Midterm Study Guide 5

Question 1

What are the main distinctions for sedimentary rocks?

Answer 1

• Composed of particles of previously existing rock (usually sandstone), these particles are not always homogeneous, however. stratification is visible. the presence of fossils. more porous and less dense than other rock types. react to dilute acids.
• Clastic and Non Clastic
  - Clastic - Physical weathering and
  cementation or compaction to create
  rocks
  - Non-clastic - Chemical and biological
  weathering that later accretes into rocks

Question 2

Why are igneous rocks coarsely crystalline and extrusive ones finely?

Answer 2

Intrusive igneous rocks cool slowly, allowing their grains to form together, making them coarse. Extrusive igneous rocks are flash cooled, causing them to have small grains, making them fine.

Question 3

In which plate tectonic settings do you expect magma to form?

Answer 3

Environments include subduction zones, continental rift zones,[2] mid-ocean ridges and hot spots

Question 4

Why do melts migrate upward?

Answer 4

• Melts move upward because they are less dense than the solids.
• Less denser stuffs sink at the same time. the lighter ones go up.

Question 5

In which plate tectonic setting would you find regional metamorphism?

Answer 5

Continental

Question 6

What are Steno’s laws?

Answer 6

• Principle of Superposition: In a sequence of
  undisturbed layered rocks, the oldest rocks are
  on the bottom
• Principle of Original Horizontality: Layered strata
  are deposited horizontally or nearly horizontally
  and nearly parallel to Earth’s surface
• Principle of Lateral Continuity (cross cutting
  relationship): Layered rocks are deposited in
  continuous lateral contact

Question 7

What are cross-cutting relationships?

Answer 7

States that the geologic feature that cuts another is the younger of the two features. Cross-cutting relations can be used to determine the relative ages of rock strata and other geological structures.

Question 8

sedimentary rock

Answer 8

made up of material derived from the breakdown of preexisting rocks. Rocks expose to water and air at the earth surface including chemical or physical break down, destroying some mineral and create new ones (ex: sand, clay and silt are compressed and become solid rock).

Question 9

mineral

Answer 9

the building blocks of rocks.

Question 10

intrusive

Answer 10

something occurring inside ex- intrusive igneous rocks

Question 11

clay

Answer 11

compressed into shale

Question 12

basalt

Answer 12

is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon.

cools quickly

Question 13

sandstone

Answer 13

is a clastic sedimentary rock composed mainly of sand-sized minerals or rock grains.
Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth’s crust.

Question 14

foliation

Answer 14

repetitive layering in metamorphic rocks that can be thin or thick. (ex - mica)
schist

Question 15

igneous rock

Answer 15

hot molten magma which erupted as volcanoes and associated lava flows on the earth’s surface, or as intrusive magma chamber which cooled far below the earth surface

Question 16

metamorphic grade

Answer 16

(low-grade) shale -> slate -> schist -> gneiss (high-grade)

Question 17

grain size

Answer 17

grain size growth depends on the cooling time. Longer molten state means larger grains.

Question 18

pluton

Answer 18

intrusive igneous rock that is crystallized from magma slowly cooling. Cooled batholiths (large widespread magma chambers)..

Question 19

limestone

Answer 19

the most abundant non clastic sedimentary rocks, which precipitated from chemical solutions and/ or accumulated chemical, biological matter (crystalline, massive, skeletal)

Question 20

marble

Answer 20

metamorphic rock from limestone

Question 21

shale

Answer 21

the most abundant clastic rocks (compacted and cemented from detrital sediments)

Question 22

gneiss

Answer 22

(high grade metamorphic)

Question 23

metamorphic rock

Answer 23

has changed their form under influence of heat , pressure and fluid, preexisting rocks are modified to produce new one (differentiate from sedimentary rocks is change in the solid state, no melting)

Question 24

extrusive

Answer 24

formed above the earth’s surface

Question 25

continental shelf

Answer 25

the extended perimeter of each continent associated with a coastal plain. Submerged under relatively shallow seas. In the presence of a subduction zone next to an oceanic-continental convergence, there might not be a shelf.

Question 26

Decompression melting

Answer 26

A decrease in pressure, just as a rise in temperature, can melt materials, specifically rocks in this case. Therefore, decompression melting takes place as a result of less pressure being exerted on rocks. This occurrence is common at mid-ocean ridges where rocks are uplifted and consequently have less overburden.

Question 27

granite

Answer 27

Is a common type of intrusive, felsic, igneous rock which is granular and phaneritic in texture. This rock consists mainly of quartz, mica, and feldspar.

Question 28

diagenesis

Answer 28

physical/chemical processes of turning sediments into sedimentary rocks. Physical means: uses the process of lithification (compacting/cementing the sedments) to turn them to rocks.

Question 29

orogeny

Answer 29

process by which earth’s crust is folded and deformed by lateral compression to form a mountain range