6 Metamorphic Rocks – An Introduction to Geology. Contributing Author: Dr. Peter Davis, Pacific Lutheran University Describe the temperature and pressure conditions of the metamorphic environmentIdentify and describe the three principal metamorphic agentsDescribe what recrystallization is and how it affects mineral crystalsExplain what foliation is and how it results from directed pressure and recrystallizationExplain the relationships among slate, phyllite, schist, and gneiss in terms of metamorphic gradeDefine index mineralExplain how metamorphic facies relate to plate tectonic processesDescribe what a contact aureole is and how contact metamorphism affects surrounding rockDescribe the role of hydrothermal metamorphism in forming mineral deposits and ore bodies Metamorphic rocks, meta- meaning change and –morphos meaning form, is one of the three rock categories in the rock cycle (see Chapter 1). 6.1.1 Temperature (Heat) Temperature measures a substance’s energy—an increase in temperature represents an increase in energy . 6.1.3 Fluids.
Properties of Minerals | Earth Science | Visionlearning. Geologists have recently determined that the minerals goethite and hematite exist in abundance on Mars, sure signs of the presence of water (see Figure 1 for a picture). None of those geologists have been to Mars, of course, but the unmanned rovers Spirit and Opportunity have. These rovers are equipped with three mass spectrometers, each of which is capable of determining the chemical composition of a solid with a high degree of accuracy. With such a precise chemical analysis in hand, geologists on Earth had no problem identifying the minerals. A mineral is defined in part by a specific chemical composition. In theory, therefore, it is always easy to identify a mineral, if you can determine the chemical composition with a mass spectrometer like the Mars rovers.
The most common minerals in Earth's crust can often be identified in the field using basic physical properties such as color, shape, and hardness. Comprehension Checkpoint The context in which a mineral is found Color Crystal form. Sedimentary Rocks | USGS Schoolyard Geology. ...until you stop moving the pieces. Once the sediment stops being transported, you have a bunch of pieces of sediment in one place.
A pile of sand is an example; you might find such a pile at a sandbar along the edge of a river. You can also find sediment that has been deposited at the bottom of steep hills, at the beach, in sand dunes, and many other places on earth. Larger pieces are harder to transport, so they tend to stop moving (deposition) before smaller pieces. You can try this in the classroom -- throw a scoop of sand and soil into a glass bottle. Rock Key. The Rock Identification Key - by Don PeckRock Key Table of Contents What Are Rocks?
Rocks are what the crust of the earth is made of. They are the mountains and the bottom of the ocean. They are everywhere on earth, but often buried under soil. Rocks are made of minerals, like quartz, calcite, feldspars, and micas. Most rocks are made from more than one mineral, but there are quite a few kinds that are made from only one mineral. Minerals are not rocks, rocks are made of minerals. A car is made of steel, glass, and plastic. . [ Return to Rock Key Table of Contents ] What Minerals Form Rocks? Earth Materials Outline. Making Ramen All we have to work with in sustaining our world: Earth’s Raw Materials 1. Composition of the Continental Crust O- Oxygen 47% Si- Silicon 28% These together = 75% of continental crust...
Al - Aluminum 8.1% Fe - Iron 5.0% Ca - Calcium 3.6% - nutrient Na - Sodium 2.8% - nutrient K - Potassium 2.6% - nutrient Mg - Magnesium 2.1% - nutrient 2. A. B. Felsic: lighter minerals with more Si (silicon); dominates in continental crust (SIAL) Mafic: dark minerals with Mg (magnesium) and Fe (iron); dominates in ocean crust (SIMA) C. O Silicates: have Si as base, Quartz (SiO2) = 75% o Aluminosilicates: have Si and Al, and when add (Ca, K, Na), you get Feldspars o Clay minerals: stick to your shoes and have tetrahedral structures: D.
O Typical Morning: how you use minerals/elements o Pretty things to collect as Gemstones or Mantle Pieces: o Crystal Daze, Story of a 2001 Darwin Award Winner 3. Each one of these represents a different class in geology, studied for its own sake... 4. 5. O Examples: Geology - rocks and minerals. Igneous rocks are formed by the solidification of magma, a silicate liquid generated by partial melting of the upper mantle or the lower crust. Different environments of formation, and the cooling rates associated with these, create very different textures and define the two major groupings within igneous rocks: Volcanic rocksVolcanic rocks form when magma rises to the surface and erupts, either as lava or pyroclastic material. The rate of cooling of the magma is rapid, and crystal growth is inhibited.
Volcanic rocks are characteristically fine-grained. Volcanic rocks often exhibit structures caused by their eruption, e.g. flow banding (formed by shearing of the lava as it flows), and vesicles (open cavities that represent escaped gasses). Plutonic rocksPlutonic rocks form when magma cools within the Earth's crust. Textures of igneous rocks The environment of formation produces characteristic textures in igneous rocks which aid in their identification. Other features. Documents utiles aux Géologues. VHP Photo Glossary: Volcanic rocks. An igneous rock is formed by the cooling and crystallization of molten rock. The term igneous is derived from ignius, the Latin word for fire. Scientists have divided igneous rocks into two broad categories based on where the molten rock solidified. Volcanic rocks (also called extrusive igneous rocks) include all the products resulting from eruptions of lava (flows and fragmented debris called pyroclasts).
Plutonic rocks (also called intrusive igneous rocks) are those that have solidified below ground; plutonic comes from Pluto, the Greek god of the underworld. The initial distinction between volcanic and plutonic rocks is made on the basis of texture (fine-grained volcanic vs. coarse-grained plutonic). Volcanic and plutonic rocks are divided further on the basis of chemistry and mineral composition. These rock types all have different characteristics, including temperature when fluid, viscosity (resistance to flow), composition, explosiveness, and types, amounts, and sizes of minerals. Brooklyn College - Core 3.32 - Geology. Metamorphic Rocks Metamorphic rocks are the result of the transformation of a pre-existing rock type, the protolith, in a process called metamorphism, which means "change in form ".The protolith is subjected to heat and pressure (temperatures greater than 150 to 200 °C and pressures of 1500 bars) causing profound physical and/or chemical change.
The protolith may be sedimentary rock, igneous rock or another older metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and are classified by texture and by chemical and mineral assemblage (metamorphic facies). They may be formed simply by being deep beneath the Earth's surface, subjected to high temperatures and the great pressure of the rock layers above. They can be formed by tectonic processes such as continental collisions which cause horizontal pressure, friction and distortion. They are also formed when rock is heated up by the intrusion of hot molten rock called magma from the Earth's interior. STRATA Terminology. Sediment deposition and reworking associated with storms (tempestites) and turbidite currents (turbidites) are unpredictable, sudden, and catastrophic.
Both experience many of the same processes, have similar character and so are difficult to distinguish from each other. Tempestites are the products of storms that produce waves and currents that extend to and just below wave base in shallow shelf settings. In contrast turbidites are the products of the suddent mobilization of sediment on the shelf margin by the sediment surface over-steepening on the sea floor and sudden movement downslope triggered potentially by too much sediment, storms and/or earthquakes. Both tempestites and turbidites are the products of events that are "aperiodic" and of varying magnitudes, the larger the more rare. The larger events wipe out the signatures of earlier smaller ones. The table and attached diagram below suggest strategies for separating tempestite deposits from those of turbidites. Sedimentary Processes and Structures.
Of the variety of transport mechanisms discussed, sedimentologic evidence from the Trenton Limestone suggests that a variety of storm-influenced, gravity influenced, and suspension settling transport mechanisms were active in the accumulation of these carbonates. >>Back to Top Mud Transport in the Trenton: According to studies by Titus (1974) and Mehrtens (1988, 1992), aside from purely micritic beds with nearly 100% micritic mud, nearly all coarser-grained limestone beds in the Trenton are composed of between 10 and 50% micritic mud. Some of this micritic mud was potentially produced in the shallowest settings locally on the Trenton Shelf, but it is unlikely that the entire micritic mud budget is locally derived. Pelletal and flocculated muds were both transported as components of down-slope transport processes, either storm-generated or gravity generated, as well as through suspension settling processes as evidence by beds deposited during background sedimentation.
Sedimentary rocks (PowerPoint) Sedimentary depositional environment. Sedimentary depositional environment In geology, sedimentary depositional environment describes the combination of physical, chemical and biological processes associated with the deposition of a particular type of sediment and, therefore, the rock types that will be formed after lithification, if the sediment is preserved in the rock record. In most cases the environments associated with particular rock types or associations of rock types can be matched to existing analogues. However, the further back in geological time sediments were deposited, the more likely that direct modern analogues are not available (e.g. banded iron formations). Types of depositional environment Continental Transitional Marine Shallow water marine environmentDeep water marine environmentReef Others Recognition of depositional environments in ancient sediments References Harold G.
External links Wikimedia Foundation. 2010. Look at other dictionaries: Eolianite — Holocene eolianite on Long Island, Bahamas. OzCoasts Conceptual model: Aquatic sediments (changed from natural) model. Our current best conceptual understanding of the stressor 'aquatic sediments' is shown in Figure 1. Figure 1. Potential causes of a change to aquatic sediments and the condition responses observed as a result of this change.
The introduction of both fine and coarse sediments into aquatic systems is an important natural process and is integral to the natural functioning of these systems. However, human induced increases in the natural loads of sediments, and most particularly fine sediments (<63 µm) entering systems can have a number of undesirable impacts. Within an estuary, fine sediments can remain in suspension, they may be deposited in low energy areas such as mangroves, forming muddy deposits, or are transported out of the estuary via tidal currents and are deposited in nearshore coastal areas. More information on this stressor. Course: Geology AS 2: Rocks. Geology Cafe.com. Essential concepts of chemistry related to earth materials Basic concepts of chemistry are essential to understanding the physical and chemical properties of earth materials (minerals, rocks, organic matter, etc.).
The chemical characteristics of earth materials are reflect the environments how and where they are formed, they also determine their potential fate when exposed to chemical changes. For instance, rocks and minerals formed deep underground may not be stable in the surface environment where they are exposed to water, air, temperature changes, and other physical and chemical conditions. All matter is made up of atoms, and atoms are made up of atomic particles (electrons, protons, and neutrons - see Figure 2-5). A chemical element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Common examples of elements are iron, copper, silver, gold, hydrogen, carbon, nitrogen, and oxygen.
Rocks 2.5. Classification of Metamorphic Rocks (Part 4) Composition • Common minerals in metamorphic rocks include quartz, feldspar, mica, calcite, and hornblende. • Index minerals in metamorphic rocks indicate how much the original rock was metamorphosed, called the grade of metamorphism. Index Minerals minerals include chlorite, epidote, garnet, staurolite, kyanite and sillimanite. Fine-grained crystals of chlorite (not visible) give this slate its green color. Chlorite is a complex silicate mineral formed during low-grade metamorphism. Slate (Photograph by Parvinder Sethi) Green crystals of epidote are visible in this sample of unakite.
Unakite (Photograph by Parvinder Sethi) The Rock Cycle. There are three kinds of rocks; each is formed a different way. Igneous rock forms from magma. Igneous means "from fire. " Deep beneath the surface of the earth it is so hot that rocks melt. This melted rock is called magma. When magma reaches the surface of the earth through volcanoes or cracks in the earth's crust, it is called lava. Sedimentary rock forms from sediment. Metamorphic rock forms from other rock. Click on the player below to watch a video on how the different types of rocks are formed... Now click on each of the red boxes below to learn more about each type of rock... Geology - rocks and minerals.