Source-Sink Systems
Wednesday, 5. August 2009, 07:06:17
Geology is first and foremost what you see in the field, but now and then you need to theorise. I cannot imagine any pleasure in sedimentology without plate tectonics, and that is probably a main reason why I (occasionally assumed to be a sedimentologist) am fascinated by plate tectonics. That is to me the start of the so-called rock cycle. Plate tectonics give rise to uplift - to building of (high) mountains. The uplifted rocks weather and erode, and the weathered and eroded material is either deposited in situ or transported away.
The simplest case of sediment transport is by gravity. Rock falls and landslides. Scree deposits are a regular sight in mountainous areas (where they make climbing and walking difficult), but they are rarely seen in old sediments.
Transport of particles in water is however the most important of all sediment transport mechanisms, not only by streams and rivers but also by ocean currents.
The next important transporting medium is air. Loess is a good example of airborne deposits, with very fine-grained particles. In a desert with practically no rainfall, it is a pleasure to see what wind can do with sands.
Maybe we tend to forget ice as a sediment transport medium, although in the region where I was born, you cannot miss it with all the moraines from the Ice Age. Glaciers act much like a conveyor belt carrying debris from the top of the glacier to the bottom where it deposits it in end moraines. Glacial erratics
can also be extremely spectacular.
The source-to-sink system comprises all areas that contribute to erosion, transportation and deposition of sediments within an erosional-depositional system - from catchment headwater to deep-marine basin floor fan. You can divide the source-to-sink system into four segments as done in a recent paper in Basin Research.
Here is an illustration from that paper
showing the segments: catchment, shelf, slope, and basin floor. The segments are related so that long-term modification (on geological time scales) by erosion and deposition in one segment will affect one or several remaining segments, causing lengthening and flattening of the segments and overall development of the entire system. The basin floor (deep ocean floor) is the ultimate sink (in the sedimentary record). Later, however, the buried sediments can be reused via the rock cycle and plate tectonics, so that they can be uplifted to build new mountains as sedimentary, metamorphic or fully re-melted igneous rocks.
From cradle to the grave - from erosion to deposition - from source to sink. That is indeed a basic concept.
Reference:
Sømme et al.
Relationships between morphological and sedimentological parameters in source-to-sink systems: a basis for predicting semi-quantitative characteristics in subsurface systems
Basin Research (2009) 21, number 4 of August 2009, pp. 361–387
doi: 10.1111/j.1365-2117.2009.00397.x
The simplest case of sediment transport is by gravity. Rock falls and landslides. Scree deposits are a regular sight in mountainous areas (where they make climbing and walking difficult), but they are rarely seen in old sediments.
Transport of particles in water is however the most important of all sediment transport mechanisms, not only by streams and rivers but also by ocean currents.
The next important transporting medium is air. Loess is a good example of airborne deposits, with very fine-grained particles. In a desert with practically no rainfall, it is a pleasure to see what wind can do with sands.
Maybe we tend to forget ice as a sediment transport medium, although in the region where I was born, you cannot miss it with all the moraines from the Ice Age. Glaciers act much like a conveyor belt carrying debris from the top of the glacier to the bottom where it deposits it in end moraines. Glacial erratics
can also be extremely spectacular.
The source-to-sink system comprises all areas that contribute to erosion, transportation and deposition of sediments within an erosional-depositional system - from catchment headwater to deep-marine basin floor fan. You can divide the source-to-sink system into four segments as done in a recent paper in Basin Research.
Here is an illustration from that paper
showing the segments: catchment, shelf, slope, and basin floor. The segments are related so that long-term modification (on geological time scales) by erosion and deposition in one segment will affect one or several remaining segments, causing lengthening and flattening of the segments and overall development of the entire system. The basin floor (deep ocean floor) is the ultimate sink (in the sedimentary record). Later, however, the buried sediments can be reused via the rock cycle and plate tectonics, so that they can be uplifted to build new mountains as sedimentary, metamorphic or fully re-melted igneous rocks.
From cradle to the grave - from erosion to deposition - from source to sink. That is indeed a basic concept.
Reference:
Sømme et al.
Relationships between morphological and sedimentological parameters in source-to-sink systems: a basis for predicting semi-quantitative characteristics in subsurface systems
Basin Research (2009) 21, number 4 of August 2009, pp. 361–387
doi: 10.1111/j.1365-2117.2009.00397.x
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