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 (

The identification of oceanic-crust-derived melts is critical to improving our understanding of oceanic lithosphere subduction in various geodynamic settings. However, low-pressure melts derived from the oceanic crust can be misidentified because their compositions are often indistinguishable from those of typical arc-related rocks. In this study, we report geochronological and geochemical data for the Amdo volcanic rocks in the central Tibetan Plateau. Zircon U-Pb dating indicates that they were generated in the Early Jurassic (ca. 181 Ma), simultaneous with spatially associated MORB-like rocks of the Amdo ophiolite. The Amdo volcanic rocks are characterized by high SiO 2 and Na 2 O concentrations, low MgO, K 2 O, and Fe 2 O 3 T concentrations, and low Mg# values. They are enriched in light rare earth and large-ion lithophile elements, display negative Eu, Nb, and Ta anomalies, and yield low Sr (<360 ppm) and high Y (up to 57.6 ppm) concentrations with low Sr/Y ratios (<15.4). Whole-rock Sr-Nd and zircon Hf isotopic compositions (( 87 Sr/ 86 Sr) i = 0.7040-0.7058, ε Nd (t) = +3.9to +6.8, and zircon ε Hf (t) = +13.9 to +17.9) are different from those of regional continental-crust-derived granitoids but similar to those of contemporary MORBlike rocks that occur in regional ophiolites. Furthermore, zircon from the Amdo volcanic rocks yields U/Yb ratios similar to those of oceanic zircon. These characteristics, combined with regional geological observations, indicate that the Amdo volcanic rocks are a component of the Amdo ophiolite mélange and represent low-pressure partial melts of oceanic crust, generated during incipient northward subduction of the Bangong-Nujiang oceanic lithosphere beneath the Qiangtang terrane. Our study helps to constrain the history of the Bangong-Nujiang Ocean and provides a case study on the low-pressure melting of oceanic crust.

Front-fed parabolic reflectors are among the most commonly used antennas in the industry. While in spaceborne applications, membrane reflectors are very promising due to their lightweight and foldable features. However, considering the large size, small thickness and low stiffness, solar radiation and microwave radiation will have considerable influences on the antennas' shape accuracy as well as the radiation characteristics. In this article, a theoretical approach is presented to solve the multi-physical effects of the parabolic antenna. The deformation of the reflector is derived by the shallow shell theory, taking into account the solar pressure, the microwave pressure and the thermal effects due to solar and microwave heating. The far-field electromagnetic radiation pattern is then obtained by considering the deformation of the reflector. On the other hand, a numerical approach combining the finite element method, the multi-level fast multipole method, and the large element physical optics is also presented. Numerical examples suggest good agreement between the theoretical and numerical results. The methods have been applied into the analysis of design models in the Space Solar Power Station project. Also, these approaches can be directly extended into other space membrane reflector antennas.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.