Natural processes: Formation and classification of geomaterials I Flashcards
What is Bowen’s reaction series?
- Shows melting points of different minerals
- Goes from 700 to 1200 degrees
- Olivine melting point 1200 degrees
What does Goldichs dissolution series show?
Most stable to least stable rock
What type of rock is Obsidian?
- Cools down quickly so cannot see individual grains
- So extrusive
How are sedimentary rocks formed?
By surface processes of the rock cycle
What are the two principle groups of sedimentary rocks?
- Clastic
- Non-clastic
What is a feature of clastic sedimentary rocks?
Clastic rocks have been deposited one point in history therefore are either bedded or stratified
What is important for sedimentary rocks to form?
- Depositional environment and sediment availability
What is a matrix?
The material in which something is embedded, either the natural rock that holds crystals, fossils, pebbles, mineral veins, and the like, or the fine-grained materials that surround larger grains in a rock
What can grains look like in sedimentary rocks?
Angular, sub-rounded, well-rounded
How can sedimentary rocks be sorted?
- Poorly sorted = well graded → can compact better (more)
- Well sorted = poorly graded → less able to compact
Type of sedimentary rocks?
- Conglomerate
- Sandstone
- Shale
Types of sandstone found in different areas of the coastal zone?
- Lithic sandstone - deltas
- Arkose sandstone - alluvial fan
- Quarts sandstone - beach
- Graywacke - grains float inside matrix - submarine
What is the Dott classification?
A widely used classification of sandstone types which divides sandstones into Arenites (less than 15% of rock is mud matrix) and Wackes (more than 15% but less than 75% of the rock is mud matrix).
What are features of Shale?
- Formed from compact mud
- Laminated structure and tendency to break along parallel side fragments
- Anisotropy
What does anisotropy mean?
The quality of exhibiting properties with different values when measured along axes in different directions
