Sed-Strat Exam II Study Guide

What minerals are carbonate rocks made of?

Carbonate rocks are made out of calcite, dolomite, and aragonite, all calcium carbonates.

What are the 3 dissolved species in the carbonate system and which predominates in the ocean?

Bicarbonate (most abundant), carbonate, and dissolved carbonic acid.

Where are carbonate rocks made in the ocean?

Carbonate rocks can be found in reefs and platforms where organisms contribute calcium carbonate.

What is the carbonate compensation depth and why does it matter?

The depth in the ocean where calcium carbonate is completely dissolved; important for understanding ocean acidity and sediment records.

What is the difference between eustatic (global) and local sea level?

Eustatic refers to average sea level across the entire ocean; local sea level refers to levels in smaller areas like coastlines.

What are different ways that scientists reconstruct past sea level?

By examining sediment cores, analyzing deposits, and identifying fossils like foraminiferans that indicate past ocean conditions.

What are the differences between a transgression vs. a regression?

Transgression is a rise in sea level, while regression is a fall in sea level.

What are the three main factors that control sediment transport in coastal environments?

River discharge, wave power, and tidal processes.

What are the different types of marine organisms that produce biogenic sediment in the ocean?

Organisms that secrete silica or calcium carbonate, including microscopic phytoplankton and zooplankton.

What factors control the distribution of different types of sediments in the deep ocean?

Source of sediment, current activity, and ocean acidity (CCD).

Where are carbonate sediments primarily produced and preserved in the ocean?

In warm, shallow waters with reefs and calcium carbonate producing organisms; controlled by temperature, light, nutrients, and acidity.

What are common evaporite minerals and in what environments do they form?

Halite, gypsum, anhydrite, and calcite; they form from water evaporation in warm and arid environments.

What are the different types of contacts and unconformities between beds?

Conformable contacts, intrusive, fault, angular, disconformity, nonconformity, and paraconformity.

What are the principles that underlie the discipline of stratigraphy?

Principle of original horizontality, lateral continuity, superposition, inclusions, and facies.

What are the different units of lithostratigraphy?

Supergroup, Group, Formation (primary unit), Member, and Bed or Flow.

Are all lithostratigraphically correlated deposits deposited at the same time?

No, formations can cover multiple time periods; time is not necessarily a separating factor.

Be able to describe Walther’s law in your own words.

Sedimentary environments that appear in a vertical sequence must have been deposited adjacent to one another laterally.

What are the 3 primary factors that control transgressions and regressions?

Average sea level change, tectonics (subsidence/uplift), and sediment supply.

What is the difference between progradation, aggradation, and retrogradation?

Progradation is seaward growth of sediments, aggradation is vertical buildup, and retrogradation is landward retreat of sediments.

What are the different scales of cycles observed in the geologic record?

Eccentricity (orbit shape), obliquity (tilt angle), and precession (wobble of earth's axis).

What are the differences between the three main orbital (Milankovitch) cycles?

Eccentricity influences season duration; obliquity affects seasonal variations; precession changes solstice and equinox positions.

How is seismic stratigraphic data generated?

Vibrations sent through the earth are picked up by equipment when waves bounce off layer boundaries.

How does the locus of sedimentation change along a depositional profile in response to changes in local sea level?

Moves landward during relative sea-level rise (transgression) and basinward during falls (regression).