The Rock Cycle and Plate Tectonics
Plate tectonics is the movement of the Earth's crust through convection currents that occur in the mantle. Divergent plate boundaries occur. Jump Ahead to Specific Tectonic Rock Cycle Stages. How Much Do You The cycle is the most theoretically abstract description of these rock relationships. Discovering how rocks are formed through plate tectonics. Comparing the formation of rocks. VOCABULARY: igneous; metamorphic; plate tectonics; rock cycle.
The rate of plate movements is directly related to the rate of igneous rock production. The most common igneous rock type is basalt and it makes up the bulk of oceanic plates. Basalt is formed at divergent plate boundaries the rate of sea floor spreading and, consequently, volcanism.
Discovering How Rocks are Formed by Plate Tectonics
This is a drawing of seafloor spreading. Image copyright by the American Geophysical Union. Further electronic distribution is not allowed. The amount of weathering and erosion of rocks is in part controlled by uplift.
Uplift occurs when areas of the crust move up due to plate tectonic movements. Rocks will be more likely to erode if they have been uplifted and are essentially unstable and out of balance with the surroundings. From a scientific viewpoint there is no "progress", there is just change.
How Does Plate Tectonics Affect the Rock Cycle? | Sciencing
But the earth is an open, dissipative system, and it does evolve, as the Wilson Cycles illustrates. Our work is to understand and explicate the processes leading to that evolution.
So, if we are looking for one simple ideal model of how the earth operates, avoiding all the technical details, we need a different model than the basic rock cycle. The Tectonic Rock Cycle is such a model below.
Here we see in one diagram a complete summary of the processes that lead to the evolution of the physical earth. Just look for the major paths of flow through the cycle, following the arrows. Take a highlighter and draw a line showing those major paths.
- What is the relationship between the rock cycle and plate tectonics?
The path forms a question mark shape, and it does not cycle back on itself completely. Even sedimentary processes fractionate the rocks chemistry. Observe that the sedimentary rocks in the yellow box when metamorphosed to the melting state result in an igneous rock low on the reaction series. Thus, the tectonic rock is operating like the drawings below right. The basic rock cycle on the left just goes round and round without getting anywhere.
Early Greeks ascribed earthquakes to the god Poseidon expressing his wrath, an explanation that accounted for their unpredictability. The Navajo view processes on the surface as interactions between opposite but complementary entities: Most 17th century European Christians believed that the Earth was essentially unchanged from the time of creation.
When naturalists found fossils of marine creatures high in the Alps, many devout believers interpreted the Old Testament literally and suggested that the perched fossils were a result of the biblical Noah's flood.
Uniformitarianism In the mids, a Scottish physician named James Hutton began to challenge the literal interpretation of the Bible by making detailed observations of rivers near his home. Every year, these rivers would flood, depositing a thin layer of sediment in the floodplain. It would take many millions of years, reasoned Hutton, to deposit a hundred meters of sediment in this fashion, not just the few weeks allowed by the Biblical flood.
Hutton called this the principle of uniformitarianism: Processes that occur today are the same ones that occurred in the past to create the landscape and rocks as we see them now. By comparison, the strict biblical interpretation, common at the time, suggested that the processes that had created the landscape were complete and no longer at work.
The Rock Cycle: Uniformitarianism and Recycling
This image shows how James Hutton first envisioned the rock cycle. Hutton argued that in order for uniformitarianism to work over very long periods of time, Earth materials had to be constantly recycled. If there were no recycling, mountains would erode or continents would decayin Hutton's termsthe sediments would be transported to the sea, and eventually the surface of the Earth would be perfectly flat and covered with a thin layer of water.
Instead, those sediments once deposited in the sea must be frequently lifted back up to form new mountain ranges.
The Rock Cycle and Plate Tectonics
Recycling was a radical departure from the prevailing notion of a largely unchanging Earth. As shown in Figure 1, Hutton first conceived of the rock cycle as a process driven by Earth's internal heat engine. Heat caused sediments deposited in basins to be converted to rock, heat caused the uplift of mountain ranges, and heat contributed in part to the weathering of rock.
While many of Hutton's ideas about the rock cycle were either vague such as "conversion to rock" or inaccurate such as heat causing decayhe made the important first step of putting diverse processes together into a simple, coherent theory. Hutton's ideas were not immediately embraced by the scientific community, largely because he was reluctant to publish.The Rock Cycle and Plate Tectonics
He was a far better thinker than writer — once he did get into print infew people were able to make sense of his highly technical and confusing writing to learn more about Hutton and see a sample of his writing, visit the Resources for this module. His ideas became far more accessible after his death with the publication of John Playfair's "Illustrations of the Huttonian Theory of the Earth" and Charles Lyell 's "Principles of Geology" By that time, the scientific revolution in Europe had led to widespread acceptance of the once-radical concept that the Earth was constantly changing.
A far more complete understanding of the rock cycle developed with the emergence of plate tectonics theory in the s see our Plate Tectonics I module.