Closely examine the individual grains in Sample S2. Which of...

Name: Problem 7, Chapter 10: Laboratory Manual for Introductory Geology
Uploaded: 2021-07-29T17:37:36-08:00
Duration: 1 min 19 s
Channel: Christina Sorrentino
Description: Closely examine the individual grains in Sample S2. Which of the following is true about its maturity? a. It is mature because it contains a variety of different minerals. b. It is immature because it is poorly sorted. c. It is mature because it contains mostly rounded quartz grains. d. It is immature because the grains are jagged.

Closely examine the individual grains in Sample S2. Which of the following is true about its maturity? a. It is mature because it contains a variety of different minerals. b. It is immature because it is poorly sorted. c. It is mature because it contains mostly rounded quartz grains. d. It is immature because the grains are jagged.

Closely examine the individual grains in Sample S2. Which of the following is true about its maturity?
a. It is mature because it contains a variety of different minerals.
b. It is immature because it is poorly sorted.
c. It is mature because it contains mostly rounded quartz grains.
d. It is immature because the grains are jagged.

Key Concepts

Grain Roundness

Grain roundness describes the degree of smoothing of the edges and corners of sediment particles, which occurs through abrasion during transport. Highly rounded grains typically indicate a long history of transport and mechanical weathering, a trait of mature sediment, whereas jagged or angular grains often suggest limited transport and minimal abrasion, implying an immature state.

Sedimentary Maturity

Sedimentary maturity refers to the stage of weathering and transport a sediment has undergone, reflected in its physical characteristics such as sorting, roundness, and mineral composition. Mature sediments typically show evidence of extensive transport, which leads to well-rounded grains and a predominance of resilient minerals, while immature sediments have not been subjected to prolonged weathering and transport, resulting in angular grains and a more varied mineralogy.

Sorting

Sorting is the degree to which sediment grains are uniform in size. Well-sorted sediments indicate that the grains have been transported over long distances by consistent energy conditions, allowing finer particles to be winnowed away and leaving behind similarly sized grains. Poor sorting suggests a shorter or more variable transport history, where a mix of grain sizes is deposited together, often characteristic of immature sedimentary deposits.

Mineralogical Composition

Mineralogical composition refers to the range of minerals present within a sediment. In sedimentology, a limited mineral composition dominated by durable minerals such as quartz is usually a sign of maturity, as less resistant minerals are weathered away during transport. Conversely, a varied mineral composition may be indicative of an immature sediment where the original rock types have not been extensively reworked.

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