Rocks To Sediments

Question 0

“What are the deposits called that are derived from the weathering of silicate rocks?”

Answer 0

Siliciclastic sediments

Question 1

Chemical weathering

Answer 1

Occurs when minerals react with water containing dissolved substances, particularly carbon dioxide.
CO2 (g) + H20 (l) = H+ (aq) + HCO3 (aq)

Question 2

Agents of weathering

Answer 2

Physical process such as rain , thermal
Biological such as root Penetration
Chemical processes such as dissolution acid rain

Question 3

Physical weathering frost shattering

Answer 3

Water undergoes a volume increase of 9% on freezing which exerts a pressure increase of 14 Mpa in the cracks of rocks

Question 4

Thermal expansion

Answer 4

daily temperature differences of up to 60°C lead to exfoliation. This is where thin layers of the rock peel off, much like the outer layers of an onion; hence this process is sometimes also termed onion-skin weathering

Question 5

Biological weathering

Answer 5

Roots enlarge crevices and cracks

This leads to rock surfaces being degrade by lichens

Question 6

Minerals that are particularly susceptible to chemical weathering?

Answer 6

Olivines pyroxenes and amphiboles contain crystal structures that contain metal atoms weakly bonded to their isolated (olivine) or chained (pyroxene and amphibole) silica tetrahedra.

Question 7

silicate structure of rock forming minerals

“olivines, pyroxenes, amphiboles, micas, feldspars and quartz”

Answer 7

Olivine's = composed of isolated groups
Pyroxenes = single 1d chain structures
Amphiboles = double 1d chain structures
Micas = 2 d sheet structures
Feldspars and quartz =  are 3d framework structures

Question 8

Least resistant to chemical weathering.

Answer 8

Olivine

Question 9

Most resistant to chemical weathering ?

Answer 9

Quartz si02

Question 10

Compositional maturity in a sedimentary rock

Answer 10

A rock that consists of almost exclusive Quartz

Question 11

Compositional immature rock would be.

Answer 11

A rock consisting of a high percentage of feldspar

Question 12

Chemical weathering of carbonate rocks

Answer 12

Limestone is susceptible to chemical weathering

CaCO3 + H2CO3 >Ca2 + 2HCO3−

Question 13

why is chemical weathering enhanced by warm, wet, tropical conditions?

Answer 13

Higher temperatures and abundant water accelerate chemical reactions, and abundant vegetation increases the availability of organic acids to initiate these reactions.

Question 14

What is the origin of mud on beaches or in estuaries?

Answer 14

Mud consists of clay minerals these are the end products of chemical weathering of various silicate minerals such as:
Feldspars, micas, amphiboles, pyroxenes and olivines.