Virtual course in Fluvial Landscape Reconstruction from the Sedimentary Record

What: Virtual lessons and discussion opportunities about observing and interpreting ancient river deposits

This course has been developed as part of NSF Award 1455240 and in collaboration with SEPM, the Society for Sedimentary Geology.

Instructors: Dr. Liz Hajek, Dr. Sinead Lyster, and the PSUPER SED Research Group: Dr. Mohit Tunwal, Xiaoni Hu, Safiya Alpheus, Jasmine Walker and more

Goals:

• expose participants to methods for measuring and interpreting paleomorphodynamic information from sedimentary outcrops,
• improve participants’ ability to identify, measure, analyze, and interpret paleomorphdynamic features, and 
• promote networking and idea transfer through collaborative, participant-led activities

 

Course Overview:

• Introduction and review of key concepts, perspectives, and approaches for paleo-landscape reconstruction from fluvial deposits
• Target audience: graduate students, postdoctoral scholars, and early-career researchers with some experience in geology, sedimentary geology, sedimentology, sediment transport, or geomorphology and an interest in fluvial deposits
• Part 1: series of ~6 lectures and activities to establish background and working framework (mid Feb-April)
• Part 2: participant-led sharing, discussions, and reviews of datasets and of field-campaign plans (April-early May)
• Course delivery will be via Zoom and a course Slack channel to facilitate both synchronous and asynchronous participation. Live Zoom times will be staggered to support global participation. Slack channel will enable continued discussion, Q&A, and participant sharing and interaction.  

 

Part 1 – Lessons Outline

In each unit we will:

• Provide background and description of approaches/methods related to the topic
• Discuss and explore examples of how the method can be applied (outcrop and subsurface data)
• Discuss uncertainties and develop guidelines for best practices for data collection and interpretation

1: Introduction to river networks and the stratigraphic record 

• Boundary conditions (subsidence, sediment supply, base level) and boundary-condition limits on Earth in different tectonic settings
• Fluvial fundamentals (slope, shear stress, shield’s stress, cohesion, hydraulic geometry)
• BQART & sediment-transport thresholds
• Fluvial morphodynamics: a hierarchical approach (channel network/avulsion; channel belt/migration/planform; channel/bar dynamics; bedform/bed roughness dynamics)
• Stochastic vs. deterministic sedimentation in fluvial networks
• Fluvial response timescales (channel vs. landscape) 
• Motivations for understanding fluvial deposits (providing paleo-environmental context; constraining long-timescale and low-recurrence fluvial processes; understanding controls on subsurface reservoir/aquifer/mineral distributions and fluid flow) 

2: Scaling ancient fluvial networks 

• Leveraging hierarchy to assess scale (top down vs. bottom up)
• Paleoflow depth & width estimation
• Paleoslope & paleo-discharge reconstructions
• Handling uncertainty; paleohydraulic uncertainty; reconciling bed vs. bar vs. belt measurements; sampling scale vs. paleo-system scale: evaluating coverage and matching research question to anticipated resolution

3: Preservation across the fluvial hierarchy 

• Controls on preservation at channel belt, channel thread/bar, and bedform scale
• Belt – “amalgamation”, avulsion-generated units, channel/floodplain relationships
• Bar/thread – Intrachannel-belt facies (bars, thalweg, low-flow zones, channel abandonment), geometry & scale (thickness, width, persistence, preservation)
• Bed – bedform migration and preservation

4: Floodplain deposits and channel:floodplain coupling

• Avulsion mechanisms and styles
• Styles of overbank deposition
• Controls on crevasse-splay deposition
• Floodplain drainage
• Paleosediment supply and controls on channel-floodplain coupling
• Floodplain & landscape relief and accommodation creation and filling (alluvial ridge to floodplain lows; fans, valleys and other channel-network morphologies; “smooth” vs. “rough” floodplains)
• Identifying paleo avulsion deposits 
• Compensation, clustering, and paleo-landscape topography

5: Fluvial records of paleoenvironmental conditions

• How climate, tectonic, and landcover signals might influence rivers and might be propagated to the stratigraphic record
• Floodplain approaches (paleobio; geochem; paleosols)
• Facies approaches (planform; “flashy” vs. regular flow)
• Bedform preservation approaches
• Uncertainty, cautions, and caveats

6: Integrating observations across scales

• How different scales provide different types of insight
• Hypothesis testing using comparisons across scales 
• Limits of interpretations and comparisons (depending on data availability and system scale)
• Comparisons to numerical and experimental models
• Leveraging data from modern systems

• Defining a question: paleoenvironmental constraint? Understanding of fluvial dynamics? Response to external forcing?
• Identifying key scales and data coverage (how much data can you get and what degree of spatial/temporal sampling can you achieve?) 
• Data collection approaches (wells, seismic data, outcrop (approachable), outcrop (virtual/remote)
• Data archiving, sharing, and storing (Strabo Spot; digital outcrop models; subsurface data)

 

Part 2 – Participant-led activities

Depending on participant needs and interests we will facilitate participants:

• Leading discussions on specific topics and papers
• Sharing their research results
• Exploring datasets
• Reviewing and discussing plans for data collection
• Coordinating group projects (data compilation, comparisons, modeling exercises, etc.)