Ch7 Flashcards
What us probably the single most important, original, depositional feature in sedimentary rocks
Bedding or stratification
Flint, chert, and jasper are microcrystalline forms of
Quartz
A graywacke is
A sandstone with sand grains embedded in a clay rich matrix
Which of the following applies to the basic constituents of halite, gypsum, and sylvite
Transported as dissolved ions; deposited by evaporation
Compaction is a very important part of lithification process for which of the folllowing sediments?
Mud
Which characteristic is absolutely necessary for a sedimentary rock to have potential as a possible reservoir rock for oil or gas
High porosity
A cherty limestone would contain which major constituents
Silica; calcite
____ cement produces bright red and yellow colors on some sandstone
Iron oxide
Studies of deep sea sediment views have contributed greatly to scientific knowledge of
Climatic changes during the last four million years
Which of the following sedimentary features would typically be found in shales but not in sandstones?
Mud cracks
Detrital sedimentary rocks are classified based on the
Grain sizes of the detrital particles
Which of the following is not a type of limestone
Arkose
____ a common mineral found in igneous rocks, is the most abundant mineral in detrital sedimentary rocks
Quartz
Which of the folllowing sedimentary features can each be used to determine paleocurrent directions
Ripple marks and cross stratification
Oolitic limestone is most likely to form in what type of depositional environment
Shallow, clear, marine waters with vigorous current activity
Which of the following describes the correct order for relative solubility of minerals in sedimentary rocks
Evaporate minerals are more soluble than calcite and quartz
Which type if limestone consists mainly of tiny, marine fossils composed of calcite
Chalk
___ sandstone contains abundant feldspar, suggesting that the sand was derived by weathering and erosion if granitic bedrock
Arkosic
Which of the following best describes bedding gypsum and halite
Evaporates, chemical, sedimentary rocks
Sedimentary rocks account for about what percentage of the earths outermost 10km
5%
What percentage of the earths continental area is covered by sedimentary rocks
75
Coal beds originate in
Freshwater coastal swamps and bogs
___ is a form a calcium carbonate
Travertine
Which of the following sedimentary rocks would you expect to have orginally been deposited by fast moving streams
Conglomerate
What is the main difference between conglomerate and breccia
Breccia clasts are angular, conglomerate clasts are rounded
___ is not a common cementing aging for sandstone
Fluorite
Boulder conglomerates suggest deposition by strong winds in a desert
False
Chalk, coquina, and ancient coral reefs are primarily composed of microcrystalline quartz
False
Clay and muddy sediments lithify to form shales and mudstones
True
Detrital sedimentary rocks are classified according to clastic particle size; chemical sedimentary rocks are named according to the most abundant minerals
True
Graywacke sandstones are typically better sorted than sandstones lithified from ancient beach sand
False
Many limestones are biochemical in origin
True
Mud cracks in a shake or mudstone indicate that the mud or clay was deposited in feels waters if an offshore marine environment
False
Peat is thought to be the original material from which coal is formed
True
The mineral dolomite, which is the major mineral of the sedimentary rock dolostone, is a carbonate of rich calcium and magnesium
True
Water is gradually expelled from compacting clay and mud sediments
True
