Week 5 Sedimentary Rocks

What is a sediment

The transported product of physical disintegration and chemical decomposition of older rock

Sedimentary Rock

The product of lithification of sediment by means of compaction and/or cementation

Siliciclastic

deposition by water, wind, or ice

Chemical

precipitation from solution

Biogenic

Growth in position by organic processes

What are the four 4 stages of forming a sedimentary rock?

weathering, transport, deposition, lithification

Siliciclastic sediments

predominantly made from the broken-down pieces of pre-existing rock

What are conglomerates and breccias

sedimentary rocks composed of clasts

What is the difference between conglomerates and breccias

conglomerates have rounded clasts while breccias have angular clasts

What are sandstones with mud called?

Greywacke

Sandstones mostly made of quartz are called

quartz arenite

What is shale 

usually refers to very fine-grained siliciclastic rocks made of sediments from marine settings

What are Volcaniclastics

10% or greater extrusive volcanic materials

Chemical sediments

precipitate from a solution usually due to oversaturation of ions

Chemical chert

made of microcrystalline quartz that precipitates from ocean water

Oolitic limestone

made when ocean water becomes supersaturated in carbonate ions and precipitates due to shoaling swash action to form ooids

Biogenic sediments

inorganic but are made by biological processes

Fossiliferous limestones

composed of fossil shells, corals, and other carbonate materials

Coquinas

consists of sand and/or gravel sized particles of shell fragments and other carbonate material

Chalk

made of the microscopic carbonate remains of plankton that fall to the seafloor forming calcareous ooze

Biogenic chert

siliceous remains of plankton that fall to the seafloor

Exfoliation

Due to pressure release as deeply buried rocks reach the surface due to removal of overlying material

Frost and Salt Wedging

Repeated freezing/thawing of ice expanding cracks in rocks

Abrasion

Physical interaction of materials due to external forces causing macro- and micro- breakages

Insolation

Expansion and contraction of rocks that are heated by the sun and cool down at night

Dissolution

Ions disassociate releasing into the groundwater

Oxidation

Oxygen dissolved in water reacts with with iron-bearing silicate minerals

Hydrolysis

Chemical reaction between mineral ions and ions of water

Duricrusts

major accumulations of less mobile elements in stable minerals, product of weathering

Chelation

Bonding of mineral cations and organic molecules produced by plants