Final answer:
The Sierra Nevada Batholith is a large mass of igneous rock in California formed during Late Mesozoic subduction when an oceanic plate subducted beneath a continental plate. The tectonic setting led to the formation of both volcanoes and granitic plutons, which now make up the Sierra Nevada mountain range.
Step-by-step explanation:
The Sierra Nevada Batholith is a large geologic formation spanning 400 miles through the middle of California, known for its impressive granite formations like Yosemite's Half Dome. It forms part of the Sierra Nevada mountain range and consists of the exposed cores of ancient volcanoes. This batholith is a byproduct of tectonic convergence and subduction processes during the Late Mesozoic era, roughly the same period as the Rocky Mountains' formation. As the oceanic plate was subducted under the continental plate, the resulting high temperatures and pressures caused the melting of rocks, which eventually solidified into the massive granite batholiths we see today.
The tectonic setting at that time was one of subduction, where an oceanic plate dives beneath a continental plate, leading to intense geological activity, including the formation of volcanoes and the intrusion of plutonic rocks. Emplacement of plutons within the Sierra Nevada occurred due to the melting of the subducting oceanic crust and the overlying continental crust, leading to the rise of molten rock (magma) which, upon cooling, formed the granitic plutons that make up much of the Sierra Nevada Batholith.
The tectonic environment responsible for the Sierra Nevada Batholith would have resulted in various types of crystalline igneous rocks forming simultaneously as the magma cooled and solidified at different rates under different conditions. Modern examples of similar subduction processes are occurring in the Cascades, where the subduction of the Juan de Fuca and Gorda Plates is actively forming volcanoes. Understanding these geological processes aids in comprehending the complex history of Earth's lithosphere and its continual transformation through tectonic activity.