Western Northern Luzon Isotopic Evidence of Transition From Proto‐South China Sea to South China Sea Fossil Ridge Subduction
Western Northern Luzon Isotopic Evidence of Transition From Proto‐South China Sea to South China Sea Fossil Ridge Subduction
复制标题
吕宋岛北方西部从原南海向南海化石脊俯冲转变的同位素证据
DOI：
10.1029/2019tc005639
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发表时间：
2020-01
期刊：
影响因子：
4.2
通讯作者：
Hai‐Quan Liu;G. Yumul;C. Dimalanta;K. Queaño;X. Xia;Touping Peng;Jiangbo Lan;Yigang Xu;Yi Yan;J. Guotana;Valerie Shayne V. Olfindo
中科院分区：
文献类型：
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作者：
Hai‐Quan Liu;G. Yumul;C. Dimalanta;K. Queaño;X. Xia;Touping Peng;Jiangbo Lan;Yigang Xu;Yi Yan;J. Guotana;Valerie Shayne V. Olfindo
对吕宋岛北方西部典型岩浆活动进行了时间地球化学对比，以重建新生代构造。吕宋岛北方西部的渐新世-更新世岩浆显示出与洋内弧岩浆作用相似的元素和Sr-Nd-Hf-Pb-O同位素地球化学特征，与地幔楔的起源一致，并伴有分离结晶。具体而言，渐新世-中新世（~26.8-15.6 Ma）中央科迪勒拉dibrillera杂岩样品表现出Sr-Nd同位素之间的负相关性，与远洋沉积物释放的流体/熔体的地幔交代作用一致。中更新世样品（~9 Ma）岩浆活动显示出洋内弧同位素特征，表明俯冲远洋沉积物的化学印记。中更新世（<~9 Ma）熔岩显示出富集的地幔型同位素组成，与地幔中陆源沉积物的输入一致。台湾-吕宋岛岩浆活动的Sr-Nd-Hf-Pb同位素的时间变化，结合古地磁证据，反映了从原南海到南海化石脊俯冲到北方吕宋岛西部的过渡。此外，本研究还强调了在弧-陆碰撞体系中，下板块相对富集的组分在上覆幼年洋壳成熟过程中的重要性。
Temporal geochemical comparisons are conducted for representative magmatism from western Northern Luzon to reconstruct the Cenozoic tectonics. Oligo‐Pleistocene magmas from western Northern Luzon display elemental and Sr‐Nd‐Hf‐Pb‐O isotope geochemistry similar to intraoceanic arc magmatism, consistent with derivation from the mantle wedge, coupled with fractional crystallization. Specifically, the Oligo‐Miocene (~26.8–15.6 Ma) Central Cordillera diorite complex samples exhibit a negative correlation between Sr‐Nd isotopes, consistent with mantle metasomatism by fluids/melts released from pelagic sediments. The Mio‐Pleistocene samples (~9 Ma) magmatism exhibit intraoceanic arc isotopic signatures, suggestive of a chemical imprint from subducted pelagic sediments. The Mio‐Pleistocene (<~9 Ma) lavas display enriched mantle‐type isotope compositions, consistent with an input of terrigenous sediment in the mantle. The temporal variations in Sr‐Nd‐Hf‐Pb isotopes for the Taiwan‐Luzon magmatism, combined with paleomagnetic evidence, mirror a transition from the Proto‐South China Sea to the South China Sea fossil ridge subduction beneath western Northern Luzon at ~9 Ma. In addition, this study also highlights the importance of relatively enriched components in the lower plate in the maturation of overriding juvenile oceanic crust in an arc‐continent collision system.