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| Title | 3D hydrostatigraphic model of the Quebec City area | ||||||||||||||||
| Date | 2011-01-01 ( publication)
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| Date | 2011-01-01 ( creation)
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| Presentation form | modelDigital |
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| Type | place |
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| Term | Quebec City area | ||||||||||||||||||||||
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| Type | theme |
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| Term | Quaternary | ||||||||||||||||||||||
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| Type | product |
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| Term | 3D Model | ||||||||||||||||||||||
| Spatial representation | vector |
| Language | fra; CAN |
| Character encoding | utf8 |
| Thematic category | geoscientificInformation |
| Extent | -71.800000000,46.667000000;-70.950000000,47.010000000 |
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| Format | |
| Name | GOCAD Model |
| Version | not applicable |
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dataset
Date lineage
Lineage is the description of the sources and steps used to create the current dataset.
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| The type, format and reliability of the data variable and require preliminary processing before the data are integrated into the modeling software. The multitude of data sources requires an assessment of the reliability of the data and standardization of these data (Ross et al., 2005). The well data position and the depth of the various units are integrated into the 3D geological model using a 2D cross-section approach. The geological units were interpreted and drawn on each of the cross-sections and are later integrated in Gocad®. The geophysical data interpretations are validated or modified using wells located near the surveys. Integration of data in the 3D model is done by the application of constraints on the geological unit surfaces. There are 2 types of constraints frequently used, either soft or strict constraint. Strict constraints are used when data are positioned with acceptable accuracy in the 3 axes (XYZ), for example, well markers with maximum reliability. Soft constraints are used when there is uncertainty about the position of the data, but the information related to this data provides additional information on the subsurface geometry of a unit. Similarly, if the interpretation of a thin unit on the geological map indicates that the second unit is located at shallow depth, a soft thickness constraint can be applied to the underlying unit. The interpolation method used is Gocad® Discrete Smooth Interpolation (DSI), which minimizes the surface slope tangent (Mallet, 2002). The constructed surfaces represent the upper contact of the various geological units. A 3D mesh (voxet) of 250m x 250m x 2m was built over the entire study area. The distribution of the cells associated with the units in the different regions of the 3D model is realized as follows: 1) the region corresponding to each of the geological units is constructed by selecting all the cells located beneath the modeled surface representing the upper limit of the unit; 2) subtraction of the cells corresponding to the underlying units is performed. The construction is thus realised in stratigraphic order, from the bottom (older units) to the top (younger units). |
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| The modeled geological units are presented in stratigraphic order, from the bottom (older) upward (more recent). Bedrock (R): undifferentiated. Lower glacial sediments (Ts): Old compact till with a thickness varying between 1 and 5 m, characterized by a gravelly diamicton with contiguous clasts. Old quaternary sediments (Q): Undifferentiated old quaternary sediments have been preserved in several valleys and can reach a thickness of several tens of meters. Upper glacial sediments (Ti): Till in quasi-continuous coverage over the entire study area. This unit may exceed 30 m in thickness. Undifferentiated glaciofluvial sediments (G): A set of subaerial and subaqueous outwash fan and ice contact facies. They are composed of a heterogeneous combination of sand and gravel with silty sand and even diamicton. Because these 3 types of sediments cannot be distinguished from one another in wells, they were grouped together for the purpose of 3D geological modeling. Their thickness can reach 40 m at the esker in the north of Valcatier. Glaciolacustrine deltaic sediments (Ld): With a thickness of less than 20 m, these sediments overly the glaciofluvial sequence in the area of the Montmorency river valley. Glaciomarine offshore fin sediments (Ma): Deep marine sediments consist mainly of clayey silt or silty clay deposited in topographic depressions. With a thickness of up to 50 m in wells, these clays constitute an aquitard underlying the Quebec aquifer. Glaciomarine intertidal sediments (Mi): Sediments consisting of silt and sandy silt and deposited in an intertidal or subtidal zone in sheltered bays or inlets. Thickness of 0.5 to 15 m. Glaciomarine deltaic and prodeltaic sediments (Md): Sands, gravelly sands and gravels that have all the sedimentological characteristics of a classic delta. Thickness up to 50 m. Glaciomarine littoral and nearshore sediments (Mb): Sand, sandy silt, gravelly sand and gravel with a thickness varying from 0.5 to 5 m. These sediments generally form a thin cover over the fine offshore sediments. Late glaciomarine coarse deltaic sediments (Md_gBV): Gravelly sand unconformably overlying the glaciomarine unit in the southern part of the model, in Quebec City lower town. Thickness from 1 to 5 m. Late glaciomarine deltaic sediments (Md_BV): Medium-grained deltaic sands with a thickness of more than 30 m upstream of the Saint-Charles River. Alluvial early fluvial terrace sediments (Ax): A unit composed of sand, sandy silt or gravel sometimes containing fragments of plants and deposited in areas overflowing the present river corridors. Thickness between 1 and 5 m. Early estuarine sediments (AT_sup_delta): A unit composed of silt, sandy silt, sand generally containing fragments of terrestrial and aquatic plants. Average thickness of 3 or 4 m, but varying from 2 to 10 m. Alluvial fluvial terrace sediments (At): A unit consisting of a varied set of sand, sandy silt, gravelly sand and gravel facies frequently containing plant fragments. Generally of small thickness (less than 3 m), this unit is located near the current rivers. Recent alluvial sediments (Ap): Located in the present river floodplains, the sediments are characterized by a heterogeneous composition of facies. These sands, sandy silts, gravelly sands and gravel often containing fragments of plants have a thickness of less than 3 m. Organic Sediment (O): Found in poorly drained depressions throughout the area. Generally of small thickness, they can nevertheless reach a thickness of 4 m. Characterized by peat soil; this unit is often located at the edge of a water body. Embankment, anthropogenic sediments (X): Significant anthropogenic significantly altered the natural landscape activities in the study area. Thus, the riverside of the St. Charles River, as well as those of the St. Lawrence River, have been greatly modified and their banks have been largely artificialized. It is possible to observe heterogeneous embankment deposits over a thickness of more than 20 m in the port of Quebec area. |
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| File identifier | be49f04e-cd37-015e-b245-8fd086b3a605 |
| Language | eng; CAN |
| Character encoding | utf8 |
| Hierarchical classification | dataset |
| Date | 2018-07-05 |
| Metadata standard | North American Profile of ISO 19115:2003 - Geographic information - Metadata |
| Version | CAN/CGSB-171.100-2009 |
| Constraints | |
| Update frequency | asNeeded |
| Reference System code | EPSG:26919 |
| Register | http://www.epsg-registry.org/ |
| Version | 6.14 |
| author |
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| Name | Francois Letourneau | ||||||
| Organisation | Government of Canada; Natural Resources Canada; Geological Survey of Canada - GSC Quebec | ||||||
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| Organisation | Government of Canada; Natural Resources Canada; Geological Survey of Canada | ||||||
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