3D Sediment Aquifer Mapping

Ontario, Canada

Abigail BurtOntario Geological Survey

Today’s Talk

• Introduction• Why is the OGS doing 3-D mapping?

• Where are we working?

• What are the goals?

• How do we go about 3-D mapping

• What do we produce?

Why is the OGS doing 3-D mapping?

• Contaminated municipal water

• Walkerton Inquiry

• Provincial legislation!!!!!

Legislation

Source Water Protection Plans• Watershed characterization• Water budget• Aquifer recharge• Aquifer vulnerability• Well head protection areas• Threats to drinking water Greenbelt Act

Places to Grow Act

Where are we working?

Build a 3D model of Quaternary deposits

that form regional-scale aquifers and

aquitards

• Reconstruct the regional Quaternary history and develop a conceptual geological framework

• Construct a 3D model of key sediment packages

• Characterize the properties of modelled sediment packages

How do we go about 3-D mapping?

Build a Conceptual Framework

Fieldwork

• Auger and probe holes• Pits and quarries• River and lake bluffs

Glaciolacustrine sediments

Till

Peat

Shallow water glaciolacustrine Glaciolacustrine

Outwash

Peat

Shallow water

Beverly Swamp

Lake Erie DunesDune

Glaciolacustrine

Sediments

DunePeat

Lagoon4135 BP

Southern WetlandsDune

Reactivation

Glaciolacustrine

Sediments

Peat

Till

Dune Reactivation

Glaciolacustrine

Sediments

Peat

4440 BP 8235 BP

Lake Ontario Bluffs

Till

Deformed deep water

glaciolacustrine sediments

Shallow water glaciolacustrine

sediments

Shore

Till

Deformed deep water

glaciolacustrine sediments

Deep water glaciolacustrine

sediments

Shore

Ground-based gravity surveys• Show the least sensitivity

to cultural interference.

• Not affected by stratigraphy (velocity contrasts of stratigraphic units) and depth to water table.

• Simple and cheap

Time-Domain Electromagnetic Survey

Drilling!!!

Detailed Logs

Legacy Data

Reduce and translate

SandSandyQuicksandMedium sandCoarse sand

Sand

New Term Original Term 1

Original Term 2

Original Term 3

Gravel Gravel Packed Water-bearing

Sand Sand Sand Silt

Sand Sand Soft Clean

Clay Clay Sticky Soft

Diamicton Clay Sand Gravel

Diamicton Hardpan NA NA

Building a 3-D Model

Plot borehole

traces

Digitize 3-D points (picks)

Building a 3-D Model

Fill spaces with

blocks

Create 3-D wireframe surfaces

What really goes on….

Tales from the Orangeville Moraine

DEM

Drift Thickness

Surficial Geology

Surficial GeologyWe are a long way from Niagara…

• Lots of till (green)

• Lots of sand and gravel (orange and beige)

• LANDFORMS!!!!

What about those tills?• Tiny windows into older glaciations

• Some tills look different, some don’t

• PSA, Chittick, HM, Pebbles, fabrics

• LANDFORMS

Outwash!

• Paleoflows (sediment source)

• Flow velocity

• Ice margins

Bars (no, not that kind of bar)

Bar Front

Bar coreWaning Flow

The Orangeville Moraine

The Orangeville Moraine

Coarse

And fine

Stratigraphy!

Drilling!

Conceptual Framework

Bedrock Surface

Older Sediments

• Weathered bedrock and contact aquifer

• Older tills (aquitards)• Stratified sediments

overlying the tills (aquifers)

NW

SE

5 cm

5 cm

5 cm

5 cm

The magic of sub-till organics!

5 cm

>52 20054 500 +2 900

• Radiocarbon dating• Pollen / macrofossils

Late Wisconsin Glaciation

• Early lobate flow• Main glaciation

characterized by regional flow

NW SE

5 cm

5 cm

5 cm

Breakup of Catfish Creek Ice• Ice thins and

begins to break up• Glaciolacustrine

sediments and fine-textured diamicton deposited

• Rare coarse-textured glaciofluvial sediments

NW SE

5 cm

5 cm

5 cm

Orangeville Moraine

• Paleoflow directions to the southwest

• Coarse-textured proximal sediments

• Fine-textured distal sediments dominant

NW SE

Ice from all directions

• Port Bruce advance of Ontario, Huron and Simcoe lobe ice

• Advanced over the flanks of the Orangeville moraine

• Drumlins, streamlined landforms, till fabrics

NW SE

5 cm

5 cm

5 cm

Final Advance• Advance of

Ontario lobe ice

• Paris moraine (end moraine)

NW SE

What our clients want to know

• Aquifer or aquitard?

• Location / continuity?

• Thickness / volume?

• Surface elevation?

• Pathways?

• Characteristics?

• Reliability?

The subsurface revealed!

• Stratigraphy

• Pathways?

Interpretation

Thickness

Surface Elevatio

n

Don’t over do it!

Are buried valleys important?

YES!!!

Aquifer or drain?

Monitor!

Products: guiding principles

• Standardized from one project area to the next

• Terminology and geologic conceptualizations need to be standardized to allow for merging of models

• Products need to be useable by a wide range of clients

• Need to release products that eliminate the need for high-end computers or software to use the data.

Products

Groundwater Resource Studies

Datamine exports of volumes and grids for hydrogeologists

and geoscience specialists

Interactive drillhole data

Maps and Cross-Sections

Prepared cross-sections

Aquifer recharge and vulnerability maps

Structural contour and isopach maps

Cross-Section Viewer and Google Earth

Groundwater Applications

• Source water protection

• Search for new water supplies

• Groundwater flow models

• Tier 2 and 3 water budgets

• Monitoring wells (PGMN)

• Sanitary landfill planning

• Remediation of Ontario’s brownfields

• Nutrient management plans

Resource Applications

• Protection of sensitive ecosystems

• Environmental Bill of Rights

• Geotechnical studies

• Bridges and overpasses

• Building foundations

• Resource development

• Search for buried aggregate

Scientific Applications

• Stratigraphic studies

• Improved regional framework

• New radiocarbon dates

• Climate Change

• The past is the key to the future

Measured sections, borehole logs and geophysical profiles are excellent primary data

sources

Summary

• Rural and urban Ontarians rely on overburden aquifers for their water supply.

• The OGS is engaged in the effort to find, assess and protect Ontario’s

groundwater resource through regional scale and targeted 3-D surficial

aquifer mapping projects.

• Each 3-D project addresses

• Quaternary history

• Conceptual framework

• 3-D mapping

• Interpretation

• Groundwater resource reports, digital datasets, maps, cross-sections and

Google Earth applications are key products.

http://www.geologyontario.mndm.gov.on.ca/