An Investigation of Crustal and Upper Mantle Magmatic Sources in the High Plains Province, New Mexico and Colorado, A Unique View into Late Cenozoic Magmatic...

新生代期间，火山作用和伸展构造作用席卷了美国西部的大片地区。近年来的研究对美国西部的构造运动和岩浆作用之间的关系提供了许多见解，但与伸展动力有关的问题仍然悬而未决。高平原的新生代火山岩为这类问题提供了独特的视角。这些火山岩在成分上大致相似，与格兰德裂谷中的火山岩几乎同时代，并向西南进入亚利桑那州。然而，高平原火山田位于里奥格兰德裂谷以东100-200公里处，该地区远远超出了地壳伸展的影响。我们的初步研究表明，火山岩成分的空间和时间变化(例如，同位素变化)需要在源岩成分和地壳和地幔结构方面有明显的差异。对该火山场的详细研究将能够与伸展区域内的火山场进行比较，并为解释岩浆活动和伸展构造作用之间关系的物理模型提供必要的约束。

Volcanism and extensional tectonism spread across a broad region of the western U.S. during the Cenozoic. Studies in recent years have provided much insight into the relationship between the tectonism and magmatism in the western U.S., but unsolved questions relating to the driving forces for extension remain. The Cenozoic volcanic rocks of the High Plains provide a unique perspective on such problems. These volcanic rocks are broadly similar in composition and closely contemporaneous with volcanic fields in the Rio Grande Rift and southwestward into Arizona. However, the High Plains volcanic fields lie 100-200 km east of the Rio Grande Rift in an area well beyond the effects of crustal extension. Spatial and temporal variations in composition of volcanic rocks shown from our preliminary study (e.g., isotopic changes) require significant differences in source composition and crust and mantle structure. A detailed study of this volcanic field will enable comparison with fields within the region of extension and provide essential constraints for physical models explaining relationship between magmatism and extensional tectonism.