The formation and evolution of arc-backarc systems govern crustal production in some of the most volcanically and hydrothermally active environments on Earth. This study presents the first complete three-dimensional density model of the active arc-backarc system in the southwest Pacific comprising the Lau Basin and Tofua arc. Seafloor density and crustal thickness maps reveal changes in crustal composition and growth rates throughout the basin and along the volcanic arc. Crustal thickness varies significantly between the different centers of accretion (i.e., assemblages), resulting from seafloor spreading and subsurface melt accumulation below volcanic fields. Volumetric growth rates were calculated for each assemblage, corresponding to their respective contribution to basin expansion. The highest crustal density and growth rates are thought to be related to a mantle-derived melt source entering the basin from the north around the edge of the subducting Pacific Plate. This study shows that the inverse modeling approach can be applied to global gravity data sets to characterize and quantify the density and thickness of the crust anywhere in the oceans.

中文翻译：

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量化弧背弧系统中的地壳生长：Lau 盆地的重力反演建模


弧-背弧系统的形成和演化控制着地球上一些火山和热液最活跃的环境中的地壳生产。本研究提出了西南太平洋主动弧-背弧系统的第一个完整三维密度模型，包括 Lau Basin 和 Tofua 弧。海底密度和地壳厚度图揭示了整个盆地和火山弧沿线的地壳组成和增长率的变化。地壳厚度在不同的吸积中心（即组合）之间差异很大，这是由海底扩张和火山场下方地下熔融堆积造成的。计算每个组合的体积增长率，对应于它们各自对流域扩张的贡献。最高的地壳密度和增长率被认为与地幔衍生的熔源从俯冲太平洋板块边缘的北部进入盆地有关。这项研究表明，逆向建模方法可以应用于全球重力数据集，以表征和量化海洋中任何地方的地壳密度和厚度。