Geology and Nonrenewable Minerals Chapter 12

Case Study: Real Cost of Gold Gold for 1 wedding band produces waste = to weight of 3 cars- Waste typically left at mine Toxins used to extract (cyanide salts & mercury)

WHAT ARE THE EARTH’S MAJOR GEOLOGICAL PROCESSES AND HAZARDS? Section 12-1

The earth is a dynamic planet Geology -study of dynamic processes occurring on the earth’s surface and in its interior. Three major concentric zones. 1.core =innermost zone—extremely hot, with a solid inner part encircled by a liquid core of molten /semisolid material. 2.mantle—solid rock, but under its rigid outermost part is the asthenosphere, a zone of hot, partly melted rock that flows. 3. Crust – outermost / thinnest Continental vs Oceanic crust The combination of the crust and the rigid outermost part of the mantle (above the asthenosphere) is called the lithosphere.

Fig. 12-2, p. 277 Volcanoes Folded mountain belt Abyssal floor Oceanic ridge Abyssal floor Trench Craton Abyssal hills Abyssal plain Oceanic crust (lithosphere) Continental shelf Continental slope Continental rise Convection cells cause rock to move Causes lithosphere to break up into a dozen tectonic plates. Continents have split apart and joined as tectonic plates drifted atop the earth’s asthenosphere.

Plate Boundaries –When two oceanic plates collide, a trench ordinarily forms at the boundary between the two plates. –When an oceanic plate collides with a continental plate, the continental plate usually rides up over the denser oceanic plate and pushes it down into the mantle in a process called subduction. –The area where this collision and subduction takes place is called a subduction zone. –Tectonic plates can also slide and grind past one another along a fracture (fault) in the lithosphere—a type of boundary called a transform fault.

Fig. 12-3, p. 277 Spreading center Ocean trench Subduction zone Oceanic crust Continental crust Continental crust Continental crust Material cools as it reaches the outer mantle Cold dense material falls back through mantle Hot material rising through the mantle Mantle convection cell Two plates move towards each other. One is subducted back into the mantle on a falling convection current. Mantle Hot outer core Inner core

The earth’s major tectonic plates

The San Andreas Fault

Internal pressure in a volcano can cause lava, ash, and gases to be ejected

An earthquake has certain major features and effects

Richter Scale –Magnitude is measured by seismograph –Richter scale -each unit has amplitude 10 times greater than the next smaller unit. –Insignificant (less than 4.0 on the Richter scale). –Minor (4.0–4.9). –Damaging (5.0–5.9). –Destructive (6.0–6.9). –Major (7.0–7.9). –Great (over 8.0). The largest recorded earthquake occurred in Chile on May 22, 1960 and measured 9.5 on the Richter scale.

How a tsunami forms

Earthquakes on the ocean floor can cause huge waves called tsunamis They can travel across the ocean at the speed of a jet plane. In deep water the waves are very far apart— sometimes hundreds of kilometers—and their crests are not very high. As a tsunami approaches a coast, it slows, its wave crests squeeze together, and heights grow rapidly. Hits a coast as a series of towering walls of water Between 1900 and 2010, tsunamis killed an estimated 280,000 people along the Pacific Ocean.

Tsunamis 101 (National Geographic Video) hic.com/video/environment/e nvironment-natural- disasters/tsunamis/tsunami- 101/

HOW ARE THE EARTH’S ROCKS RECYCLED? Section 12-2

Minerals A mineral is an element or inorganic compound that occurs naturally in the earth’s crust as a solid with a regular internal crystalline structure. Can consist of a single element such as gold, silver, and diamond (carbon). Most of the more than 2,000 identified minerals occur as inorganic compounds formed by various combinations of elements, such as salt (sodium chloride or NaCl) and quartzite (silicon dioxide or SiO 2 ).

There are three major types of rocks Rock is a solid combination of one or more minerals found in the earth’s crust. –Some kinds of rock, such as limestone and quartzite, contain only one mineral while most consist of two or more minerals, such as granite—a mixture of mica, feldspar, and quartz crystals. –Three broad classes: Sedimentary rock (e.g. sandstone, limestone). Igneous rock (e.g. granite). Metamorphic rock (e.g. slate, marble).

Simplified rock cycle Takes place over millions of years

WHAT ARE MINERAL RESOURCES AND WHAT ARE THE ENVIRONMENTAL EFFECTS OF USING THEM? Section 12-3

We use a variety of nonrenewable mineral resources A mineral resource is a concentration of naturally occurring material from the earth’s crust that can be extracted and processed into useful products and raw materials at an affordable cost. –Found and extracted more than 100 minerals from the earth’s crust. –Examples are fossil fuels (such as coal), metallic minerals (such as aluminum and gold), and nonmetallic minerals (such as sand and limestone). –Minerals are classified as nonrenewable resources.

We use a variety of nonrenewable mineral resources An ore is rock that contains a large enough concentration of a particular mineral—often a metal—to make it profitable for mining and processing. –High-grade ore vs. Low-grade ore Examples: Aluminum, steel, copper, gold

Each metal resource that we use has a life cycle

There are several ways to remove mineral deposits I. Shallow mineral deposits are removed by surface mining by: –Removing vegetation. –Removing the overburden or soil and rock overlying a useful mineral deposit. –Placing waste material set aside in piles, called spoils. 1. Open-pit mining

There are several ways to remove mineral deposits 2. Strip mining is useful and economical for extracting mineral deposits that lie in large horizontal beds close to the earth’s surface. A. Area strip mining is used where the terrain is fairly flat; a gigantic earthmover strips away the overburden, and a power shovel removes the mineral deposit. B. Contour strip mining is used mostly to mine coal on hilly or mountainous terrain.

There are several ways to remove mineral deposits 3. Mountaintop removal uses explosives, large power shovels, and huge machines called draglines to remove the top of a mountain and expose seams of coal. Colbert Report Mountain Top Mining /coal-comfort---margaret-palmer II. Subsurface mining removes minerals from underground through tunnels and shafts.

Harmful effects of extraction, processing, and use of nonrenewable mineral or energy resources Mining produces 75% of all solid waste in US & is a major cause of air and water pollution. Acid mine drainage = sulfuric acid

Types of mining Open pit, strip, contour strip, and mountaintop removal Open pit Strip Contour strip Mt. Top Removal Subsurface mining disturbs 1/10 th as much land as surface mining & usually produces less waste

Removing metals from ores has harmful environmental effects Ore mining typically has two components: –Ore mineral, containing the desired metal. –Waste material (tailings) Heating ores to release metals is called smelting. –Without effective pollution control equipment, smelters emit enormous quantities of air pollutants, including sulfur dioxide and suspended particles.

HOW LONG WILL SUPPLIES OF NONRENEWABLE MINERAL RESOURCES LAST? Section 12-4

Mineral resources are distributed unevenly Abundant : iron and aluminum. Scarce: Manganese, chromium, cobalt, and platinum. ( Strategic metal resources ) Uneven distribution of mineral resources. USA, Canada, Russia, South Africa, and Australia— supply most of world’s mineral resources Economic Depletion- costs too much to exploit remaining deposits What to do after economic depletion? Recycle/reuse, waste less, find substitute, do without

Market prices affect supplies of nonrenewable minerals Most well-developed countries use subsidies, taxes, regulations, and import tariffs to control the supply, demand, and price of minerals. Most mineral prices are kept artificially low. Extraction of lower grades of ore is possible due to technological advances. Good idea? Biomining (in-place, or in situ) -use or microorganisms to break down rock material and extract minerals. Importance of rare earth metals – see p. 291

Can we get more of our minerals from the oceans? Some ocean mineral resources are dissolved in seawater, but Low concentrations take more energy and money than they are worth. Hydrothermal ore deposits are rich in minerals such as copper, lead, zinc, silver, gold, and some of the rare earth metals. Growing interest in deep-sea mining. Manganese nodules cover large areas of ocean floor. (contain rare earth metals)

HOW CAN WE USE MINERAL RESOURCES MORE SUSTAINABLY? Section 12-5

We can find substitutes for some scarce mineral resources Human ingenuity will find substitutes. Current materials revolution in which silicon and other new materials, particularly ceramics and plastics, are being used as replacements for metals. Finding substitutes for scarce minerals through nanotechnology. We can recycle and reuse valuable metals

We can use nonrenewable mineral resources more sustainably

Three big ideas Dynamic forces that move matter within the earth and on its surface recycle the earth’s rocks, form deposits of mineral resources, and cause volcanic eruptions, earthquakes, and tsunamis. The available supply of a mineral resource depends on how much of it is in the earth’s crust, how fast we use it, the mining technology used to obtain it, its market prices, and the harmful environmental effects of removing and using it. We can use mineral resources more sustainably by trying to find substitutes for scarce resources, reducing resource waste, and reusing and recycling nonrenewable minerals.