Day 2 Sedimentary Petrology

Question 1

Physical destruction of the original rock

Answer 1

Mechanical weathering

Question 2

Loose deposits are converted into rocks through the processes of:

Answer 2

Diagenesis and Lithification

Question 3

Solid fragments and mineral particles from mechanical weathering

Answer 3

Detritus or clastic material

Question 4

Sediments with clastic textures

Answer 4

Terrigenous sediments

Question 5

Decomposes minerals in the rocks

Answer 5

Chemical weathering

Question 6

Greek, meaning correct or true. Truly chemical sediments which are products of chemical decomposition

Answer 6

Orthochemical sediments

Question 7

Greek, meaning different. Organisms have caused the precipitation of the major sedimentary mineral components, or the precipitated minerals have undergone substantial movement (and redeposition) after crystallization

Answer 7

Allochemical sediments

Question 8

Consists of detrital grains, which forms the framework of the rock, joined together by cement.

Answer 8

Terrigenous sedimentary rocks.

Question 9

Consists of large clasts (boulders, cobbles, pebbles, granules) with or without a sandy matrix

Answer 9

Conglomerates and breccias

Question 10

Show more pronounced rounding of clasts

Answer 10

Conglomerates

Question 11

Contain more angular clasts

Answer 11

Breccia

Question 12

Coarse-grained pyroclastics (volcanic debris) with a grain size over 32mm

Answer 12

Agglomerate or volcanic breccia

Question 13

Finer-grained (2 and 0.062 mm grain size) and most easily classified by determining the amounts of clastic (framework) grains composed of quartz (and chert), feldspar, and lithic fragments

Answer 13

Sandstones

Question 14

When the sandstone matrix contitutes more than 10 volume percent of the rock

Answer 14

Wacke

Question 15

Mostly dark gray sandstones with abundant matrix

Answer 15

Greywacke

Question 16

Sandstones made up of chiefly volcanic fragments, volcanic glass, and crystals. Tend to be green because of chlorite.

Answer 16

Volcaniclastics

Question 17

General term for sediments composed mainly of silt-sized (0.062 - 0.004 mm) and clay-sized (<0.004mm) particles

Answer 17

Mudstone

Question 18

Silt-particle size

Answer 18

Siltstones

Question 19

Clay particle size; nonfissile, commonly with a massive or blocky texture

Answer 19

Claystones

Question 20

Characterized by its fissility (ability to split into thin sheets), generally parallel to bedding

Answer 20

Shale

Question 21

With a well-developed cleavage, which may or may not be parallel to the bedding, and is commonly the result of metamorphism

Answer 21

Slate

Question 22

Emphasizes the depositional texture

Answer 22

Dunham’s Classification of Limestones

Question 23

Consists more than 10% grains in a microcrystalline ooze (micrite)

Answer 23

Wackestones

Question 24

Grain-supported limestone with micrite matrix and sparry calcite cement

Answer 24

Packstone

Question 25

Grain-supported limestone with very little micrite

Answer 25

Grainstone

Question 26

Equivalent to biolithite, a limestone made up or organic structures that grew in situ, forming rock mass during growth

Answer 26

Boundstone

Question 27

Formed by direct precipitation

Answer 27

Orthochemical sedimentary rocks

Question 28

Fine-grained poorly cemented; Soft and low density pure carbonate.

Answer 28

Chalk

Question 29

Calcite recrystallizes easily, and secondary dolomite, replaces the original calcium carbonate; often destroys the texture of original carbonate

Answer 29

Dolomitization

Question 30

A very fine-grained carbonate precipitate that has settled to the bottom of the basin

Answer 30

Microcrystalline ooze

Question 31

Coarser in grain size than the ooze and tends to be clear or translucent; a pre-filling cement that was precipitated in place

Answer 31

Sparry calcite cement

Question 32

Fragments of weakly consolidate carbonate sediment that have been torn up, transported, and redeposited by currents within the basin of deposition

Answer 32

Intraclasts

Question 33

In a size range of 0.1 to 1.0 mm in diameter, are spherical, show radial and concentric structures, and resemble fish roe. They are commonly formed by chemical accretions around nuclei such as shell fragments, pellets, or quartz sand grains.

Answer 33

Oolites

Question 34

Remains of organisms

Answer 34

Fossils

Question 35

Well-rounded, homogenous aggregates of microcrystalline calcite in a size range of 0.03 to 0.2 mm in diameter, feces of mollusks, worms, and crustaceans.

Answer 35

Pellets

Question 36

Consists of a matrix of allochemical constituents and sparry calcite cement

Answer 36

Type I (Folk’s Classification of Limestones)

Question 37

Variable percentage of allochemical grains in a microcrystalline matrix

Answer 37

Type 2 (Folk’s Classification of Limestones)

Question 38

Microcrystalline calcite matrix only (micrite)

Answer 38

Type 3