Grain size fractionation by process‐driven sorting in sandy to muddy deltas
Abstract Modern and ancient analogues are often consulted by geologists to help understand subsurface systems. While modern analogues provide information on the areal relationship between facies, ancient systems provide detailed data on the vertical facies variations, typically along a two‐dimension...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Wiley
2020-02-01
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| Series: | The Depositional Record |
| Subjects: | |
| Online Access: | https://doi.org/10.1002/dep2.85 |
| _version_ | 1818039798199222272 |
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| author | Helena van derVegt Joep E.A. Storms Dirk‐Jan R. Walstra Kjetil Nordahl Nick C. Howes Allard W. Martinius |
| author_facet | Helena van derVegt Joep E.A. Storms Dirk‐Jan R. Walstra Kjetil Nordahl Nick C. Howes Allard W. Martinius |
| author_sort | Helena van derVegt |
| collection | DOAJ |
| description | Abstract Modern and ancient analogues are often consulted by geologists to help understand subsurface systems. While modern analogues provide information on the areal relationship between facies, ancient systems provide detailed data on the vertical facies variations, typically along a two‐dimensional outcrop. Combining data from modern and ancient systems effectively requires translating areal morphology, which is often still evolving, to the related sediments preserved in three dimensions. Process‐based models simulate both depositional processes while preserving stratigraphy. These models can be employed to unravel the relationship between sediment supply and preserved deposits in natural systems and to help integrate field data. Four synthetic deltas were modelled using different sediment supply compositions, from coarse to very fine sand systems. The resultant sedimentary deposits are classified into architectural elements, and the grain size composition of each architectural element is studied over time. Facies that are extensive in their horizontal dimensions are often less abundant in three‐dimensional preserved deposits. Between deltas, grain size compositions of a specific architectural element type (e.g. mouth bars) are more similar than their corresponding sediment supply compositions. This is due to selective deposition of grain size classes across each architectural element type. This selective deposition causes overrepresentation of the same range of grain sizes, even for systems with different sediment supply compositions. When a particular supply composition does not contain enough of the overrepresented grain size class for a particular architectural element, that element will be under‐supplied and constitute a smaller proportion of the overall delta deposits. It is imperative to account for over‐representation of grain size classes in particular architectural elements when estimating palaeo‐sediment supply, delta architecture and morphology from field data. Even when data availability/accessibility does not allow the inclusion of distal deposits in field studies, process‐based simulations can contribute valuable information on sediment sorting patterns in three dimensions. |
| first_indexed | 2024-12-10T08:04:21Z |
| format | Article |
| id | doaj.art-8f4e3bbd93334ce18be5b933578a0e45 |
| institution | Directory Open Access Journal |
| issn | 2055-4877 |
| language | English |
| last_indexed | 2024-12-10T08:04:21Z |
| publishDate | 2020-02-01 |
| publisher | Wiley |
| record_format | Article |
| series | The Depositional Record |
| spelling | doaj.art-8f4e3bbd93334ce18be5b933578a0e452022-12-22T01:56:43ZengWileyThe Depositional Record2055-48772020-02-016121723510.1002/dep2.85Grain size fractionation by process‐driven sorting in sandy to muddy deltasHelena van derVegt0Joep E.A. Storms1Dirk‐Jan R. Walstra2Kjetil Nordahl3Nick C. Howes4Allard W. Martinius5Department of Geoscience and Engineering Delft University of Technology Delft The NetherlandsDepartment of Geoscience and Engineering Delft University of Technology Delft The NetherlandsDeltares Delft The NetherlandsEquinor Trondheim NorwayMathWorks Natick MassachusettsDepartment of Geoscience and Engineering Delft University of Technology Delft The NetherlandsAbstract Modern and ancient analogues are often consulted by geologists to help understand subsurface systems. While modern analogues provide information on the areal relationship between facies, ancient systems provide detailed data on the vertical facies variations, typically along a two‐dimensional outcrop. Combining data from modern and ancient systems effectively requires translating areal morphology, which is often still evolving, to the related sediments preserved in three dimensions. Process‐based models simulate both depositional processes while preserving stratigraphy. These models can be employed to unravel the relationship between sediment supply and preserved deposits in natural systems and to help integrate field data. Four synthetic deltas were modelled using different sediment supply compositions, from coarse to very fine sand systems. The resultant sedimentary deposits are classified into architectural elements, and the grain size composition of each architectural element is studied over time. Facies that are extensive in their horizontal dimensions are often less abundant in three‐dimensional preserved deposits. Between deltas, grain size compositions of a specific architectural element type (e.g. mouth bars) are more similar than their corresponding sediment supply compositions. This is due to selective deposition of grain size classes across each architectural element type. This selective deposition causes overrepresentation of the same range of grain sizes, even for systems with different sediment supply compositions. When a particular supply composition does not contain enough of the overrepresented grain size class for a particular architectural element, that element will be under‐supplied and constitute a smaller proportion of the overall delta deposits. It is imperative to account for over‐representation of grain size classes in particular architectural elements when estimating palaeo‐sediment supply, delta architecture and morphology from field data. Even when data availability/accessibility does not allow the inclusion of distal deposits in field studies, process‐based simulations can contribute valuable information on sediment sorting patterns in three dimensions.https://doi.org/10.1002/dep2.85Grain sizemouth barriver delta architecturesorting |
| spellingShingle | Helena van derVegt Joep E.A. Storms Dirk‐Jan R. Walstra Kjetil Nordahl Nick C. Howes Allard W. Martinius Grain size fractionation by process‐driven sorting in sandy to muddy deltas The Depositional Record Grain size mouth bar river delta architecture sorting |
| title | Grain size fractionation by process‐driven sorting in sandy to muddy deltas |
| title_full | Grain size fractionation by process‐driven sorting in sandy to muddy deltas |
| title_fullStr | Grain size fractionation by process‐driven sorting in sandy to muddy deltas |
| title_full_unstemmed | Grain size fractionation by process‐driven sorting in sandy to muddy deltas |
| title_short | Grain size fractionation by process‐driven sorting in sandy to muddy deltas |
| title_sort | grain size fractionation by process driven sorting in sandy to muddy deltas |
| topic | Grain size mouth bar river delta architecture sorting |
| url | https://doi.org/10.1002/dep2.85 |
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