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首页> 外文期刊>Earth and Planetary Science Letters: A Letter Journal Devoted to the Development in Time of the Earth and Planetary System >Evidence for Early Cretaceous oceanic crust trapped in the Philippine Sea Plate
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Evidence for Early Cretaceous oceanic crust trapped in the Philippine Sea Plate

机译：菲律宾海床中捕获的早白垩世洋壳的证据

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摘要

The Huatung Basin is a small oceanic basin located east of Taiwan. Previous age estimates from magnetic lineation studies indicated an Eocene age for the basin, and formation from the Central Basin Spreading Center of the West Philippine Basin during the last phase of spreading in Middle Eocene. New Ar/Ar ages obtained on gabbros dredged on oceanic basement highs of the Huatung Basin are Early Cretaceous. These old ages are consistent with Early Cretaceous ages determined on radiolarian assemblages from Lanyu Island (Luzon-Arc). We have performed magnetic anomalies modeling for an Early Cretaceous oceanic crust. Our results are in good agreement with new Ar/Ar ages determination. The best fit is indeed obtained with an opening of the Huatung Basin during the Early Cretaceous from 131 to 119 Ma, with a half spreading rate varying between 25 and 30 mm/yr. The spreading center appears to be located south of the actual basin. The abnormal depth (5500 m instead of 5900 m) and thickness (～12 km instead of 6 km) of the crust beneath the basin indicate that there was probably an excess supply of magma during its formation. We propose that the basin is a fragment of the former 'proto-south China Sea' or possibly the 'New Guinea Basin' that has been trapped by the Philippine Sea Plate.
机译：华东盆地是台湾东部的一个小洋盆。磁线研究的先前年龄估计表明该盆地是始新世时代，并且在中始新世扩展的最后阶段是西菲律宾盆地中央盆地扩展中心的形成。在华东盆地洋基高处疏g的辉长岩上获得的新的Ar / Ar年龄是早白垩世。这些年龄与从兰屿（Luzon-Arc）的放射虫组合确定的早白垩纪年龄一致。我们已经对白垩纪早期的洋壳进行了磁异常建模。我们的结果与新的Ar / Ar年龄测定非常吻合。实际上，白垩纪初期华东盆地在131 Ma至119 Ma范围内开放，并获得了最佳拟合，半张开速率在25至30 mm / yr之间变化。传播中心似乎位于实际盆地的南部。盆地下方地壳的异常深度（5500 m而不是5900 m）和厚度（〜12 km而不是6 km）表明岩浆形成期间可能存在过多的岩浆供应。我们认为该盆地是菲律宾海床所困的前“南中国原始海”或可能的“新几内亚盆地”的一部分。

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