Interconnections Hydrosphere meets Lithosphere What is the lithosphere

Interconnections: Hydrosphere meets Lithosphere

What is the lithosphere?

What is the lithosphere? • Includes the crust and the uppermost mantle, which constitutes the hard and rigid outer layer of the planet. • Directly under the lithosphere is the asthenosphere, the weaker, hotter, and deeper part of the upper mantle. • The boundary between the lithosphere and the underlying asthenosphere is defined by a difference in response to stress: the lithosphere remains rigid for long periods of geologic time, where as the asthenosphere is plastic. • The lithosphere is fragmented into plate tectonics, which move independently relative to one another.

Chemical Physical

Review 1) When we say that tectonic plates move, are we talking about the crust flowing or the lithosphere flowing? 2) Where do you think the majority of resources we have on Earth are (i. e. which layer)? 3) How do you think we know the thicknesses and compositions of these layers?

Resources and reserves What is the difference between a resource and a reserve?

Definitions Resource: all materials that can be exploited, whether they would be economic or not. This includes material that we can not yet extract with existing technology. Reserve: the proportion of a resource that can be economically exploited with existing technology. The size of a resource is fixed, but size of reserves can change due to prices and technology. Reservoir: the general name for a storage location for any material, e. g. nitrogen, crude oil, water, iron etc. It is also used for the stored water retained by a dam.

Things to remember: • If there is a profit to be made in extracting an ore, it will probably be done. • The people who make profits from mining are not usually concerned with the problems associated with extraction. • Sometimes it is not economics that prohibits extraction, rather environmental barriers.

Factors affecting mine viability 1. Land conflicts: • If competing land uses are considered to be more important or valuable than mining then the deposit may not be exploited i. e. if more money can be made by another land use, then extraction won’t go ahead. • The issue is that we can’t choose where to locate a mine, the reserve has a fixed location. • Deposits below urban areas are not extracted as the costs of moving the population would be too high.

2. Extraction costs: Overburden - The rock above the mineral that must be removed.

2. Extraction costs: Depth – the deeper the reserve, the more costly the extraction. A choice needs to be made whether to quarry or mine. If you need to quarry, the sides must be angled to prevent collapse – this extremely expensive. If you need to mine, the costs going into tunneling and technology are very high.

2. Extraction costs: Distribution of the mineral deposit – if the reserve is concentrated, then the cost of extraction would be less. If the deposit is dispersed in thin lines or irregular shapes then the cost of extraction greatly increases.

2. Extraction costs: Hydrology – as depth increases, the amount of water that flows into the mine increases. The cost of pumping it out at depth is very high and energy intensive.

3. Processing costs: • reserves can come in many forms; some reserves have mixed components and must be seperated to be useable (e. g. oil sands contain bitumen—form of oil—that must be extracted from the sand).

4. Transport costs: • The distance to market, the ease of bulk transport and the presence of a suitable existing transport infrastructure all affect transport costs. • Transporting minerals longer distances increases costs, but the unit costs go down if bulk transport by rail or large ship is possible.

5. Market economics: • • • The market demand sale value of the minerals control the economic viability of exploiting a particular mineral deposit. The market price is controlled by the demand for the mineral and how much is produced by mines. Exploiting deposits in regions that already have mines is easier because there will be easy access to the existing infrastructure for transport, energy, equipment supplies and a trained workforce.