JOIDOS Resolution Lecture Notes

Location and Expedition Overview

• Currently located offshore from the Great Barrier Reef in Australia, in the Coral Sea.
• ODP Leg 194 aims to reconstruct the magnitude of Mycene sea level.
• Part of various ODP-IoDP expeditions using sequence stratigraphy to study Earth's past conditions.

Introduction to Sequence Stratigraphy

• Definition: Sequence stratigraphy examines genetically related sedimentary units bounded by unconformities and their correlative conformities.
• Importance: Provides a modern perspective on sediments considering spatial and temporal relationships.

Historical Context

• Review of previous lectures: unconformity, chronostratigraphy, lithostratigraphy vs. chronostratigraphic units.
• Sequence stratigraphy emerged in the late 1970s.
• Key Pioneer: Walter, a German stratigrapher, known for Walters' Law.

Walters' Law

• Concept: Stratigraphic record is divided by conformable and unconformable surfaces.
• Stipulation: For a succession to be conformable, vertical and lateral facies distributions must be similar.
• Example:
  • Vertical log example includes:
    • Upper shore face
    • Middle shore face
    • Lower shore face
  • Conformable succession must show corresponding facies vertically and laterally.

Environmental Deposition

• Example of facies succession:
  • Beach facies (sand)
  • Silt (finer facies)
  • Clay (deeper environment)
  • Carbonate mud (deep basin)
• A conformable succession would have a timeline following the dashed red line indicating the order of deposition.
• Conclusion: Lithostratigraphy units are not chronostratigraphic units; lithofacies are time transgressive.

Transgression and Regression

• Important concepts in sequence stratigraphy.
• Transgression: Occurs when base level (equivalent to sea level) rises, causing facies to migrate landward.
• Regression: Reverse process when base level falls.

Erosional Surfaces as Time Surfaces

• Significant concept in sequence stratigraphy: Erosional surfaces can serve as time markers.
• Early Researcher: Elliot Blackwelder (1909) introduced the concept of using unconformities as timelines.
• Unconformity serves as a timeline representing erosion of underlying folded sediments.