Porosity Flashcards
Types of porosity in consolidated seds and rocks
- primary
- Secondary
- vesicular
Explain primary porosity
Porosity that forms on the surface of the earth at the time the seds were deposited
Explain secondary porosity
What are the two types
Porosity that forms in a rock after lithification (sedimentary) or crystallization (meta/ign)
- solution
- fracturing
Explain solution as a type of porosity
Porosity firmed by dissolution of a portion of a rock
-usually a carbonate (line/dol) by acidic solutions percolating through rocks
Explain fractures as a type of porosity
Porosity firmed by breaking of the rock (extrusive ign(basalt, rhyolite, andesite)) under stress (I.e. folding or faulting) or by differential cooling (columnar jointing) or volcanic rock
Explain vesicular as a type of porosity
Forms in basalts as gas escapes from the lava on earths surface
Porosity In Unconsolidated Seds Is Caused by:
- particle size
- Grain shape
- grain size distribution
- Particle arrangement
Do large or small particles have greater porosity
They have the same
What has more porosity: spheres or platlets?
Platlets
What has greater porosity: well or poorly sorted grain size distributions?
We’ll sorted
What has greater porosity: cubic or face centred packing
Cubic
Cubic doesn’t exist in the real world
What has more porosity: consolidated or I consolidated sediments?
Unconsolidated
Because they are less compact and not cemented together
What has a higher porosity : silt or gravel?
They have the same because they are both spheres
What has the highest porosity for seds and rocks
Clay because it’s shaped as platlets
What is the symbol for permeability
Units?
k (lower case
M^2
