sandstone Flashcards
What are the four major components of Sandstone?
Framework Grains, Matrix, Cement, Pore Spaces
Framework Grains control mineral stability and maturity; Matrix indicates maturity levels; Cement affects hardness, porosity, and color; Pore Spaces determine reservoir quality.
What percentage of Framework Grains typically constitutes Sandstone?
50-90%
Framework Grains include Quartz, Feldspar, and Lithic fragments.
What is the significance of the Matrix in Sandstone?
Indicates maturity levels
High matrix = wacke (immature); Low matrix = arenite (mature).
What types of cement are found in Sandstone?
Silica, Calcite, Iron oxide
Cement affects hardness, porosity, and color.
What is the role of Pore Spaces in Sandstone?
Determines reservoir quality
Pore Spaces are the empty spaces between grains.
How is Sandstone classified?
Based on the proportions of Quartz (Q), Feldspar (F), and Lithic Fragments (L)
The classification focuses on QFL ratios.
What characterizes Quartz Arenite?
> 90% Quartz, well-sorted
It represents high maturity and stable cratonic environments.
What is the primary source of Feldspathic Arenite (Arkose)?
Granitic source
Arkose contains more than 25% Feldspar and has a pinkish color.
In what type of environment does Lithic Arenite form?
Tectonically active basins
It contains more than 25% Lithic Fragments.
What is the depositional environment of Greywacke?
Deep-marine turbidites
Greywacke is poorly sorted with a high matrix and is found in subduction zones.
What does Glauconitic Sandstone indicate?
Marine transgression
It is rich in Glauconite and useful in sequence stratigraphy.
What are the economic significances of Quartz Arenites?
Petroleum & groundwater reservoirs
They have high porosity, making them excellent reservoirs.
What is one use of Sandstone as a building material?
Monuments (e.g., Red Fort, India)
Sandstone is used in various architectural applications.
What minerals are often found in iron-rich sandstones?
Fe, Mn, and U
These sandstones host significant mineralization.
What do Lithic Arenites indicate in geological studies?
Active orogenic zones
They form in high-energy environments.
True or False: Quartz Arenites are the least stable type of Sandstone.
False
Quartz Arenites are the most stable and serve as excellent reservoirs.
Fill in the blank: Sandstones vary based on composition (____ ratio) and textural maturity.
QFL
The QFL ratio refers to the proportions of Quartz, Feldspar, and Lithic fragments.
What is the significance of classification in Sandstone studies?
Crucial for provenance studies
Classification helps in understanding the source and transport history of sediments.
