GEOL 1013 Lecture Notes - Lecture 1: Granodiorite, Geothermal Gradient, Parent Rock
3 Nov 2017
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Document Summary
I is formed by the melting of rocks. Igneous rocks form by the crystallization of magma. 2 types of igneous rock: volcanic (or extrusive) igneous rocks, rapid cooling, plutonic (or extrusive) igneous rocks, slow cooling. Types of volcanic igneous rock textures: glassy, aphanitic, pyroclastic. Surface of the flow can be: pahoehoe (smooth and ropy, aa (jagged) Vesicles are holes left by gas bubbles trapped in the magma. Characteristic of the upper part of lava flows. Vesicles later filled in with secondary minerals are called amygdales and the texture is called. Columnar jointing occurs when the lava is crystallizing. If basaltic lava flows underwater, it commonly forms shapes called pillows. Shield volcanoes are made from basaltic lava flows. Fissure eruptions also happen on the sea floor all along the ocean ridges. They form large volumes of pillow basalt on the sea floor. Andesitic, dacitic and rhyolitic eruptions: more viscous than basaltic magmas(more sio2 and lower temp).
