| Autor: |
Liu, Hai‐Quan, Yumul, Graciano P., Dimalanta, Carla B., Queaño, Karlo, Xia, Xiao‐Ping, Peng, Tou‐Ping, Lan, Jiang‐Bo, Xu, Yi‐Gang, Yan, Yi, Guotana, Juan Miguel R., Olfindo, Valerie Shayne |
| Zdroj: |
Tectonics; Feb2020, Vol. 39 Issue 2, p1-21, 21p |
| Abstrakt: |
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) exhibit consistent 87Sr/86Sr ratios with variable εNd and partially overlap with those of Scarborough seamount basalts, consistent with mantle metasomatism by fluids/melts released from the Scarborough seamount basalts, which are being subducted beneath Northern Luzon with the South China Sea fossil ridge. Temporal changes in Sr‐Nd‐Hf‐Pb isotopes are also observed for the Taiwan‐Luzon arc magmatism. The Oligo‐Miocene (>~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. Key Points: Oligo‐Miocene Central Cordillera diorite complex exhibit Sr‐Nd isotope composition controlled by pelagic sedimentsMio‐Pleistocene igneous rocks exhibit Sr‐Nd isotope composition controlled by the subducted Scarborough Seamount Chain basaltsTemporal variations in isotope geochemistry for the Taiwan‐Luzon magmatism mirror a tectonic transition and crustal maturation [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Plný text