Model for the origin of the Yakutat block, an accreting terrane in the northern Gulf of Alaska
Model for the origin of the Yakutat block, an accreting terrane in the northern Gulf of Alaska
复制标题
亚库塔特地块的起源模型，阿拉斯加湾北部的一个增生地体
DOI：
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发表时间：
1983
期刊：
影响因子：
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通讯作者：
T. R. Bruns
中科院分区：
文献类型：
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作者：
T. R. Bruns
一个海洋和大陆的复合地体，雅库特块体，目前正在阿拉斯加湾北部与北美碰撞并增生。海洋地球物理资料表明，该地块在上新世和第四纪随太平洋板块移动，但对其之前的运动历史不确定。有一种模型可以解释该地块某些观测到的地质和构造特征，即它起源于北美下方库拉-法拉隆扩张中心的俯冲作用。在该模型中，形成雅库塔地块玄武岩基底的扩张中心被一条长400 ~ 500 km的左旋变形断层向南偏移。大约45亿年前，北部扩张中心的俯冲作用将北美大陆边缘的一部分切下，与库拉板块相连，并引发了复合地块的北移，形成了雅库塔地块。始新世和渐新世时期，南扩张中心向北美的迁移截断了南部的雅库塔地块，留下了一个化石断裂带，现在被认为是过渡断裂。南部扩张中心大约25万年前俯冲，雅库特块体随后随太平洋板块移动到阿拉斯加南部。
A composite oceanic and continental terrane, the Yakutat block, is currently colliding with and accreting to North America in the northern Gulf of Alaska. Marine geophysical data indicate that the block has moved with the Pacific plate during Pliocene and Quaternary time, but are indeterminant about its previous movement history. A model that explains some observed geologic and structural features of the block is that it originated as a result of subduction of the Kula-Farallon spreading center beneath North America. In this model, the spreading center that formed the basaltic basement of the Yakutat block was offset from a spreading center to the south by a left-lateral transform fault 400–500 km long. Subduction of the northern spreading center about 45 m.y. ago sliced off part of the North America continental margin, attached it to the Kula plate, and initiated northward movement of the composite terrane as the Yakutat block. During Eocene and Oligocene time, migration of the southern spreading center toward North America truncated the Yakutat block on the south and left a fossil fracture zone that is now seen as the Transition fault. The southern spreading center subducted about 25 m.y. ago, and the Yakutat block has since traveled with the Pacific plate to southern Alaska.