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

9705773 McDowell 美国西南部的许多重要构造特征延伸到墨西哥，但这些特征都被埋藏在西马德雷山脉广阔的火成岩省之下。 这些特征包括北美克拉通的南部范围、晚元古代裂谷边缘、较年轻的新生地壳以及莫哈韦-索诺拉大剪切带的东南延续。 最近的一些重建南美和北美之间板块位置的构造综合需要了解这些现在被火山覆盖的特征的位置，以区分模型。 该项目将利用较年轻火山的同位素污染作为岩浆上升过程中围岩特征的指标。 结果应该有助于更好地定位重要的构造边界和其他特征，而这些特征现在在厚厚的火山岩堆下是无法到达的。

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.