The Caroline Islands are located in a broad zone near plate boundaries in southwestern Pacific. Accumulating evidence suggests that the hotspot origin alone cannot completely explain the formation of the Caroline Islands. To investigate the tectonic setting of their formation, we calculated the effective elastic thickness (T_e) of the lithosphere beneath the Caroline Islands from an analysis of bathymetry and free-air gravity anomaly data by the admittance method. A synthetic model based on the actual bathymetry data of the Caroline Islands was developed for the finite window size biasing correction. The results show that the T_e values of the Caroline Islands (4.5–11.5 km) are significantly lower than the T_e expected for a normal oceanic lithosphere (23–50 km), and that the T_e values can be approximated by the depth to the 150 ± 100°C isotherm. The low T_e values indicate that the strength of the lithosphere beneath the Caroline Islands has been weakened by geological process. The thermal anomalies related to the Ontong Java Plateau and the South Pacific Isotopic and Thermal Anomaly, and the lithospheric fractures induced by interaction of plates are probable causes of the lithospheric strength reduction of the Caroline Islands.

卡罗琳群岛位于西南太平洋板块边界附近的广阔区域。越来越多的证据表明，仅靠热点起源无法完全解释卡罗琳群岛的形成。为了研究其形成的构造环境，我们通过利用导纳法对水深和自由重力异常数据进行了分析，计算了卡罗琳群岛下方岩石圈的有效弹性厚度（T _e）。建立了基于卡罗琳群岛实际测深数据的综合模型，用于有限的窗口尺寸偏差校正。结果表明，卡罗琳群岛（4.5-11.5 km）的T _e值明显低于T _e可以预期在正常的海洋岩石圈（23-50 km）中，并且T _e值可以近似于150±100°C等温线的深度。T _e值低表明，加洛林群岛下方的岩石圈强度已被地质过程削弱。与Ontong Java高原和南太平洋同位素和热异常有关的热异常以及由板块相互作用引起的岩石圈破裂可能是加洛林群岛岩石圈强度降低的原因。