Lecture 14 resources 5 sediment hosted

Question 1

Where do sediment hosted deposits form

Answer 1

sedimentary rocks

Question 2

examples of large deposits

Answer 2

Periman basin - europe (UK to germany)
Katangan basin - Zambia
80% of the deposits are in these two basins
Process of Cu redistribution is common, rare for this to cause substantial ore.
Special variations of common basin processes
must have acted to have formed the supergiants.

Question 3

how much do sediment hosted contribute economically

Answer 3

a quarter (25%) of the worlds copper production.
second most important after porphyry.
- many of the giant and super giant = very high grade (higher than porphyry) = good for production.

Question 4

explain the red bed concept

Answer 4

Red beds, interact with salty brines
there are different rocks above - basement rocks are the metal source (igneous volcanic rocks) where the copper originates from.
red beds - weathering of the basement rock - interacted with residual brines.
initially oxidising ->reducing conditions which is where mineralisation occurs and copper is precipitated.

Question 5

What is malachite?

Answer 5

hydrated copper carbonate

Question 6

What’s a EHPH diagram

Answer 6

Diagram presents how copper as hydrated copper chloride compounds are mobilised in this brines and deposited as different copper Minerals at different conditions.
oxidising conditions
EHPH is an indicator
above 0 = oxidising conditions and mobile
below 0 = reducing conditions and precipitated

Question 7

What’s the Permian Basin

Answer 7

North sea to UK and Germany

Question 8

Explain the geology of the Zambian mine

Answer 8

Geology: Granite bedrock, then sandstone and conglomerates, then reducing layer (shale, siltstone)
most mines are located along this reducing layer of shale and siltstone.
Granite is the source of copper - mobilised through leaching by brines and deposited in the overlaying rocks.
tectonics play a role - there is rock deformation in the rocks - there are sulphides

Question 9

what is the difference between porphyry copper and sediment hosted copper deposits.

Answer 9

porphyry deposits = magmatic and igneous
sediment hosted = leaching from base rock