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首页> 外文期刊>Journal of Asian earth sciences >Dolerites of the Woodlark Basin (Papuan Peninsula, New Guinea): A geochemical record of the influence of a neighbouring subduction zone
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Dolerites of the Woodlark Basin (Papuan Peninsula, New Guinea): A geochemical record of the influence of a neighbouring subduction zone

机译：伍德拉克盆地（新几内亚巴布亚半岛）的白云岩：邻近俯冲带影响的地球化学记录

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摘要

The Moresby Seamount located in the Woodlark Basin is a fragment of oceanic crust (dolerites and gabbros) generated 66.4 ±1.5 My ago before being obducted during the Eocene on the Australian margin. Since 8 My, the motion of a normal fault related to the opening of the Woodlark Basin is responsible for the unroofing of the Moresby seamount. The latter was sampled during the ODP campaign Leg 180 in 1998. Geochemical compositions of dolerites can be explained by a process of fractional crystallization in which the magnesian spinel was involved. Therefore fractionation processes took place at relatively high pressure (>1 GPa), most likely during the upward migration of deep magmas throughout the mantle. The Fe-rich gabbros, more differentiated than the dolerites, could have derived from an early differentiated magma evolving in the crust at relatively low pressures. The trace element content of dolerites indicates that their source was a depleted oceanic mantle slightly influenced by arc-related magmas. This study suggests that the ophiolites fragment of the Moresby seamount was created in the vicinity of a subduction zone; this model being in agreement with the regional tectonic setting of SE Asian since the Cainozoic.
机译：位于伍德拉克盆地的莫尔兹比海山是一部分洋壳（白云母和辉长岩），产生于66.4±1.5我年前，在澳大利亚边缘的始新世期间被捕捞。自8 My以来，与伍德拉克盆地开放有关的正常断层运动导致了莫尔斯比海山的顶棚。后者是在1998年ODP行动Leg 180期间取样的。白云石的地球化学成分可以通过分步结晶的过程来解释，其中涉及到镁尖晶石。因此，分馏过程是在相对较高的压力（> 1 GPa）下发生的，很可能是在深部岩浆向上整个地幔向上迁移的过程中发生的。富含铁的辉长岩，​​比白云石更具差异性，可能源于在相对较低的压力下在地壳中演化的早期分化岩浆。白云石的痕量元素含量表明，它们的来源是一块受弧相关岩浆轻微影响的贫化海洋地幔。这项研究表明，莫尔斯比海山的蛇绿岩碎片是在俯冲带附近形成的。该模型与自新生代以来东南亚的区域构造环境相吻合。

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