A priori, the concept of imbrication It may not sound like anything to you. We go to the field of geology, where there are various phenomena that can occur continuously and give us a lot of information. Let us put ourselves within the range of sedimentary structures of continental origin. It is here where we find the interweaving of the conglomerates. These structures have a rather curious implication and can give us paleoenvironmental information. The imbrication has studies of the sediments that come from the Cenozoic and can be very useful for obtaining geological information about an area, in addition to being related to climatic and tectonic events, as well as the way in which different types of rocks are formed.
In this article we are going to tell you everything you need to know about nesting.
What is nesting
Imbbrication is nothing more than sedimentation that occurs in high and low energy river systems. Its determination is aimed at the geographical reconstruction, prevention and mitigation of the risks presented by some exogenous processes in continental areas. In order to study this nesting, a stratigraphic record is needed that It helps to be able to understand all the geological events that have taken place in that same area. To learn more about these events, you can consult the article on historical geology and how they influence sedimentary imbrication in geology.
This interlocking of clasts or conglomerates can provide us with valuable information about how a particular sediment was formed. We could say that this interlocking is the arrangement of blocks within a sediment, or that it causes the major axes to lie approximately parallel and at a certain angle to the horizontal pointing in the direction of the current. As mentioned before, these are sediments that have been modified by the action of a river.
To better understand this, let's use the example of a water flow that carries gravel-sized or larger materials as bedload. We recall that sediment transport can occur in several ways. The first was creeping: this involves the transport of larger sediments that gradually move along the ground by creeping. The second was saltation: saltation is the transport of slightly smaller sediments that are heavy enough to be moved only by small jumps.
Finally, we had two types of transport for those smaller sediments. One was flotation and the other was dissolution. Flotation, as its name suggests, is the transport of a given material through floating in water. Dissolution occurs when the particles are so small that they are dissolved in the water.
That said, we speak of clast nesting when This bottom load is the size of gravel or larger. These clasts have a longer axis than the others, so when the water current loses strength, they remain deposited on the bottom and are placed in the position that, hydrodynamically, is more stable.
How to recognize nesting
It turns out that sediments transported by the water flow settle in the most stable position. If the clasts were placed on a countercurrent slope, the force of the current would most likely overturn them again. This recognition of imbrication can help us determine whether certain slopes and geological morphologies once had a river course.
The result of the placement of the clasts in the inclination of the stream makes there is a packing of the components of the material that is quite characteristic.
When we visualize a slope where there has been a river course we can see the following characteristics:
- The sequence of clasts and segmented materials usually has a grain-decreasing sequence. That is, the clasts that are larger are closer together at the base than those that are closer to the top. This is because the force of the river course is not so strong as to be able to transport the larger sediments to the top.
- We can find very little space between two clasts, so it is understood that they have a very scarce matrix. This is, that the materials have been deposited together. To better understand this process, we recommend you read about hydrogeology, which addresses the processes that affect sedimentary interlocking in geology.
- Normally the edges are well rounded since the water has been eroding a large part of them. It is rare to find some sharp edges.
- As the clasts are imbricated, we can find them with an inclination in the same direction that is the one that reveals the direction of the water in the river course.
Imbbricated clasts information
This entire analysis of clasts deposited in a particular manner gives us a lot of information about how these sediments were deposited. First, we must consider the size selection and the clear stratification observed. This indicates that the transport forces may have been turbulent flow. If the clasts are also rounded, it indicates that the river course was relatively intense and long.
The interlocking of the clasts reveals the direction of the flow of the river course. By knowing the direction in which the sediments are placed, we can know which direction the water flow was leading. The sequence of sediments in decreasing grain position indicates that the river was losing transport capacity over time. It also suggests that there have been some flood events that have transported coarser material and excavated small channels between the sandy silts of previous deposits.
If we look closely, the conglomerates are linked to all the climatic and tectonic variations that occur over time. It's also a combination of both. Tectonic processes are responsible for the creation of mountain ranges and the uplift and subsidence of areas bordered by faults. However, climatic effects are what give rise to these alluvial plains and the expansion of river banks.
As you can see, thanks to the interlocking of clasts, we can learn a lot about what existed long ago. I hope this information will help you learn more about interlocking.
