2021) to the Late Cretaceous (e.g., Li, Lu, et al., 2022; Yang et al., 2022). The Lhasa terrane is separated from the Qiangtang terrane to the north by the Bangong‐Nujiang suture zone which represents the Meso‐Tethys oceanic relict (e.g., Metcalfe, 2021).…”