Tuesday January 29, 2013 (Bowen’s Reaction Series)

The Launch Pad Tuesday, 1/29/13 Rocks that are formed inside the Earth are called ________________ rocks. Rocks formed on the surface are called _____________ rocks. slowly far underground quicker nearer the surface very fast on the surface after releasing gases very fast on the surface before releasing gases intrusive extrusive Describe how these rocks cooled.

The Launch Pad Tuesday, 1/29/13 Complete the following sentences: Coarse-textured igneous rocks usually have ______crystals because they cooled ______ underground, which makes them ___________ rocks. Fine-textured igneous rocks usually have ______ crystals because they cooled _______ above or just underground, which makes them either __________________ rocks. Glassy-textured igneous rocks usually have _________ crystals because they cooled ___________above ground, which makes them ____________rocks. large slowlyintrusive small quickly extrusive or intrusive microscopic very quickly extrusive

Announcements Happy Day!

Announcements I will be available after school today until 5:00.

Assignment Currently Open Summative or Formative? Date IssuedDate Due Date Into GradeSpeed Final Day Quiz 15S512/11 1/15 TODAY Quiz 16S11/18 1/242/7 WS – Igneous Rocks F61/282/1

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Yesterday we learned that there are two criteria for classifying igneous rocks: texture (grain size) and mineral composition. Mineral composition is, of course, the types of minerals that make up the rock. The crystallization of magma is explained by Bowen’s Reaction Series, which shows the order of mineral crystallization. This is influenced by crystal-settling in the magma. Bowen’s Reaction Series is shown on the next slide.

Figure 3.13 Bowen’s reaction series

Magma, with its diverse chemistry, crystallizes over a temperature range of at least 450 o C. Therefore, as magma cools, certain minerals crystallize first, at relatively high temperatures. At successively lower temperatures, other minerals crystallize. This arrangement of minerals became known as Bowen’s Reaction Series.

The first mineral to crystallize from a mass of magma is olivine. Further cooling results in the formation of pyroxene, as well as plagioclase feldspar. At intermediate temperatures, the minerals amphibole and biotite begin to crystallize.

During the last stage of crystallization, after most of the magma has solidified, the minerals muscovite and potassium feldspar may form. Finally, quartz crystallizes from any remaining temperature.

In nature, we find that minerals that form in the same general temperature range on Bowen’s chart are found together in the same igneous rocks. For example, the minerals quartz, potassium feldspar, and muscovite (or hornblende) are typically found together as major components of the igneous rock granite.

Figure 3.13 Bowen’s Reaction Series

Figure 3.13

Knowledge Check What is the theme of Bowen’s Reaction Series? Different minerals crystallize at different temperatures as magma cools.

Worksheet Bowen’s Reaction Series