Abstract A thick Infra-Cambrian to Phanerozoic sedimentary sequence in eastern Arabia conceals a poorly known Neoproterozoic basement that once separated the currently exposed Arabian Shield (western Arabia) from NW India in Gondwana. In this study, the Arabian Platform (eastern Arabia) is targeted by relatively high-resolution passive-source seismic tomography for the first time, which aims to illuminate crust and upper mantle structure in order to make inferences on their nature and origin. This is facilitated by a new broadband seismic network of 55 stations in the United Arab Emirates (UAE), which has recorded sufficient teleseismic body wave data to allow for the determination of three-dimensional seismic structure. Using a grid-based eikonal solver and a subspace inversion technique implemented in FMTOMO, relative arrival-time residuals from teleseismic earthquakes are mapped as 3-D P-wave velocity perturbations in the upper mantle beneath the seismic network. The resultant tomographic images reveal a marked transition from higher velocities in the Gulf of Oman to lower velocities in the west that we interpret to indicate the lithospheric boundary between Cretaceous Tethyan oceanic lithosphere and the Arabian passive continental margin. The northern extent of Tethyan oceanic lithosphere appears to terminate against a possible offshore continuation of the Dibba fault, until now only identified onshore. Further inland, the tomographic model exhibits a number of low- and high- velocity anomalies with a predominant NW orientation. Significantly, one well-defined high velocity anomaly is situated along strike of the Neoproterozoic exposure of volcanic-arc granodiorites found in northern Oman. We relate this anomaly to an intra-oceanic arc created during the Tonian subduction of the Mozambique Ocean, which strongly support the idea of continental growth in the Arabian Platform via magmatic arc accretion.

中文翻译：

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从远震体波断层扫描看阿拉伯地台东北部上地幔结构

摘要 阿拉伯东部厚厚的下寒武纪至显生宙沉积层序隐藏了一个鲜为人知的新元古代基底，该基底曾经将目前暴露的阿拉伯地盾（阿拉伯西部）与冈瓦纳的印度西北部隔开。本研究首次以相对高分辨率的被动源地震层析成像为目标，对阿拉伯地台（阿拉伯东部）进行了成像，旨在阐明地壳和上地幔结构，以推断其性质和起源。阿拉伯联合酋长国 (UAE) 的 55 个台站的新宽带地震网络促进了这一点，该网络记录了足够的远震体波数据，可以确定三维地震结构。使用基于网格的 eikonal 求解器和在 FMTOMO 中实现的子空间反演技术，远震地震的相对到达时间残差被映射为地震网络下方上地幔中的 3-D P 波速度扰动。由此产生的断层图像揭示了从阿曼湾的较高速度到西部较低速度的显着转变，我们将其解释为表明白垩纪特提斯大洋岩石圈和阿拉伯被动大陆边缘之间的岩石圈边界。特提斯大洋岩石圈的北部似乎终止于 Dibba 断层可能的离岸延续，直到现在仅在陆上确定。在内陆更远的地方，断层扫描模型显示出许多以 NW 为主的低速和高速异常。显着地，在阿曼北部发现的火山弧花岗闪长岩的新元古代出露的走向上有一个明确定义的高速异常。我们将此异常与莫桑比克海洋托尼安俯冲期间产生的洋内弧联系起来，这强烈支持通过岩浆弧吸积在阿拉伯地台上大陆生长的想法。