Module 11 Assignment

What are the two most important driving forces of metamorphism? Weathering and accumulation High heat and pressure Melting and crystallization Magma and lava Deposition and lithification

High heat and pressure

When lava erupts at Earth's surface, what type of rock is produced? intrusive limestone extrusive metamorphic sedimentary

extrusive

Basaltic igneous rocks contain which of the following minerals: potassium feldspar and quartz. olivine and quartz. pyroxene and calcium-rich plagioclase feldspar. amphibole and intermediate plagioclase feldspar. olivine and pyroxene.

pyroxene and calcium-rich plagioclase feldspar.

What is a fine-grained igneous rock composed primarily of very small crystals of potassium feldspar and a few large crystals of quartz? granite porphyry basalt porphyry komatiite porphyry andesite porphyry rhyolite porphyry

rhyolite porphyry

Which of the following types of lava will most likely lead to a volcanic eruption of an effusive nature? basaltic andesitic rhyolitic

rhyolitic

Which of the following types of magma has the highest viscosity? andesitic basaltic rhyolitic

rhyolitic

As a result of partial melting, magma originates in __________. the mantle and crust the outer core and the inner core the crust and the inner core the outer core and the mantle the atmosphere

the mantle and crust

In what type of igneous feature would you find rocks with a vesicular texture? laccolith sill the surface of a lava flow at the base of a lava flow batholith

the surface of a lava flow

Pyroclastic debris from a volcanic eruption can include _____. cross-bedding coarse-grained crystals ash and cinders very well-rounded particles fossils

ash and cinders

Which of the following igneous rocks contains no mineral crystals? gneiss basalt obsidian limestone granite

obsidian

What is a coarse-grained rock composed of intermediate plagioclase feldspar and pyroxene? peridotite gabbro granite andesite diorite

diorite

An igneous rock that contains quartz and potassium feldspar would have a mineralogic content placing it in the range of __________. andesitic or intermediate rocks glassy rocks ultramafic rocks basaltic or mafic rocks granitic or felsic rocks

granitic or felsic rocks

What are the two important processes involved in lithification of sedimentary rocks? Cementation and compaction Cooling and reorganization Crystallization and uplift Transportation and accumulation

Cementation and compaction

An igneous rock becomes buried, is subject to high heat and pressure, and recrystallizes. This rock then is eroded, transported, deposited and subsequently lithified. Which rock types—in order—did the original igneous rock develop into? Metamorphic and igneous Sedimentary and metamorphic Igneous and sedimentary Metamorphic and sedimentary

Metamorphic and sedimentary

What process forms igneous rocks? compaction of sediments alteration of sediments by heat and pressure deposition of sediments weathering and transport of magma cooling and solidification of magma

cooling and solidification of magma

Which of the following agents move sediment from one place to another? CHOOSE ALL THAT APPLY. wind convection cells glaciers volcanoes rivers

wind glaciers rivers

Consider this brief review of some of the most typical features of each major rock type: Igneous rocks are solidified magma that possess interlocking crystals of varying sizes (from visible to too small to see) and that possess a range of textures. Sedimentary rocks tend to be layered deposits of transported material fragments (from clay to boulder-sized) with varying degrees of sphericity (rounding) and sorting. They may also include some structures such as cross-beds. Metamorphic rocks often have elongated or differential stress-changed mineral foliations (their preferred orientation). Metamorphic rocks also possess the full range of grain sizes, from very fine to very coarse. After exploring the Gigapan image, arrange the following observations and inferences by their respective rock unit. These observations and inferences describe the material, appearance, and weathering pattern of the respective rock units. Drag the appropriate items to their respective bins. Each item may be used only once.

Rock Unit #1 Appears to be massive (few, thick layers) Black and dark gray in color Weathers into blocky pieces Crystals too small to see Rock Unit #2 Red and white in color Appears to have many thin layers Sediments too small to see Weathers into small irregular shapes

As a geologist, you always want to first locate your field site on a map. It helps other geologists to locate the field site for future studies and helps you look for relationships with data from nearby field sites. Determine where you are (your field site) in the world. Choose the map that best locates your field site.

The outcrop is located in the northeast corner of Minnesota. Take a moment to reflect on what you know about this area already. Is it an active plate boundary? Does it have mountains, volcanoes, glaciers, etc?

Most igneous rocks never reach the surface. However, igneous rocks other than those formed in volcanoes are found exposed on many parts of Earth. How do you account for this phenomenon? They are the result of meteorite impact. They formed at depth and have been exposed by uplift and erosion. They have been glaciated. They are composed of lava flows. They formed at the surface and sank due to their greater density.

They formed at depth and have been exposed by uplift and erosion.

Choose the cross-section sketch that best represents the rock units you observe at this scale.

You have come to see that there are two main rock units stacked on one another. Next you will interpret the type of environment where this rock formed. Understanding the rock unit features in an outcrop can be important in order to develop some interpretation for how it formed. Next you will interpret the type of environment where this rock formed.

While working in the field, you discover an outcrop of metamorphic rocks. What can you conclude from this observation? View Available Hint(s) You conclude that these rocks were deposited in a glacial moraine. You determine that these rocks formed in a volcano. You are certain that these rocks have undergone cementation and compaction. You know that these rocks formed near the surface of Earth. You know that these rocks formed at great depth below the surface.

You know that these rocks formed at great depth below the surface.

In addition to viscosity, which of the following parameters has an influence on whether a volcanic eruption will be effusive or violent? temperature of the magma amount of gas in the magma the depth of the magma chamber the slope of the volcanic cone how fast the lava cools

amount of gas in the magma

A geologist sends you a sample that was collected in the field. You find that it is a gray-colored igneous rock containing amphibole and intermediate plagioclase feldspar. Using Bowen's Reaction Series as a guide, how would you describe its composition? andesitic basaltic granitic This combination can't occur in nature. ultramafic

andesitic

What is the term used to describe a very large, widespread, and deep intrusive body of igneous rock? laccolith batholith sill lava flow volcano

batholith

What is the classification of igneous rocks based on? composition and texture color and composition the presence or absence of foliation porosity and permeability grain size and texture

composition and texture

What element is principally responsible for making olivine, pyroxene, amphibole, and biotite dark? potassium calcium iron sodium manganese

iron

Basalt is an igneous rock that can be identified by its small crystals. What are they composed of? olivine and pyroxene pyroxene and calcium-rich plagioclase feldspar olivine and quartz quartz and potassium feldspar amphibole and intermediate plagioclase feldspar

pyroxene and calcium-rich plagioclase feldspar

Most igneous rocks are primarily composed of: View Available Hint(s) carbonate minerals. silicate minerals. oxide minerals. sulfide minerals. sulfate minerals.

silicate minerals.

Can you determine what types of igneous rock share the same mineral composition, but are different in texture, and are therefore different rocks? Drag the appropriate labels to their respective targets.

Granitic - Rhyolite Andesitic - Diorite Basaltic - Gabbro Ultramafic - Peridotite

_____ igneous rocks are those that cool below the surface. Extrusive Volcanic Intrusive Basaltic Vesicular

Intrusive

Why does magma have a tendency to rise after its formation? It is denser than the surrounding rock. The rocks below can't melt. It has less volume when it is a liquid. It contains significant amounts of volatile gases. It is less dense than the surrounding rock.

It is less dense than the surrounding rock.

What is the difference between magma and lava? Magma cools to produce extrusive igneous rocks; lava cools to produce intrusive igneous rocks. Magma is molten rock located above the surface; lava is molten rock below ground. Magma is lower in temperature; lava is higher in temperature. Magma is molten rock located below the surface; lava is molten rock erupted above ground. Magma is generally granitic in composition; lava is dominantly basaltic in composition.

Magma is molten rock located below the surface; lava is molten rock erupted above ground.

Geologists collect observations from field sites and then summarize their interpretations. One of the ways they do this is to consider the order of events chronologically. They take information from their observations and then apply the fundamental aspects of geology to tell the story. Now you can apply what you learned about this outcrop to consider the geologic episodes that lead to its formation. Arrange the following geologic episodes in the order that they occurred. The first step is recognizing what episodes relate to what bedrock units. Then, consider the order in which episodes occurred by the position (elevation) in the outcrop. Rank each process from oldest to youngest/most recent.

Oldest Deposition of sediments on a floodplain Compaction and cementation of sediments (lithification) A nearby volcano erupts, creating a lava flow Youngest/Most Recent Lava flow erodes sedimentary layers and then cools on top of them

Metamorphic rocks can form when which of the following conditions are met? Pre-existing rocks undergo metamorphism when they are subjected to heat and pressure without melting. As pre-existing rocks undergo crystallization, the result is metamorphic rock. When pre-existing rocks melt, they are transformed into metamorphic rocks. Pre-existing rocks can undergo metamorphism when they are subjected to repeated freezing and thawing. The presence of fossils in pre-existing rocks leads to the development of metamorphic rocks.

Pre-existing rocks undergo metamorphism when they are subjected to heat and pressure without melting.

Geologists develop an understanding of the geologic history of an outcrop by considering rock type, mineral composition, and the type of environment in which rock units formed. Some key ideas to keep in mind include the following: Sedimentary rocks are often well layered, and those formed on land are often oxidized (e.g., red in color) due to weathering in an oxygen-rich environment. Igneous rocks crystallize from magma at fast rates on the surface and slower rates in the subsurface, producing tiny and large mineral crystals, respectively. The compositional spectrum of igneous rocks is fundamentally determined by the silica content. Basalts and gabbros are low silica and dark in color, compared to rhyolite and granite, which are high in silica and lighter in color. Look at the types of characteristics listed below, and then assign them to their respective rock unit. Some characteristics will fall within one rock unit or the other. All characteristics will fall within one of the two rock unit categories. Drag the appropriate items to their respective bins. Each item may be used only once and some items may not be used at all.

Rock Unit #1 Igneous rock Formed by lava cooling and crystallizing on the surface Basalt Rock with a low-silica content Rock Unit #2 Sedimentary rock Mudstone Deposited in a terrestrial environment

Now that you've identified the rock types present (basalt and mudstone) and started to interpret how they formed in the past (cooled lava flow and old soils and sediments), let's reflect on the timing of the formation of each rock unit. Based on what you know about the law of superposition, which rock unit is older and formed first? They are the same age and formed at the same time. Rock unit #1 Rock unit #2

Rock Unit #2

The formation of sedimentary rocks occurs under what conditions? Sedimentary rocks form when weathered particles are cemented and/or compacted. When weathered particles are subjected to extreme heat and pressure, the result is sedimentary rock. If weathered particles are heated to the point where they melt, the result is sedimentary rock. When sediments are carried deep within Earth's crust, sedimentary rocks can form. Sedimentary rocks form during the assimilation of weathered particles into magma.

Sedimentary rocks form when weathered particles are cemented and/or compacted.

Rock units tell us about Earth's past. If we find evidence of geologic processes that have directional components (direction of plate movement, folds and faults, mineral foliation, wind and water currents, etc.), we need to be able to accurately reconstruct those directions. In terms of the scientific method, documenting outcrop orientation helps other geologists recreate the field investigation step-by-step to confirm or refute previous findings and associated interpretations. Choose the most accurate representation of the outcrop's orientation given your vantage point (as viewed using the Gigapan in relation to the outcrop).

The photographer/image is looking towards the west. In other words, the outcrop faces east at the lake behind the photographer.

Working in the field, you see a thin, dark-colored igneous sill across the valley. Without seeing the sill up close, what texture would you expect it to possess? poorly cemented coarse-grained fine-grained intrusive vesicular

fine-grained