Sedimentry Rocks Flashcards
(42 cards)
Complete this series:
weathering –> _______________ –> deposition –> _____________
transportation, lithofication
What are the two types of weathering?
mechanical & chemical
Where does mechanical weathering typically happen?
at the surface
What are some common transporting agents?
air, water, ice/glaciers, gravity (ie landslides)
Deposition is due to change in __________.
velocity
What are the two types of lithification?
compaction & sedimentation
How might compaction happen?
Sediments get buried and gravity and pressure compacts them
What are some common types of cement?
hematite, calcite, silica
What might a large grain in a sedimentary rock say about energy and where it’s from?
You can assume fast water or some other high energy depositing agent. Also, it’s generally close to where it came from.
What would the grain size be for a low energy deposition agent? And would that grain be from close by or far away?
Fine.
It came from far away.
A sedimentary rock has layers of fine grain, followed by layers of course. What does this mean?
Change in energy for the deposition environment.
What does grain angularity/roundness say about distance traveled?
The rounder it is, the farther it traveled generally.
** Grain size is overriding factor tho!
What does it mean to say well sorted in terms of sedimentary rocks?
If all the grains are the same size. Also tells about how long the deposition event was. If it’s well sorted them it took place over a period of time, like a beach.
What are some different types of bedding features?
parallel bedding, cross bedding, herring bone cross bedding
When trying to determine direction of current on a ripple mark thats asymmetrical?
It would come from the more gentle slope side in the direction of the steep side.
What would create a bi-directional ripple mark? Uni-directional?
A tidal situation would create bi-directional. Rivers (which generally go in one direction) would create uni.
What would create an egg carton shaped ripple mark?
Something in waist height water would create an interference ripple in a tidal dominated environment
There are environments with giant ripple-like structures. What does this say?
these would be dunes
Completely explain the difference between detrital and chemical (biochemical and inorganic chemical) sedimentary rocks including an example of each.
Detrital sed rx are created via accumulation of material that originates and is transported as solid particles derived from both mechanical and chemical weathering. Chemical sed rx are from soluable material produced largely by chemical weathering — dissolved substances are precipitated by either inorganic or organic processes. An example of det rx are shale, sandstone, conglomerates and breccia. Chemical are limestone, chalk and coral reefs.
Completely explain the process of lithification.
Lithification refers to the process by which unconsolidated sediments are transformed into solid sedimentary rocks. Compaction is the accumulation of material over a period of time that is buried. The weight of the layers burying the material presses the grains closer and closer together and reduces the pore space.
Sedimentation is when liquids carry materials through open spaces of rocks, and act as a cement. Calcite silica and iron oxide are the most common of these cements eventually creating a whole rock body.
What is chemical weathering
Breaking down ionic bonds and rebonding to precipitate out minerals
What is a course, rounded grained sedimentary rock called?
Conglomerate
What is a course, angular grained sedimentary rock called?
Breccia
What is a sediment generally classified as with grain size bigger than 256mm?
Boulder
