GEL 1 Lecture Notes - Lecture 20: Algal Bloom, Lithification, Clastic Rock
clastic
● bits and pieces of stuff
chemical
● dissolved in water, precipitated out
biochemical
● remains of organisms such as algae and protists
● can accumulate large volumes of these
Mineralogy
● relatively simple, easy to discern, not very diverse
Texture
● grain size
● snapshot of earth's conditions
○ we can understand how things were moving around when it came to be
○ process that created the rock
Lithification process
● sediment → rocks
● compaction
● cementation
Sedimentation & Sedimentary rocks
● stacked series of rocks
● layering/bedding represents accumulation of material over time
● record of environmental settings at the time it came into being
● gaps in the layers represent time too
Formation
● need a source of sediment
○ dirt or precipitated out of water
1. Weathering
● dissolve in water
● algal bloom remains create precipitate
● physical breakdown
2. Transport
● carrying to some place
● erosion: weathering + transport
3. Deposition
● in a basin (hole in the ground
● usually ocean, lake
● sediment does not make its own basin! needs to already be there
4. Cementation
Document Summary
Remains of organisms such as algae and protists. Relatively simple, easy to discern, not very diverse. We can understand how things were moving around when it came to be. Layering/bedding represents accumulation of material over time. Record of environmental settings at the time it came into being. Gaps in the layers represent time too. Dirt or precipitated out of water: weathering. In a basin (hole in the ground. Sediment does not make its own basin! needs to already be there: cementation. Leads to stable low temp minerals that can be transported. Exposed to water change chemical composition. 1 mol silicate weathered = 1 mol co2 removed from the atmosphere. Dense materials can be transported (large grain sizes) More limited, can only transport fine-grain (smallest clastic size) Consistent grain size so easy to tell. 2 types of transport: wind and ice. Large as even boulders to small stuff. Cant transport as far, but can get into the ocean.
