Sierra Nevada Geology: Formation & Sequoias in Yosemite, Kings Canyon & Sequoia Parks, Study notes of Geology

Download Sierra Nevada Geology: Formation & Sequoias in Yosemite, Kings Canyon & Sequoia Parks and more Study notes Geology in PDF only on Docsity! Geol 104 Lecture 20 Sierra Nevada: Yosemite, Kings Canyon and Sequoia NP 3/24/05 Dr. Stewart 1 I. Introduction A. We will lump the parks of the Sierra Nevada into one lecture B. Forming the Sierra Nevada 1. Paleozoic-Mesozoic accreted terrains 2. Sevier Orogeny 3. Eocene Uplift C. Pliocene/Pleistocene Glacial Features D. Big Trees! I. Location A. Western margin of Basin and Range 1. Owens’ Valley Fault marks the east side of Sierra Nevada 2. Basin and range province is to the East B. Great Valley of CA is to the West – recall this is the former for-arc basin of subduction zone C. Sierra Nevada Runs length of CA - Related Mesozoic plutons extend down through Baja Peninsula II. Formation of Sierra Nevada Mountains A. Paleozoic-Mesozoic subduction (Antler Orogeny) 1. Accreted Terrains were added to Laurentia - Blocks of crust sutured to Laurentia during subduction reversals 2. These represent the crust upon which subduction during the Sevier Orogeny built a volcanic Arc - Think Andes volcanoes on SA crust B. Sevier Orogeny (165-80 Ma) 1. Accretionary Prism and Forearc Basin - Recall coastal ranges of CA and the Great Valley 2. Volcanic Arc builds on the crust a. The crustal magma chambers that feed these volcanoes are later exposed as the Sierra Nevada Batholith b. A Batholith is a huge (100s km x 100s km), thick body of intrusive igneous rock 3. Fold and thrust belt behind the arc - Recall Death Valley, and Glacier National Park C. Laramide uplift and Basin and Range Extension 1. Laramide (80-40 Ma) Orogeny a. Shallowing of slab causes volcanisms to migrate eastward - Recall Absaroka Volcanics, Devils Tower b. Uplifts the old arc and much of the crust to the east i. Recall Colorado Plateau, and Rocky Mountain NP ii. Upper crust (volcanics) is eroded and exposes the deeper crust - Batholith and the rocks it intruded (accreted terrain)