Heterogeneous Age-Averaged Crustal Thickness in the Southeast Indian Ocean

Age-averaged crustal thickness (AACT) along the SEIR spreading path from 74°E to 127°E, focusing on oceanic crust younger than 30 Ma. The AACT represents the mean crustal thickness measured along flow lines, which correspond to seafloor spreading trajectories across the oceanic basin. Since each flow line intersects oceanic crust that progressively ages with increasing distance from the MOR, the AACT is fundamentally independent of crustal age. A series of seafloor spreading/flow paths, with a 2 km interval, are derived from the plate reconstruction model (Seton et al., 2020), which is based on oceanic crustal age contours, fracture zones, and other parameters. The AACT can then be estimated by integrating the crustal thickness along each flow line. And thus, the variations of the AACT along the SEIR can be derived.

沿东南印度洋洋中脊（Southeast Indian Ridge, SEIR）扩张路径，从74°E至127°E范围内的年龄平均地壳厚度（Age-averaged Crustal Thickness, AACT）数据集，其研究对象为年龄小于30 Ma的洋壳。该年龄平均地壳厚度（AACT）指沿流线（flow lines）测得的平均地壳厚度，流线对应跨洋盆的海底扩张轨迹。由于每条流线均与距洋中脊（Mid-Ocean Ridge, MOR）距离越远、年龄越老的洋壳相交，因此AACT本质上与地壳年龄无关。本数据集基于板块重建模型（Seton等，2020）构建，该模型以洋壳年龄等值线、断裂带及其他参数为依据，从中提取了间隔为2 km的一系列海底扩张/流线路径。随后可通过沿每条流线积分地壳厚度来估算AACT，由此可得到东南印度洋洋中脊沿线AACT的变化特征。