CH.6

25 July 2022
4.7 (114 reviews)
53 test answers

Unlock all answers in this set

Unlock answers (49)
question
________, a common mineral found in igneous rocks, is the most abundant mineral in detrital sedimentary rocks.
answer
Quartz
question
Which major component of detrital sedimentary rocks only rarely occurs as a primary mineral in igneous rocks?
answer
clays
question
________ cement produces bright-red and yellow colors in some sandstone.
answer
Iron oxide
question
Studies of deep-sea sediment cores have contributed greatly to scientific knowledge of ________.
answer
climatic changes during the last four million years
question
Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks?
answer
evaporate minerals are more soluble than calcite and quartz
question
Which statement concerning sedimentary rocks is not true?
answer
they were originally deposited at depth below the bottom of the sea
question
Which of the following applies to the basic constituents of halite, gypsum, and sylvite?
answer
transported as dissolved ions; deposited by evaporation
question
Sedimentary rocks account for about what percentage of the Earth's outermost 10 kilometers of rock (first percentage). Also, what percentage of the Earth's continental area is covered by sedimentary rocks (second percentage)?
answer
5% & 75%
question
Detrital grains of which mineral(s) are extremely rare in detrital sediments? Why?
answer
calcite; it is soft and relatively soluble
question
What is the chemical formula for dolomite, the major mineral in dolostones?
answer
CaMg(CO3)2
question
Zircon and tourmaline are dense, highly insoluble, chemically stable, minor minerals of igneous and metamorphic rocks. In which sedimentary rock might you expect to find these minerals concentrated?
answer
sandstone lithified from quartz-rich beach sand
question
Compaction is a very important part of the lithification process for which of the following sediments?
answer
mud
question
mud
answer
silica; calcite
question
Which of the following best describes bedded gypsum and halite?
answer
evaporates; chemical, sedimentary rocks
question
________ sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion of granitic bedrock.
answer
Arkosic
question
________ cement produces bright-red and yellow colors in some sandstone.
answer
Iron oxide
question
What is probably the single most important, original, depositional feature in sedimentary rocks?
answer
bedding or stratification
question
Which of the following would retain the most detailed impressions of fossilized organisms?
answer
very fine-grained volcanic ash deposited in an ancient lake
question
What is a bittern?
answer
residual brine left after precipitation of halite
question
________ are further concentrated in a residual brine after NaCl is crystallized.
answer
Potassium, magnesium, and bromine
question
Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks?
answer
evaporate minerals are more soluble than calcite and quartz
question
What is the main difference between a conglomerate and a sedimentary breccia?
answer
breccia clasts are angular; conglomerate clasts are rounded
question
A graywacke is ________.
answer
a sandstone with the sand grains embedded in a clay-rich matrix
question
Which type of limestone consists mainly of tiny, marine fossils composed of calcite?
answer
chalk
question
________ is not a common cementing agent for sandstones.
answer
Fluorite
question
Detrital sedimentary rocks are classified (named) based on the ________.
answer
grain sizes of the detrital particles
question
Flint, chert, and jasper are microcrystalline forms of ________.
answer
quartz; (SiO2)
question
Which of the following sedimentary rocks would you expect to have originally been deposited by fast-moving streams?
answer
conglomerate
question
Which type of sediment undergoes the most compaction as it lithifies to sedimentary rocks?
answer
marine mud
question
Which of the following sedimentary features would typically be found in shales but not in sandstones?
answer
mud cracks
question
________ is the most common type of chemical sedimentary rock.
answer
Limestone
question
________ is a form of calcium carbonate.
answer
Travertine
question
Which one of the following is not a chemical sedimentary rock or evaporite?
answer
shale
question
Which of the following is not a type of limestone?
answer
arkose
question
Oolitic limestone is most likely to form in what type of depositional environment?
answer
shallow, clear, marine waters with vigorous current activity
question
Which of the following sedimentary features can each be used to determine paleocurrent directions?
answer
ripple marks and cross stratification
question
Coal beds originate in ________.
answer
freshwater coastal swamps and bogs
question
Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas?
answer
high porosity
question
Nonclastic textures are common in which of the following sedimentary rocks?
answer
limestones
question
Clay and muddy sediments lithify to form shales and mudstones.
answer
True
question
Detrital sedimentary rocks have clastic textures.
answer
True
question
Peat is thought to be the original material from which coals are formed.
answer
True
question
Graywacke sandstones are typically better sorted than sandstones lithified from ancient beach sands.
answer
False
question
Clastic particles in a sedimentary breccia are rounded and are about the same size as fine-grained sand.
answer
False
question
Many limestones are of biochemical origin.
answer
True
question
Boulder conglomerates suggest deposition by strong winds in a desert.
answer
False
question
Mud cracks in a shale or mudstone indicate that the mud or clay was deposited in deep waters of an offshore marine environment.
answer
False
question
Chalk, coquina, and ancient coral reefs are primarily composed of microcrystalline quartz.
answer
False
question
Water is gradually expelled from compacting clay and mud sediments.
answer
True
question
The mineral dolomite, which is the major mineral of the sedimentary rock dolostone, is a carbonate of calcium and magnesium.
answer
True
question
tThe chemical sedimentary rock, conglomerate, is composed of gravel-size, rounded, calcite oolites.
answer
False
question
Detrital sedimentary rocks are classified according to clastic particle size; chemical sedimentary rocks are named according to the most abundant minerals.
answer
True
question
A feldspar-rich sandstone is called an arkose.
answer
True