Taconian orogeny in the New England Appalachians: Collision between Laurentia and the Shelburne Falls arc
Taconian orogeny in the New England Appalachians: Collision between Laurentia and the Shelburne Falls arc
复制标题
新英格兰阿巴拉契亚山脉的塔科尼亚造山运动：劳伦西亚与谢尔本瀑布弧之间的碰撞
DOI：
--
复制
发表时间：
1998
期刊：
影响因子：
--
通讯作者：
H. Stoll
中科院分区：
文献类型：
--
作者：
Paul Karabinos;S. Samson;J. Hepburn;H. Stoll
新英格兰西部奥陶系塔肯造山的构造模式通常会引发劳伦斯边缘与被识别为布朗森山弧的岩浆弧之间的碰撞。然而，在马萨诸塞州中部和新罕布夏州南部，布朗森山弧中的岩石年龄为454 Ma至442 Ma，因此比新英格兰西部和纽约东部的大部分塔克期变形和变质作用要年轻，后者始于470 Ma。U-Pb和单颗粒蒸发锆石年龄结合地球化学分析表明，存在一个更古老的岩浆弧--谢尔本瀑布弧，它形成于485-470 Ma的布朗森山弧以西。谢尔本瀑布是早奥陶世在向东倾斜的俯冲带上方形成的。塔科尼亚造山作用是劳伦蒂亚和谢尔本瀑布弧约475-470 Ma开始碰撞的结果。年轻的布朗森山弧形形成于向西倾斜的俯冲带之上，该俯冲带在塔肯造山运动的末期及之后沿着新增生的地体的东缘发育。当劳伦蒂亚和伊阿普图斯之间的板块汇聚被新发展的西倾俯冲带容纳，而不是通过塔肯冲断带的地壳缩短时，塔孔造山运动结束。新英格兰阿巴拉契亚山脉的构造历史与中奥陶世劳伦蒂亚和冈瓦那原始安第斯边缘之间的碰撞不一致。
Tectonic models of the Ordovician Taconian orogeny in western New England usually invoke a collision between the Laurentian margin and a magmatic arc identified as the Bronson Hill arc. However, in central Massachusetts and southern New Hampshire, rocks in the Bronson Hill arc are 454 to 442 Ma and therefore younger than much of the Taconian deformation and metamorphism in western New England and eastern New York, which began by 470 Ma. U-Pb and single-grain evaporation zircon ages combined with geochemical analyses reveal the presence of an older magmatic arc, the Shelburne Falls arc, that formed west of the Bronson Hill arc at 485 to 470 Ma. The Shelburne Falls arc formed above an east-dipping subduction zone by the Early Ordovician. The Taconian orogeny was the result of the collision between Laurentia and the Shelburne Falls arc beginning ca. 475 to 470 Ma. The younger Bronson Hill arc formed above a west-dipping subduction zone that developed along the eastern edge of the newly accreted terrane during the final stages of and subsequent to the Taconian orogeny. The Taconian orogeny ended when plate convergence between Laurentia and Iapetus was accommodated by the newly developed west-dipping subduction zone instead of by crustal shortening in the Taconian thrust belt. The tectonic history of the New England Appalachians is inconsistent with a Middle Ordovician collision between Laurentia and the proto-Andean margin of Gondwana.