Radiogenic Isotope Characteristics of Late Cretaceous and Tertiary Igneous Rocks Across the Southern Margin of the North American Craton, Northern Sierra Madre Occidental, MX

[70705773]麦克道尔美国西南部的许多重要构造特征延伸到墨西哥，然而，这些特征被埋藏在西马德雷山脉的巨大火成岩省之下。这些特征包括北美克拉通的南缘、晚元古代裂陷边缘、较年轻的幼年地壳以及莫哈韦-索诺拉巨型盆地的东南延伸。最近几项重建南美和北美之间板块位置的构造综合研究需要了解现在被火山覆盖的这些特征的位置，以便区分不同的模型。该项目将利用较年轻火山岩的同位素污染作为岩浆上升过程中围岩特征的指标。结果将有助于更好地定位重要的构造边界和其他特征，这些特征目前在厚厚的火山堆下难以探测到。

9705773 McDowell A number of important tectonic features of the southwestern United States extend into Mexico, however these become buried under the vast igneous province of the Sierra Madre Occidental. These features include the southern extent of the North American craton, a late proterozoic rifted margin, younger juvenile crust and the southeastward continuation of the Mojave-Sonora megashear. Several recent tectonic syntheses reconstructing plate positions between south and north America require knowledge of the location of these features now covered by volcanics to discriminate between models. The project will utilize isotopic contamination of the younger volcanics as an indicator of the character of the wall rocks during magma ascent. Results should help to better locate important tectonic boundaries and other features, now inaccessible under the thick volcanics pile.