Geology 1023 Environments & Facies

Sediments are being deposited in various locations simultaneously Conditions vary from place to place –Medium –Speed –Depth –Load –etc.

Environments & Facies Therefore sediments being deposited vary from place to place These changes in lithology are called “facies variations” When comparing rocks deposited at a certain time but under different conditions you may be forced to correlate rocks of different lithology.

Facies variations (p. 166; 5 ed. p. 156)

Facies (p. 166; 5 ed. p. 156)

Facies Previous slide shows the vertical variation in one locality but note that there is also lateral variation at any given time. Walther’s Rule = vertical variation in one locality mirrors lateral variation at one time.

Shelf environments Q1. Fill in the boxes with the terms –(deep sea) canyon –(continental) shelf –(continental) slope –(continental) rise –(abyssal) plain Q2. What do you think will happen? Q3-5. Shake up the jars. What process are you imitating? (see p. 2)

Environments Table on p. 4 gives various lithologies and their associated environments Q6. Fill in boxes with the label of the rock at the back of the lab which you would expect to find there. Note that the rocks are laid out in the correct order. Do not move the rocks. Try to see the pattern of change visible. Check with instructor that you are correct.

Terminology Proximal = closer to source of sediment Distal = further away from source of sediment

Facies map Q7. Rectangle shows distribution of rock types (using same letters as on Q6). Draw boundaries between rock types (facies). These are boundaries between environments Label (using table on p. 4) the environments responsible for each lithology. Draw arrow showing direction of sediment transport.

Isopach lines Isopach lines are lines joining points of equal thickness of sediment package. Q8. Map of various lithofacies in BC, AB and SK. –Draw the boundaries between each facies and complete the pattern (colour) –Construct isopach lines (use coloured pencil) –Answer various questions about relationship between thickness (isopach lines) and facies (pattern/colour)

Transgression & regression Q9. Series of maps of an area which display the change in facies over time (T1 to T2 to T3). Draw boundaries between facies and colour/shade units On the cross section place the boundaries between facies at the appropriate point on the horizontal line and complete the section. Answer the questions.

T3 T2 T1

Questions?