Minerals & Weathering (origins of sediment)

Question 1

What is Bowen’s Reaction Series?

Answer 1

If we look at the major rock forming minerals, this is the order in which they form

Question 2

What is the order for Bowen’s reaction series?

Answer 2

1. Olivine, calcium-rich feldspar
2. pyroxenes, amphiboles, sodium-rich feldspar
3. biotite mica, muscovite mica, potassium-feldspar, quartz

Question 3

What is the order dependent on?

Answer 3

temperatures

Question 4

How do these minerals form?

Answer 4

1. deep in the earth with a melt/magma/liquid
2. they crystalize as the cool off

Question 5

What is the temperature range?

Answer 5

1000-600 centigrade

Question 6

What do the temperatures mean for the minerals?

Answer 6

600- in balance with the conditions at the surface
1000- out of wack

Question 7

(Bowen’s reaction series) What kind of rocks are formed?

Answer 7

• basalts: olivine, pyroxenes, dark in color, coming out of Hawaii
• -

Question 8

Which will weather first?

Answer 8

backwards in the sense that the mineral that is formed first goes first

Question 9

Are all beaches made of quartz?

Answer 9

no, coquina beaches are composed of coral, shells, and pellets (fecal matter)

Question 10

What are the two kinds of sand factories?

Answer 10

1. land: clastic sediment (decomposed rock)
2. ocean: (bio)chemical sediment- biologic material that gets broken up

Question 11

In the (bio)chemical process, which mineral is involved to make chemical sedimentary rock?

Answer 11

calcite CaCo3 in the ocean

Question 12

What are clastic/siliciclastic sediments?

Answer 12

Minerals that contain silica SiO2:
quartz, feldspar, hornblende, etc.

Question 13

What is sediment texture?

Answer 13

How we describe rocks/sediments
includes:
grain size, sorting, shape, and support

Question 14

What is grain size?

Answer 14

Part of sediment texture
*Applies to clastic sediments: a way to categorize individual minerals in a rock
*>2mm- gravel, pebbles, cobbles
*2mm-0.063mm- sand
*0.004mm- silt
*<0.004mm- clay
*Very coarse-> coarse-> medium-> fine-> very fine

Question 15

What is sorting?

Answer 15

Part of sediment texture
- ranges in grain size
- various grain sizes
well sorted -> poorly sorted

Question 16

What is grain shape?

Answer 16

Part of sediment texture
- angular -> rounded

Question 17

What is support?

Answer 17

Part of sediment texture
- matrix vs. grain supported
- sediments can touch each other (grain)
- sediment can also not touch (matrix)
- chemically bound

Question 18

How do we know the maturity of a sediment?

Answer 18

mature: rounded, well sorted
immature: angular, poorly sorted

Question 19

What are the three components of a sedimentary rock?

Answer 19

1. grain (can touch, sand)
2. matrix (smaller stuff in between, silt, finer grain)
3. cement (glued together, iron oxide, silica, calcium carbonate, etc)

Question 20

What are the weathering processes?

Answer 20

1. Chemical
2. Physically, mechanical
3. both

Question 21

What is exfoliation?

Answer 21

mechanical weathering
like peeling an onion
when the granite’s confining stress and pressure gets released as it surfaces, it expands

Question 22

Why does a puzzle rock break apart?

Answer 22

thermal weathering
temperature extremes cause thermal expansion and contraction which cause a rock to fall apart

Question 23

How do dry areas affect rocks?

Answer 23

• If salt gets into the cracks it degrades it
• they are corrosive
• they also expand and contract

Question 24

How does the cold affect rocks?

Answer 24

When water freezes it expands breaking a rock apart if it gets in its cracks

Question 25

What are examples of mechanical weathering?

Answer 25

rainfall and temperature and roots (biological activity) and fires, freeze thaw

Question 26

What are the four major chemical processes?

Answer 26

1. solution
2. redox
3. hydrolysis
4. chelation

Question 27

What is saprolite?

Answer 27

Decomposed rock/ sand

Question 28

What are core stones?

Answer 28

partially decomposed rock

Question 29

What is the weathering front?

Answer 29

the contact between the solid rock and where it is being decomposed

Question 30

What is soil?

Answer 30

where the saprolite is organized into horizons

Question 31

What is granite?

Answer 31

A typical mineralogically homogeneous igneous rock composed of quartz, feldspar, and hornblende

Question 32

What is a corestone?

Answer 32

The unweathered core of a weathering interface created by weathering proceeding rapidly along joint and fractures that easily transmit water.

Question 33

What are chelators?

Answer 33

Organic acids that are able to complex insoluble cations like iron and aluminum

Question 34

What is physical weathering?

Answer 34

the mechanical breakdown of rock into smaller pieces

Question 35

What is chemical weathering?

Answer 35

the chemical transformation of minerals in rock, typically with the loss of mass

Question 36

What are the main master horizons in a soil?

Answer 36

A, B, and C

Question 37

What is sand?

Answer 37

Any detrital material (sediment) that falls between 0.064 and 2 mm in diameter

Question 38

What is the material that creates isovolumetric chemical weathering of rock called?

Answer 38

saprolite

Question 39

Why does the study of sediment and sedimentary rocks care about rock weathering and soils?

Answer 39

weathering and soils generate clastic detritus that will eventually become new sedimentary rocks

Question 40

How is soil developed?

Answer 40

climate, organisms, relief, parent material, and time