Seismic Probing of the Ontong-Java Plateau: A Passcal Experiment

[218907] Okal本研究的目的是研究海底火成岩活动的最大表现——安通-爪哇高原的地震构造。由pascal仪器组成的四个地震台站将在密克罗尼西亚群岛的楚克、波纳佩、科斯雷和瑙鲁部署两年。所罗门俯冲带的震源将用于研究高原表面波的频散，以测量200公里深度的地震结构。同时，针对该地区地壳和上地幔的结构各向异性，将开展一系列体波实验。这项工作有望为以下问题提供答案：地壳的确切厚度、深部地壳的性质、高原地幔（盖层和下面的低速带）的结构，以及上地幔各向异性的程度和方向。这些参数将对白垩纪高原的侵位环境和机制产生制约作用。＊＊＊

9218907 Okal This research is to study the seismic structure of the Ontong- Java Plateau, the largest expression of igneous activity of the ocean floor. Four seismic stations composed of PASSCAL instruments will be deployed for two years on the Micronesian islands of Chuuk, Pohnpei, Kosrae and Nauru. Earthquake sources in the Solomon subduction zone will be used to investigate the dispersion of surface waves over the plateau to measure seismic structure to depths on the order of 200 km. Concurrently, a number of body-wave experiments will be conducted targeting the structural anisotropy of the crust and upper mantle in the area. The work is expected to provide answers to such questions as the exact thickness of the crust, the nature of the deep crust, the structure of the mantle (lid and underlying low-velocity zone) of the plateau, and the extent and direction of anisotropy in the upper mantle. In turn, these parameters will put constraints on the environment and mechanism of emplacement of the plateau in the Cretaceous. ***