卡罗琳板块及其附近地区的岩石圈有效弹性厚度

本文利用卡罗琳板块及其附近地区的自由空气重力异常和海水深度数据,结合滑动窗口导纳技术(MWAT),计算了该地区的岩石圈有效弹性厚度T_e.本文使用Multitaper(多窗谱)方法对功率谱密度进行估计,基于实际的海底地形,通过模拟计算得到了MWAT方法较真值的改正,MWAT方法计算的结果偏小20%左右.研究结果显示卡罗琳板块及其附近地区的T_e变化范围为1~34km.研究区域包括了海山、海底高原、俯冲带、扩张洋脊等多种构造,对它们的岩石圈强度的研究为认识西太平洋地区岩石圈的构造和演化提供了重要的依据.T_e与加载时的岩石圈年龄、地表热流相关.T_e与海底地壳年龄之间的关系显示T_e主要位于板块冷却模型的450℃的等温线深度以上.西太平洋的Magellan海山和Marcus-Wake Guyots(MWG)地区的T_e主要分布在加载形成时板块冷却模型的200℃的等温线深度附近,较低的等温线可能受太平洋超级地幔柱的影响.我们的研究结果也显示在研究区域内海洋地壳的热流与T_e之间存在一定的反相关性.

The effective elastic thickness of the Caroline plate and its adjacent areas

The purpose of this work is to study the effective elastic thickness (T_e) of the Caroline plate and its adjacent areas by using free-air gravity anomaly and bathymetric data, in combination with a moving window admittance technique (MWAT). We use the multitaper spectral estimation method to calculate the power spectral density. Correction is obtained through synthetic tests with actual bathymetric data. Results show that the recovered T_e is about 20% lower than the input T_e. The Caroline plate and adjacent areas have a T_e range of 1~34 km. The study area includes a wide range of features such as seamounts, plateaux, subduction zones and spreading ridges. The examination of the lithospheric strength for these structures provides important information for the tectonic setting and evolution of the Western Pacific lithosphere. T_e is related to the age of the lithosphere at the time of loading, heat flow and other proxy features. Plots of T_e versus ages of the oceanic crust show that T_e is above the depth of 450℃ isotherm based on a cooling plate model. For the Magellan seamounts and Marcus-Wake Guyots (MWG) areas, plots of T_e versus the ages of the lithosphere at the time of loading suggest that T_e is at around the depth of 200℃ isotherm based on a cooling plate model. The low isotherm could resulted from the effect of the South Pacific supper plume. Our results also show a negative correlation between heat flow and T_e in the study area.