rocks
The document is an educational resource for Grade 11/12 students, focusing on the study of minerals and rocks, including their properties, types, and significance in daily life.
Bowen's Reaction Series and Crystallization
Bowen's reaction series illustrates the sequence of mineral crystallization from cooling magma.
Developed by petrologist Norman L. Bowen in the early 1900s.
Begins with melting igneous rocks at approximately 1200°C.
Two branches: discontinuous (olivine to biotite mica) and continuous (calcium-rich to sodium-rich plagioclase feldspar).
Eventually merges into potassium feldspar, muscovite mica, and quartz.
Types of Igneous Rocks: Extrusive and Intrusive
Igneous rocks are categorized based on their formation location and cooling rates.
Extrusive igneous rocks form from magma that erupts and solidifies on Earth's surface, resulting in fine-grained textures.
Examples include obsidian (glassy texture), andesite, and pumice (lightweight with holes).
Intrusive igneous rocks crystallize within the Earth's crust, featuring medium to coarse grains.
Types of intrusive bodies include concordant (sills) and discordant (dikes, laccoliths, batholiths).
Classification of Igneous Rocks by Texture
Igneous rocks can be classified based on their texture and mineral composition.
Textures include aphanitic (fine-grained), phaneritic (coarse-grained), pegmatitic (large crystals), vesicular (gas holes), porphyritic (larger crystals in smaller matrix), amygdaloidal (vesicles filled with minerals), and pyroclastic (rock fragments).
Mineral composition categories: felsic (light-colored, high silica), intermediate (medium gray/green), mafic (dark gray/black), and ultramafic (very dark green/black).
Naming Igneous Rocks Using Binary System
Igneous rocks are named based on their texture and composition.
The binary system categorizes rocks into extrusive (rhyolite, andesite, basalt) and intrusive (granite, diorite, gabbro).
Felsic rocks are silica-rich, while mafic rocks are silica-poor.
Intermediate rocks have equal amounts of light and dark minerals.
Common Igneous Rocks from Pyroclastic Eruptions
Certain igneous rocks are specifically formed from pyroclastic eruptions.
Felsic: rhyolitic tuff.
Intermediate: andesitic tuff.
Mafic: basaltic tuff.
Formation and Types of Sedimentary Rocks
Sedimentary rocks form through the lithification of sediments, showcasing distinct layering.
Formed from organic, mechanical, or chemical sediments.
Lithification involves compaction, cementation, recrystallization, and chemical changes.
Clastic sedimentary rocks are made from preexisting rock fragments, while non-clastic rocks can be biological or chemical.
Clastic and Non-Clastic Sedimentary Rocks
Sedimentary rocks are classified into clastic and non-clastic types based on their origin.
Clastic rocks are formed from weathered rock fragments, categorized by grain size (e.g., conglomerate, sandstone, shale).
Non-clastic rocks include biological (coal, limestone) and chemical (rock salt, gypsum) formations.
Key Processes in Sedimentary Rock Formation
The processes involved in the formation of sedimentary rocks include compaction and cementation.
Compaction occurs when sediments are squeezed together under pressure.
Cementation involves the binding of sediments by minerals precipitating from water.
Metamorphic Rocks and Their Formation
Metamorphic rocks are formed from existing rocks altered by heat, pressure, and chemical processes.
Metamorphism can occur through recrystallization, neomorphism, and metasomatism.
Two main types of metamorphism: contact (local) and regional (large areas).
Classification of Metamorphic Rocks
Metamorphic rocks are classified as foliated or nonfoliated based on their texture.
Foliated rocks exhibit parallel layers (e.g., schist, gneiss).
Nonfoliated rocks lack layering (e.g., marble, quartzite).
The Rock Cycle and Its Processes
The rock cycle illustrates the interrelationship between igneous, sedimentary, and metamorphic rocks.
Rocks can transform from one type to another through various geological processes.
The cycle emphasizes the dynamic nature of Earth's geology.