Johnson Granite Porphyry | |
---|---|
Stratigraphic range: 85.4 Ma [1] | |
Type | Geological formation |
Area | 1,100 square kilometres (420 sq mi) |
Location | |
Location | Yosemite National Park |
Country | United States of America |
Type section | |
Named for | Johnson Peak |
Location | Yosemite National Park |
Johnson Granite Porphyry is found in Tuolumne Meadows, Yosemite National Park.
Johnson Granite Porphyry was named for Johnson Peak, the highest mountain in Tuolumne Meadows, Yosemite National Park. [1]
Its area is estimated at 1,100 square kilometres (420 sq mi), the exposed area covering roughly 40 square kilometres (15 sq mi). [2] Johnson Granite Porphyry is part of the Tuolumne Batholith. [3] Its boundaries are difficult to trace, and are irregular. [1] It is both the youngest, and the most siliceous rock of Tuolumne Intrusive Suite. [4] [5]
The innermost, most felsic part of the Tuolumne Batholith is the Johnson Granite Porphyry. [6] It is a highly irregular, elongated body. Completely surrounding it is the much larger body of Cathedral Peak granite. [1]
Field observations and magnetic fabrics suggest an extrusive event, that is, Johnson Granite Porphyry may record possible volcanism. This may relate to deformation along active shear zones. [7] [5] [8]
Johnson Granite Porphyry is composed of
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