Geology and Minerals: Understanding Earth's Dynamic Processes and Nonrenewable Resources, Slides of Ecology and Environment

Download Geology and Minerals: Understanding Earth's Dynamic Processes and Nonrenewable Resources and more Slides Ecology and Environment in PDF only on Docsity! Geology and Nonrenewable Minerals Chapter 12 Docsity.com The earth is a dynamic planet • Geology is the science devoted to the study of dynamic processes occurring on the earth’s surface and in its interior. • Three major concentric zones. – The core is the earth’s innermost zone—extremely hot, with a solid inner part encircled by a liquid core of molten or semisolid material. – Surrounding the core is a thick zone called the mantle—solid rock, but under its rigid outermost part is the asthenosphere, a zone of hot, partly melted rock that flows. Docsity.com The earth beneath your feet is moving • The forces produced at these plate boundaries can cause earthquakes, erupting volcanoes and mountains to form. • Oceanic plates move apart from one another allowing magma, to flow up between them. • Much of the geologic activity at earth’s surface takes place at the boundaries between tectonic plates as they move in the resulting cracks. – Oceanic ridges may have peaks higher and canyons deeper than those found on the earth’s continents. Docsity.com The earth beneath your feet is moving – 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. Docsity.com Volcanoes release molten rock from the earth’s interior • An active volcano occurs where magma reaches the earth’s surface through a central vent or a long crack, called a fissure. • Many volcanoes form along the boundaries of the earth’s tectonic plates when one plate slides under or moves away from another plate. • Magma that reaches earth’s surface is called lava. • Volcanic activity can release large chunks of lava rock, glowing hot ash, liquid lava, and gases into the environment. Docsity.com Earthquakes are geological rock-and- roll events – 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). Docsity.com Earthquakes are geological rock-and- roll events • The largest recorded earthquake occurred in Chile on May 22, 1960 and measured 9.5 on the Richter scale. • The primary effects of earthquakes include shaking and sometimes a permanent vertical or horizontal displacement of the ground. These effects may have serious consequences for people and for buildings, bridges, freeway overpasses, dams, and pipelines. Docsity.com Earthquakes are geological rock-and- roll events • One way to reduce the loss of life and property damage is to examine historical records and make geologic measurements to locate active fault zones. – Map high-risk areas and establish building codes that regulate the placement and design of buildings in such areas. – People evaluate the risk and factor it into their decisions about where to live. – Engineers know how to make buildings and structures more earthquake resistant. Docsity.com Earthquakes on the ocean floor can cause huge waves called tsunamis • Tsunamis can be detected through a network of ocean buoys or pressure recorders located on the ocean floor to provide some degree of early warning sent through emergency warning centers. – Between 1900 and 2010, tsunamis killed an estimated 280,000 people along the Pacific Ocean. – The largest loss of life (279,900) occurred in December 2004 when a great underwater earthquake in the Indian Ocean with a magnitude of 9.15 caused a tsunami that generated waves as high as a five-story building. Docsity.com There are three major types of rocks • 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. • A few minerals 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 SiO2). Docsity.com 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). Docsity.com 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 contains a large concentration of the desired mineral. – Low-grade ore has a smaller concentration. – Aluminum (Al) is used for packaging and beverage cans and as a structural material in motor vehicles, aircraft, and buildings. Docsity.com We use a variety of nonrenewable mineral resources – Steel, an essential material used in buildings and motor vehicles, is a mixture (alloy) of iron (Fe) and other elements that are added to give it certain properties. – Copper (Cu), a good conductor of electricity, is used for electrical and communications wiring. – Gold (Au) is used in electrical equipment, tooth fillings, jewelry, coins, and some medical implants. Docsity.com Some environmental impacts of mineral use • Metals can be used to produce many products. • Life cycle of a metal—mining, processing, and using it— takes enormous amounts of energy and water and can disturb the land, erode soil, produce solid waste, and pollute the air, water, and soil. • The more accessible and higher-grade ores are usually exploited first. • As they are depleted, mining lower-grade ores takes more money, energy, water, and other materials, and increases land disruption, mining waste, and pollution. Docsity.com There are several ways to remove mineral deposits • Mountaintop removal uses explosives, large power shovels, and huge machines called draglines to remove the top of a mountain and expose seams of coal. • Subsurface mining removes minerals from underground through tunnels and shafts. Docsity.com Mining has harmful environmental effects • Scarring and disruption of the land surface. – Mountaintop removal destroys forests, buries mountain streams, and increases flood hazards. Wastewater and toxic sludge, produced when the coal is processed, are often stored behind dams in these valleys, which can overflow or collapse and release toxic substances such as arsenic and mercury. Docsity.com Mining has harmful environmental effects – In the United States, more than 500 mountaintops have been removed to extract coal and the resulting spoils have buried more than 1,100 kilometers (700 miles) of stream. – Surface mining in tropical forests and other tropical areas destroys or degrades vital biodiversity when forests are cleared and rivers are polluted with mining wastes. – Produces toxic waste material such as lead dust, which can cause lead poisoning and irreversible brain damage in children. Docsity.com Removing metals from ores has harmful environmental effects • Ore mining typically has two components: – Ore mineral, containing the desired metal. – Waste material. • Removing the waste material from ores produces waste piles called 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. • Chemicals can be used to remove metals from their ores. Docsity.com Mineral resources are distributed unevenly • The earth’s crust contains fairly abundant deposits of iron and aluminum. • Manganese, chromium, cobalt, and platinum are relatively scarce. • The earth’s geologic processes have not distributed deposits of nonrenewable mineral resources evenly among countries. Docsity.com Mineral resources are distributed unevenly • Five nations—the United States, Canada, Russia, South Africa, and Australia—supply most of the nonrenewable mineral resources used by modern societies. • Experts are concerned about four strategic metal resources—manganese, cobalt, chromium, and platinum—which are essential for the country’s economy and military strength. The United States has little or no reserves of these metals. Docsity.com Is mining lower-grade ores the answer? • Extraction of lower grades of ore is possible due to new earth-moving equipment, improved techniques for removing impurities from ores, and other technological advances in mineral extraction and processing. • Mining low-grade ores is limited by: – Increased cost of mining and processing larger volumes of ore. Docsity.com Is mining lower-grade ores the answer? – Increasing shortages of freshwater—which is needed to mine and process some minerals— especially in arid and semiarid areas. – Environmental impacts of the increased land disruption, waste material, and pollution produced during mining and processing. • Can use microorganisms that can break down rock material and extract minerals in a process called in-place, or in situ, mining or biomining. Docsity.com Can we get more of our minerals from the oceans? • Some ocean mineral resources are dissolved in seawater. • 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. Docsity.com We can use mineral resources more sustainably • Instead of asking how we can increase supplies of nonrenewable minerals, we should be asking, how can we decrease our use and waste of such resources? • Since 1990, a growing number of companies have adopted pollution and waste prevention programs that have led to cleaner production. Docsity.com 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. Docsity.com