N023 Salt Tectonics Field Seminar: Diapirs and Associated Deformation (Nova Scotia, Canada)

Course Facts

Course Code:
N023
Duration:
4 days
Type:
Field
Physical Demand:
Moderate
CEU:
3.2 Continuing Education Units
PDH:
32 Professional Development Hours
Certificate:
Certificate Issued Upon Completion

Summary

This field and classroom course examines salt diapirs developed in a Carboniferous extensional basin. Diapirs penetrate clastic strata of varying competence (sandstones, siltstones, shales) and extensive coastal sections expose diapir margins that exhibit salt-related deformation features, both syn- and post-depositional in origin. Salt-body influence on sediment pathways is also examined. Classroom sessions review imaging and interpretation issues, salt structural styles, deformation and trap geometries.

Duration and Training Method

A four-day field and classroom course with a 70:30 split between these activities. Training is provided by a combination of field observation and exercises, evening lectures and workshop-style seismic exercises.

Participants will learn to:

  1. Compare the mechanical properties of salt with other sediments and evaluate the physical constraints on salt flow, and how diapirs are triggered and grow.
  2. Predict how salt movements affect adjacent sedimentary sequences and how salt-related deformation differs with depth of burial and gross mechanical properties of the sediments.
  3. Assess the likely effects of near-diapir faulting and folding on reservoir compartmentalisation and seal. Evaluate likely fluid flow barriers and pathways.
  4. Interpret sedimentary and structural features near diapirs and describe how they relate to salt movement.
  5. Characterise the internal structure of diapirs and predict cap-rock development.
  6. Relate the thermal eff ects of salt diapirs to issues of heat fl ow and hydrocarbon maturation in salt basins.
  7. Judge the pitfalls of seismic imaging around salt bodies and be able to interpret seismic data around a variety of salt structures.

This field and classroom course will examine four salt diapirs along coastal sections developed in a Carboniferous extensional basin. These diapirs have been subsequently affected by a late Carboniferous inversion event and they penetrate Carboniferous clastic strata of varying competence (conglomerates, sandstones, siltstones, shales and coals). The diapirs are exposed in continuous cliff sections which extend for over 2km up to 50m in height and exhibit salt-related deformation features, both syn- and post-depositional in orgin. The influence of salt on sediment pathways is also examined.

Classroom sessions will review salt tectonics styles in rift basins, types of deformation seen around salt bodies and discuss trap geometries. Sub-salt imaging difficulties, velocity anomalies and seismic interpretation problems related to salt will also be covered.

The objectives of the field element of the course are to examine the following:

  1. Development of upturned drag and flap folds in different types of overburden buried to different crustal levels.
  2. Fault patterns in overburden rocks, radial and concentric faults. Reservoir compartmentalisation and damage.
  3. Development of unconformities around salt structures.
  4. Contractional rejuvenation of diapirs.
  5. Salt dome topography controls of sedimentation.
  6. Internal deformation of diapirs with layered clastics, anhydrite and dolomite interbeds.
  7. Cap rock development.

Evening discussion will address the following points:

  • Physical principles of salt flow.
  • Deformation patterns of overburden rocks around salt diapirs.
  • Salt structure control on sedimentation using examples from the Red Sea, Gulf Coast of Mexico, North Sea and the South Atlantic margins.
  • Formation of diapiric drag zones.
  • Review of experimental modelling and what this can teach us about salt tectonics.
  • Criteria for recognising compressional rejuvenation of salt diapirs.
  • Participants are encouraged to bring seismic data form their own areas of interest for a  workshop discussion in the evenings.
  • Models for cap rock development.
  • Imaging problems through complex salt structures.

Itinerary (subject to weather and tides)

Day 0:

Arrival into Halifax and transfer to Cape Breton Island. Evening ice-breaker and group dinner.

Day 1:

Morning classroom session -Introduction to salt rocks, tectonics and sediment interaction. Outline objectives of field trip. Safety brief.

15 minute drive to Broad Cove Diapir. Example showing drag zones developed in shale, sand, silt around diapir developed at 1-2 km below surface.

Evening Discussion. Drag Zone and deformation around salt diapirs.

Day 2:

Port Hood Island Diapir. 20 minute drive and 15 minute ferry. Example of diapir growth during sedimentation. Unconformities and sedimentation patterns, fracturing and fluid flow around salt diapirs developed at less than 300m below the sea bed.

Evening Discussion. Interaction between salt-induced bathymetry and sedimentation.

Day 3:

15 minute drive. Finlay Point and Coal Mine Point Diapirs. Deformation of sandstones and shales developed within 1 km of burial. Showing brittle faulting in sandstones and shales, and granulation seam damage in sandstone reservoirs.

Evening Talk. Faulting above salt diapirs and reservoir compartmentalisation.
 
Day 4:
Classroom work - seismic workshop session. Afternoon return to Halifax. EU-based participants may fly out, US-based participants overnight in Halifax.

Lodging will be in a hotel attached to the Glenora Malt Whisky Distillery near Mabou, which has chalets set on the hillside above the main building and rooms in the main hotel. Participants may be required to share chalet-style accommodation depending on availability.

Special Requirements

The tutor also requests that participants bring their own data for discussion. Presentations or poster-type material provide the basis for stimulating discussion within the group and enhance the benefits of the course considerably.

Who should attend

The course will benefit exploration and production geoscientists and engineers working in areas affected by salt tectonics and especially those concerned with the details of the salt-sediment contact zones.

Prerequisites and linking courses

There are no prerequisites for this class but participants are assumed to have a basic understanding of sedimentology and structural geology.  Prior attendance on one of the Nautilus Training Alliance fundamental structural geology (N016, N116) or seismic interpretation classes (N090, N160) would be useful for those who have little experience in either structural geology or salt tectonics.

There are a number of classes in the Nautilus Training Alliance portfolio that deal with salt tectonics and those wishing to broaden their understanding of salt-related deformation would benefit from attendance on one or several of these. N232 (Salt Tectonics: Spanish Outcrops, Global Styles) is a combined field and classroom course that addresses the fundamentals of salt deposition, mechanics and structural style and visits diapirs exposed in the Basque-Cantabrian Pyrenees of northern Spain. N163 (Salt Tectonics and Coeval Sedimentation in the Paradox Basin, Utah) is a dominantly field-based class that looks at similar topics in the Paradox Basin salt province. Classroom courses dealing primarily with salt tectonics are: N071 (Geological Seismic Interpretation Workshop: Salt Tectonics) and N149 (Practical Salt Tectonics).

In addition, other field classes consider aspects of salt tectonics within their curriculum, for example: N016 (Structural Geology for Petroleum Exploration); N041 (Extensional Tectonics and Normal Fault Patterns); and classroom courses N090 (Seismic Structural Styles Workshop) and N160 (Seismic Interpretation of Structural Styles).

The physical demands for this class are MODERATE according to the Nautilus Training Alliance field course grading system. The outcrop sections are on the coast and access will be down coastal paths and along beaches. There are a number of rocky and slippery sections along the beach outcrops which require a moderate degree of agility and care to successfully navigate. Each day will be focussed on a particular coastal section which will involve hikes of 2 to 4 km only.

Note that this field area is located on the north Atlantic coast of Canada and that the weather may be unsettled and cool - participants should bring suitable clothing and footwear. Weather permitting there will also be a boat trip to view coastal localities.


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Ian Davison

Great course. Excellent geology with good exposure in a beautiful locale. Instructor and safety/logistics person were both top notch.