Paleomagnetic Constraints Upon the Displacement History of the Alexander Terrane, Alaska

异地地体的碰撞和吸积主导了太平洋西北部和阿拉斯加的中、新生代历史。对接的最大地体是合并后的地体，有时被称为“不列颠哥伦比亚省下部”，之所以这样叫，是因为像Wrangellia这样的包含地体具有明显的指示低纬度的主要古地磁矢量。然而，来自另一个被包括的地体(Alexander Terrane)的现有数据表明，自晚三叠世以来没有纬向运动。由于Alexander Terrane位于Wrangellia的南部，存在严重的空间和时间问题。该项目将试图通过对这些地体的样品收集进行广泛的古地磁分析来解决这一悖论，包括消除重叠和用40Ar/39Ar技术确定年龄。这些结果为解决太平洋西北地体组装的构造序列提供了可能性。

The collision and accretion of allochthonous terranes dominates the Mesozoic and Cenozoic history of the Pacific Northwest and Alaska. The largest terrane to dock was the amalgamated terrane sometimes referred to as "Baja British Columbia", so-called because included terranes such as Wrangellia have apparent primary Paleomagnetic vectors indicating low latitudes. However, available data from another included terrane (Alexander terrane) indicates no latitudinal movement since the late Triassic. As Alexander terrane lies to the south of Wrangellia, a severe spatial and timing problem exists. This project will attempt to resolve the paradox by extensive paleomagnetic analysis of sample collections from these terranes, including removal of overprints and determination of ages by 40Ar/39Ar techniques. Results offer the potential to resolve the tectonic sequence of assembly of the Pacific north- west terranes.