GEOL 462: Principles of Sedimentology and Stratigraphy

Lecture 02: Thursday, January 15, 2009

Topics
1. Types of sediments and sedimentary rocks
2. Types of terrigenous sediments and sedimentary rocks
3. Sandstone and petrography
4. Siltstone, mudstone, claystone, and shale
5. Compositional maturity of Clastic sedimentary rocks
6. Textural maturity of Clastic sedimentary rocks
7. Grain size population analysis

Types of Sediments and sedimentary rocks
a. Understand the principle components of sedimentary rocks
b. Understand the basic types of sedimentary rocks and their potential sources of components
c. Refer these to Fig. 2.1 of the textbook

Types of terrigenous sediments and sedimentary rocks
• Sediments to sedimentary rocks: what's the journey?
• What's the grain size of a very fine-grained sandstone? siltstone?
• If the Phi = -2, what grain size (in mm) of the sediment are you referring to?
• What percentage of mud does a muddy sandy conglomerate have?
• What information does a clast-supported conglomerate tell you about the depositional environment?

Sandstone and petrography
• What percentage of quartz does an arkose have?
• What percentage of quartz does a lithic arenite have?
• What percentage of quartz does a lithic wacke have?
• What percentage of matrix does a subakose have?
• What percentage of feldspar does a greywacke have?

Siltstone, mudstone, claystone, and shale
• What is the grain size of clays?
• In what circumstances you call a mudstone a claystone?
• What is the difference between a mudstone and a shale?
• Are the clay minerals detrital grains or precipitates?
• What techniques are needed to identify the clay minerals?

Compositional maturity of clastic sedimentary rocks
• What is meaning of the compositional maturity?
• Between a quartz arenite and an arkose, which one has a better compositional maturity?
• Between a greywacke and an arkose, which one has a better compositional maturity (tricky!)?

Textural maturity of clastic sedimentary rocks
• What information should be included in evaluating the textural maturity of clastic rock?
• Between a wacke and an arkose, which one has a better textural maturity (assume all other parameter are the same) ?
• What does a well-sorted sandstone tell you about the depositional environment?
• What do rounded clasts tell you about the depositional environments?

Grain size (granulometric) analysis
• How to do a granulometric analysis of conglomerates?
• How does a cumulative frequency curve tell you about the sorting of sandstones?
• How to do a granulometric analysis of a consolidated sandstone?