GEOS1211 Lecture Notes - Lecture 6: Sydney Basin, Clay Minerals, Depositional Environment
14 Jun 2018
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Lecture 6 learning outcomes
• Describe and give examples of the importance of sedimentary rocks to society and
environment
Energy resources- sedimentary environments are where are deposits of oil, gas and coal formed and
sedimentary sequences are where they are fund today. These sequences may also be used for
carbon sequestration
Water resources- naturally occurring water reservoirs (aquifers) occur within sedimentary rock
sequences 9e.g. Sydney Basin)
Palaeontology- all fossils (evidence of past life forms and indicators of past environments and
ecosystems) occur exclusively within sedimentary sequences
Pollution containment- as many sediments/sedimentary rocks can be porous and permeable, its
important to understand the location of these within areas of pollution spill to ascertain
contamination within the water table and aquifers
Placer deposits- ay deposits of gold (icludig he worlds largest ecooic cocetratio o the
Witwatersrand of South Africa), diamonds, sapphires and heavy minerals (zircon, ilmenite, monazite,
magnetite) are concentrated within sediments and/or ancient sedimentary sequences
Building materials- many of our widely used building materials are derived from sediments (clay,
gravel, sand, mud) or sedimentary rocks (blocks, facing stones, bricks, concrete and cement)
Sedimentary structures are very important as they provide us with information on the
paleogeography and palaeoclimate. They can also indicate the direction of palaeocurrents of ancient
rivers and seas.
• Describe the formation of sediments and their transportation in different sedimentary
environments
Formation->
- Sediments are broken down fragments of former rocks, minerals or even biological matter
(such as leaves, corals, shells bones etc), e.g. clays and muds, sands, gravels,
- Sediments form from the break-down (both physical and chemical) of pre-existing rocks
(these may be igneous, metamorphic or sedimentary), minerals and biological skeletal
material.
- Factors that control the formation of sediments->
o Climate
o Topography
o vegetation type and amount of cover
o properties of the pre-existing rock
▪ physical ie fractures and grain size
▪ chemical(composition))
o gravity (all sediments flow downhill)
- weathering- the process whereby rocks decay due to the combined effects of air (providing
oxygen) and water (providing reactive solutions). It is a 2 fold process- fragmentation
(known as physical weathering) and decay (known as chemical weathering) always act
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Document Summary
Lecture 6 learning outcomes: describe and give examples of the importance of sedimentary rocks to society and environment. Energy resources- sedimentary environments are where are deposits of oil, gas and coal formed and sedimentary sequences are where they are fund today. These sequences may also be used for carbon sequestration. Water resources- naturally occurring water reservoirs (aquifers) occur within sedimentary rock sequences 9e. g. sydney basin) Palaeontology- all fossils (evidence of past life forms and indicators of past environments and ecosystems) occur exclusively within sedimentary sequences. Pollution containment- as many sediments/sedimentary rocks can be porous and permeable, its important to understand the location of these within areas of pollution spill to ascertain contamination within the water table and aquifers. Placer deposits- (cid:373)a(cid:374)y deposits of gold (i(cid:374)cludi(cid:374)g he world(cid:859)s largest eco(cid:374)o(cid:373)ic co(cid:374)ce(cid:374)tratio(cid:374) o(cid:374) the. Witwatersrand of south africa), diamonds, sapphires and heavy minerals (zircon, ilmenite, monazite, magnetite) are concentrated within sediments and/or ancient sedimentary sequences.
