ADVANCES IN UNDERSTANDING THE TECTONO-MAGMATIC HISTORY OF THE NORTH AMERICAN CORDILLERA – TRANSFORMATIVE CONTRIBUTIONS FROM PROF. JASON B. SALEEBY

Professor Jason Saleeby’s major contributions to the geology of the North American Cordillera span a period of almost forty years. He spearheaded numerous innovative research projects spanning a wide range of geologic sub-disciplines, advised many undergraduate and graduate students, teamed with many postdocs and collaborators, all of whom consider him a lifelong friend. Here I summarize and review the most important concepts that were put forward by Prof. Saleeby and his collaborators over the years with examples and their implications for North America and beyond.

The tempo of arc magmatism is punctuated by episodes of high flux, which is a fundamental observation. The overall crustal and lithospheric architecture of the arc, from shallow, volcanic levels, down to the base of the lithosphere for the Sierra Nevada, provides the modern template for arc composition and structure globally. The ability and necessity of removal of the lower parts of the arc lithosphere, is another contribution of great significance to understanding the tectonic evolution of continental arcs. Dr. Saleeby also had major contributions in understanding the geometry of slab segmentation along the strike of southwestern North America and the implications of this process. His research investigated the tectonic signature of shallow subduction and tectonic underplating during the Laramide orogeny along the Mojave corridor; this has significant implications for understanding shallow subduction globally, the requirement of buoyant seamounts on the downgoing plate and the alteration of the upper plate by accreting trench-sediments to the bottom of arc sections. Dr. Saleeby’s work in metamorphic pendants from California and SE Alaska is an exponential effort in understanding the deformation and metamorphism patterns of rocks caught in between large plutons. His work also was influential in demonstrating the significance of intra-arc strike-slip motions. His classic early work on western Sierra Nevada framework rock geology has had a great impact on understanding accretion of terranes in general, and ophiolite accretion in particular. In addition, his research in SE Alaska has had a major impact on documenting west verging thrust systems within the orogen and their significance to the mass balance of arc lithosphere.