Mode and timing of terrane accretion in the forearc of the Andes in Ecuador
Mode and timing of terrane accretion in the forearc of the Andes in Ecuador
复制标题
厄瓜多尔安第斯山脉弧前地体增生的模式和时间
DOI：
--
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
F. Bussy
中科院分区：
文献类型：
--
作者：
C. Vallejo;W. Winkler;R. Spikings;Léonard Luzieux;F. Heller;F. Bussy
厄瓜多尔西科迪勒拉山脉（Pallatanga组和圣胡安单元）的火山基底由镁铁岩和超镁铁岩组成，曾经形成海洋高原。这些岩石的放射性年龄与厄瓜多尔沿海Pinon组洋坪基底岩石的角闪石40 Ar/ 39 Ar坪年龄（88 ± 1.6 Ma）重叠，加勒比海和哥伦比亚西部海洋高原层序的年龄为92-88 Ma。这些结果表明，西科迪勒拉和平坦的前弧在厄瓜多尔的海洋高原岩石来自晚白垩世加勒比-哥伦比亚海洋高原。洋内岛弧序列（里约卡拉组）覆盖在西科迪勒拉高原和产量结晶年龄范围约。85和72马。地球化学和放射性年龄的岛弧熔岩从里约卡拉集团，结合年龄范围和地球化学的浊流，火山岩产品，表明弧开始向西俯冲下加勒比海高原。它们与厄瓜多尔沿海的岛弧岩石（Las Orquideas、圣洛伦索和Cayo组）和哥伦比亚（Ricaurte弧）同时代。这些岛弧
The volcanic basement of the Ecuadorian Western Cordillera (Pallatanga Formation and San Juan unit) is made up of mafi c and ultramafi c rocks that once formed an oceanic plateau. Radiometric ages from these rocks overlap with a hornblende 40 Ar/ 39 Ar plateau age of 88 ± 1.6 Ma age obtained for oceanic plateau basement rocks of the Pinon Formation in coastal Ecuador, and with ca. 92–88 Ma ages reported for oceanic plateau sequences in the Caribbean and western Colombia. These results suggest that the oceanic plateau rocks of the Western Cordillera and fl at forearc in Ecuador are derived from the Late Cretaceous Caribbean-Colombia oceanic plateau. Intraoceanic island-arc sequences (Rio Cala Group) overlie the plateau in the Western Cordillera and yield crystallization ages that range between ca. 85 and 72 Ma. The geochemistry and radiometric ages of island-arc lavas from the Rio Cala Group, combined with the age range and geochemistry of their turbiditic, volcaniclastic products, indicate that the arc was initiated by westward subduction beneath the Caribbean Plateau. They are coeval with island-arc rocks of coastal Ecuador (Las Orquideas, San Lorenzo, and Cayo Formations) and Colombia (Ricaurte Arc). These island-arc