General Geology Notes 8 30 17 PDF

Preview

Summary

Download General Geology Notes 8 30 17 PDF

Description

How do we Know? What the Earth is made up of? : ● Volcanoes and xenolith (foreign rock) ● Seismic Waves ○ Density differences ■ Density on earth is based on composition ● Estimating original composition of earth from meteorites ● Deepest hole drilled in earth is 10km ● Can’t drill too deep into the crust because it would get too hot ● Never drilled into the mantle before, wait for the mantle to come up by itself, usually by eruption of volcanoes ● As magma forms, it rises up to the crust and erupts to the surface ● Magnetic field Oceans: ● Water in oceans came from meteorites that formed Earth ● As Earth’s T increased, water turned to steam ● As Earth cooled the water condensed and filled basins forming oceans ● Turned into water-rich atmosphere ● It rained for about 1 million years from the atmosphere Earth’s Early Atmosphere: ● Early atmosphere: Co2, Methane, N, Ammonia, Sulfur ● Age of Earth: 4.6 Billion years ● Blue- green algae (3.8 billion years ago) began to produce oxygen through photosynthesis, first life ○ Sunlight + Co2 = Oxygen Mineral Specimens: ● Rocks are made up of minerals and minerals are made up of the elements of the periodic table Why Study Minerals? : ● Minerals are the building blocks of the planet ● Minerals are important to humans: ○ Industrial Minerals ○ Ore Minerals (copper, silver, gold etc.) ○ Gem Minerals What is a Mineral? : ● Naturally occurring

● ● ● ●

Solid Formed geologically, some form when water evaporates, some form from gas Mostly inorganic (It means it was never a living thing) Definite chemical composition (has the same elements that make it up) ○ Simple: quartz (Si and O2) and calcite (CaCO3) and Halite (NaCl, salt) ○ Complex: Biotite, Hornblende ● Crystalline structure ○ Atoms in a mineral are arranged in a specific order ○ A solid with disordered atoms is called a glass, not minerals What is a Crystal? : ● Ordered atoms packed tightly together ● Chemical bonds ● The way atoms are packed defines the crystal structure ● A mineral with a geometric form and symmetrically arranged faces ○ Ex: Halite, Diamond, Staurolite, Quartz, Garnet, Stibnite, Calcite, Kyanite Importance of Bonds: ● Diamond and graphite are Carbon (C) ○ Diamond- strong bonds; hardest mineral ○ Graphite- weak bonds; softest mineral Atom Structure: ● Atom: the smallest piece of an element that still has the properties of that element ● Nucleus is made up of neutron and protons ● Around the nucleus is electrons Reading the Periodic Table: ● Atom number = number of protons ● Atomic mass number = number of protons and neutrons Isotopes: ● A variation of a particular element ● Two of an element have: ○ The same number of protons ○ Different number of neutrons Why are Isotopes important? : ● Some isotopes are radioactive ● Geologists can date materials based on this decay ● Discovery of how old the earth is the most important contribution

Formation of Minerals: ● From magma ● From a gas ○ Happens in volcanic setting, things like sulfur, smells like rotten eggs ● During metamorphism ● From a solution ○ Ex: salt, sea water evaporates and leaves salt Mineral Classification: ● Only about 50 minerals are abundant ● 98% of crustal mineral mass is from eight elements ● Silicates: mineral with silicon and oxygen at the end of its chemical formula Silicate Minerals: ● Known as “the rock-forming minerals” ● They dominate earth’s crust and mantle ○ Made of oxygen and silicon with other atoms ○ Ex: quartz - SiO2 Other Mineral Groups: ● Oxides, ex: magnetite ● Sulfides, ex: galena, has sulfate at the end ● Sulfates, ex: gypsum ● Carbonates, ex: calcite, have carbon and oxygen at the end ● Native elements, ex: gold or copper, just made up of one element From Minerals to Rocks: ● Metamorphic ● Igneous ● sedimentary...