The focus of the research conference I attended last week was to revisit the mechanisms and processes that are responsible for getting terrigenous (i.e., continentally-derived) sediment from river mouths and coastal areas out to the shelf or deep-marine basins.
When it comes to sediment coarser than mud, sediment gravity flows are one of the key processes for transporting material into the deep sea. These are bottom-hugging sediment-laden flows that carve canyons, create channel-levee morphology, build submarine fans, and so on.
I've posted numerous times about the products of sediment gravity flow processes ... that is, the sediments or rocks. But, these deposits are really only recording the last moments of the life of a sediment gravity flow ... they are the depositional processes. What about the processes at the beginning of a flow?
Considering how these flows begin falls under the term initiation mechanisms. We do not have a very good understanding of these processes. Firstly, observation of submarine processes, in general, is extremely challenging. Secondly, the occurrence of sediment gravity flow events is common over geologic time scales, but infrequent over human time scales. So, even if we could observe them, we might have to wait a couple hundred years for one to occur.
This conference was aimed at revisiting the ideas about initiation mechanisms. This is a fascinating subject because it brings together geologists who focus on preserved products in the rock record with oceanographers who study and monitor active processes in the modern.
My next post (another day or two) will go into a little more detail about specific initiation mechanisms and examples.
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