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麦克道尔美国西南部的许多重要构造特征延伸到墨西哥，但这些特征被埋在广阔的马德雷西部火成岩省之下。这些特征包括北美克拉通的南部范围、晚元古代裂谷边缘、年轻的年轻地壳和莫哈韦-索诺拉巨型地壳向东南的延续。最近的几个构造综合体重建了南美洲和北美之间的板块位置，需要了解这些特征现在被火山岩覆盖的位置，以区分不同的模型。该项目将利用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示器。结果应该有助于更好地定位重要的构造边界和其他特征，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.