Sedimentary Rocks and Weathering

These flashcards cover key concepts related to weathering and sedimentary rocks as discussed in the lecture notes.

What are the main factors that control the rates of weathering?

Composition, climate, and particle size or fractures.

What does lithification refer to in sedimentary rock formation?

The process by which sediment becomes sedimentary rock, involving compaction and cementation.

What is the primary difference between detrital and chemical sedimentary rocks?

Detrital rocks are formed from solid fragments, while chemical rocks precipitate from solutions.

Which mineral weathers very slowly?

Quartz.

What happens during chemical weathering of silicates?

Quartz remains stable, feldspars form clay minerals, and mafic minerals decompose to oxides.

How does climate affect the rates of weathering?

Wetter and hotter climates increase chemical weathering while colder and dryer climates increase mechanical weathering.

What is spheroidal weathering?

Weathering that occurs in jointed rock due to pre-existing fractures enhancing weathering.

What is the composition of regolith?

Rock and mineral fragments produced by weathering.

What are the types of sedimentary rocks based on their material source?

Detrital, chemical, and biochemical/organic.

How is texture defined in sedimentary rocks?

Based on grain size, grain shape, and grain sorting.

What is the role of surface area in the rates of weathering?

Increased surface area enhances rates of chemical weathering.

What does the Bowen's Reaction Series illustrate?

The crystallization of minerals from magma at different temperatures.

How do we classify sedimentary rocks?

Based on texture and composition.

What are the three types of cement in lithification?

Silica, carbonate, and iron oxide.

Why are sedimentary rocks important for economic reasons?

They may contain coal, petroleum, natural gas, water, and sources of metals.

What is the significance of differential weathering?

It leads to unique rock formations and varying weathering rates across rock surfaces.

How does the structure of minerals relate to their susceptibility to weathering?

Minerals that form at higher temperatures are chemically less stable and therefore more easily weathered.

What does 'parent material' refer to in weathering?

The original rock type that breaks down to form soil and sediment.

What is the significance of mechanical weathering in relation to chemical weathering?

Mechanical weathering increases surface area, which enhances rates of chemical weathering.

What characterizes conglomerate and breccia rocks?

Conglomerate has large rounded grains in a fine-grain matrix, while breccia has angular grains in a fine-grain matrix.