Lecture 6 - Evaporaties

Question 1

What are evapourites?

Answer 1

Bedded sedimentary rocks that crystallise from brines

Question 2

What are brines?

Answer 2

Hypersaline solutions

Question 3

What does it tell us about the climate (the presence of evapourites)

Answer 3

Precipitaion, surface heat flow, groundwater in from and a hot and arid clime

Question 4

Non-marine evaporites?

Answer 4

forming in closed lakes with no external output in an arid or semi arid region. Derived from chemail weathering enterting a lake. Evapouration occours and the remaining water is enriched in salts (brine concentration).

Question 5

What causes the evapouitres to form?

Answer 5

Over saturation means the water cannot hold anymore

Question 6

Modern example

Answer 6

Death Valley

Question 7

What is solubility

Answer 7

The solubility of a substance is its ability to dissolve a solution

Question 8

NaCL solubility factors….

Answer 8

…its super soluble which means alot of it can go into water

Question 9

Explains the bullseye pattern

Answer 9

The lest soluble minerals are found on the outside and the most on the inside.

Question 10

Bullseye pattern in death valley concentrations

Answer 10

the most soluble minerals are found in the center and are highly concentrated, the least soluble is concentrated on the outside.

Question 11

Salt lake, Utah an example of a man made salt late

Answer 11

There are concentrated by evapouration, this makes the extraction of salts easier for commerical use

Question 12

Sabkha Evapourites, what are they?

Answer 12

Hypersaline supratidal flats, salt pans and esturies in the persian gulf of the middle east.

Question 13

What occours at these sabkha places?

Answer 13

there is a continual source of minerals, such as upesurging sea water. Seawater floods. Here there is constant evapouration meaning salts acculmate rapdily.

Question 14

What are the sakbha evapourites

Answer 14

Anyhdruites, Gypsum, Dolomite

Question 15

how are these deposits of evapourites different from today

Answer 15

They are much much larger.

Question 16

Explainantion of the deep water basin model

Answer 16

High tidesv bring in water over the top of a sill forming a “sill”, evaporation from brine causes the crystal formation.

Question 17

Modern example of the deep water basin

Answer 17

The dead sea

Question 18

Shallow water basin model explanation

Answer 18

Sediments deposited in the region of the North Sea, in a basin separated from other oceans by a structal barrier (such as a shallow sill) This leads to evapouration and accumlution of evapourites

Question 19

Shallow water in a deep water basin explanation

Answer 19

Water spills or seeps through a sill, which leads to shallow water acculuation. THeir is a perodic over flow and when this occours the water is depositited. This then goes on to evaporate.