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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 >Rift jump process in Northern Iceland since 10 Ma from ~(40)Ar/~(39)Ar geochronology
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Rift jump process in Northern Iceland since 10 Ma from ~(40)Ar/~(39)Ar geochronology

机译：〜（40）Ar /〜（39）Ar年代学以来10 Ma以来冰岛北部的裂谷跳跃过程

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摘要

Due to the westward American-Eurasian plate boundary migration, the rift zone location in Northern Iceland imposed by the stable Icelandic hotspot has jumped eastward. The present-day North Volcanic Zone of Iceland is thus shifted about 100 km to the east with respect to the Kolbeinsey Ridge. A Miocene paleo-rift location was proposed along the Hunafloi-Skagi axis. Unconformities inside the lava pile on both sides of the present-day rift as a result of the new rift formation have been used to date the rift jump, but timing is still controversial. Whether extinction of the paleo-rift was synchronous with initiation of the new rift or the two rifts were active during some time period is unknown. Using the ~(40)Ar/~(39)Ar radiochronology method, 37 dykes were dated along a 350 km profile parallel to the divergent plate motion direction (i.e., ESE-WNW) crossing the present rift, the unconformities, and the inferred paleo-rift. Our results reveal that the paleo-rift axis was not located along the Hunafloi-Skagi axis, but 60 km to the east. This previously unknown paleo-rift is named the Skagafjordur paleo-rift. It remained active until approximately 3 Ma. The activity of the present North Volcanic Zone started about 8-8.5 Ma, intruding 9-9.5 Myr rocks located at least 10 km east of the Skagafjordur paleo-rift axis. Consequently, the two rifts were simultaneously active for 5-5.5 Myr. During this time period, their accretion rates were nearly equal but with asymmetrical opening, the largest rates occurring on external flanks. These results are coherent in the Icelandic context and permit a first reconstruction of the evolution of Northern Iceland since 10 Ma.
机译：由于美国向欧亚板块边界的西移，冰岛北部稳定地区在冰岛北部造成的裂谷带位置向东跳。因此，如今的冰岛北部火山区相对于科尔本西岭向东移动了约100公里。提出了沿Hunafloi-Skagi轴的中新世古裂谷位置。由于新的裂谷形成，导致了当前裂谷两侧熔岩堆内部的不整合已被用于对裂谷跃迁进行了测年，但时间仍存在争议。尚不知道古裂谷的消亡与新裂谷的开始是同步的还是两次裂谷在某个时期是活跃的。使用〜（40）Ar /〜（39）Ar放射年代学方法，沿着平行于当前裂谷，不整合面和推论断层的板块运动方向（即，ESE-WNW）的350 km剖面测得了37个堤坝。古裂谷。我们的研究结果表明，古裂谷轴不在沿Hunafloi-Skagi轴，而是向东60公里。这种以前未知的古裂谷被称为Skagafjordur古裂谷。它一直活跃到大约3 Ma。目前的北火山带的活动始于约8-8.5 Ma，侵入了位于Skagafjordur古裂谷轴线以东至少10 km处的9-9.5 Myr岩石。因此，两次裂口同时激活5-5.5 Myr。在这段时间内，它们的增生率几乎相等，但开口不对称，最大的增生发生在外侧面。这些结果在冰岛语境中是连贯的，并且允许自10 Ma以来首次重建冰岛北部的演化。

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