Geophysical study of the Solomon islands plate convergence

所罗门岛弧区是一个复杂的板块汇聚带。北方是北所罗门海沟，太平洋板块与翁东爪哇高原似乎在与弧系碰撞。另一个在南边的海沟是圣克里斯托瓦尔海沟，印度-澳大利亚板块和所罗门海板块目前正俯冲到所罗门弧之下。我们使用配备130道多道地震反射测量系统和140道地震反射测量系统的R/V Maurice Ewing在所罗门海地区进行了日美联合地球物理调查。1995年10月17日至11月19日期间，日本方面带来了18个数字小型海底地震仪（OBS），它们被放置在整个弧形系统的464公里长的断面上。气枪射击长达4 000多公里，覆盖整个所罗门群岛地区。因此，我们成功地获取了数据，获得了整个地壳结构并测试了翁东爪哇高原的不同碰撞模型。对数据的初步研究表明，翁通爪哇高原的俯冲似乎正在进行中，尽管一般认为目前的俯冲只来自南侧。此外，更有可能的是，高原大部分是俯冲，而不是向上楔入弧。这表明，海洋高原的命运是这样的，它主要是再循环到地幔，并没有显着的贡献，以增加大陆体积。

The Solomon island arc area is a complex plate convergence Zone. On the northern side is the North Solomon Trench at which the Pacific plate with the Ontong Java plataeau seems to be in collision with the arc system. Another trench on the southern side is the San Cristobal Trench, where the Indo-Australian plate and the Solomon Sea plate are presently subducting beneath the Solomon arc.We have carried out a Japan-U.S.joint geophysical survey in the Solomon Sea region using the R/V Maurice Ewing equipped with a 130-ch multi-channel seismic reflection survey system and a 140-liter airgun array during the period of October 17 to November 19,1995. The Japanese side brought 18 digital compact ocean bottom seismographs (OBS's) which were placed along a 464-km long transect of the whole arc system. Airgun shooting was made for more than 4,000 km long covering the whole Solomon Islands region. Thus, we have succeeded in acquiring data to obtain the whole crustal structure and to test different collision models of the Ontong Java plateau. Preliminary look into the data shows that the subduction of the Ontong Java plateau seems to be ongoing despite the general notion that the present subduction is only from the southern side. Also, it is more likely that the plateau is mostly subducting rather than wedging upward onto the arc. This suggests that the fate of an oceanic plateau is such that it is mostly recycled into the mantle and does not significantly contribute to the increase of continental volume.