how is magnesium supported the theory of seafloor spreading?
Magnesium plays a significant role in supporting the theory of seafloor spreading through several observations and analyses. Here are the steps explaining how magnesium supports this theory:
1. Understanding the Earth's crust: The Earth's crust is made up of several tectonic plates that float on the semi-fluid layer below called the asthenosphere. These plates are composed of various types of rock, including basaltic oceanic crust.
2. Analyzing basaltic oceanic crust: Basaltic rocks found in the oceanic crust contain a high concentration of magnesium compared to other elements. This composition is due to the crystallization of magma at mid-ocean ridges, where new oceanic crust is formed.
3. Identifying the mid-ocean ridge system: Scientists documented the presence of extensive underwater mountain ranges called mid-ocean ridges, such as the Mid-Atlantic Ridge. These ridges are marked by volcanic activity and heat escaping from the Earth's mantle.
4. Studying magnetism and magnetic anomalies: Scientists discovered that the rocks formed at mid-ocean ridges have a striped pattern of magnetic polarity. These stripes run parallel to the ridge axis and can be detected using magnetic instruments. These patterns were consistent with the Earth's magnetic field reversals over time.
5. Collecting magnetic data: By using ships equipped with magnetometers, scientists surveyed the ocean floor and obtained magnetic data along with bathymetric (depth) data. They observed magnetic anomalies, where alternating stripes of normal and reversed magnetic polarity were recorded.
6. Correlating magnetic anomalies: The magnetic anomalies found along the mid-ocean ridges were similar on both sides of the ridge. This suggested that the seafloor was spreading symmetrically, with new crust continuously forming at the ridges.
7. Connecting magnesium and magnetic anomalies: Scientists made a link between the high-magnesium basaltic rocks formed at the mid-ocean ridges and the alternating magnetic anomalies on either side of these ridges. The Basaltic rocks with higher magnesium content recorded different magnetic properties than those with lower magnesium content.
8. Establishing the Vine-Matthews-Morley hypothesis: Scientists Vine, Matthews, and Morley proposed that the magnetic anomalies observed along the ridges resulted from periodic reversals of Earth's magnetic field. As magma rises at the ridges, it cools down and locks in the magnetic field direction. When new crust forms, it preserves the specific magnetic polarity of that time, resulting in the alternating magnetic anomalies.
In summary, the high concentration of magnesium in basaltic oceanic crust provides evidence that new crust is continually formed at mid-ocean ridges. The symmetric magnetic anomalies found on either side of the ridges correlate with the alternating magnetic field reversals, supporting the theory of seafloor spreading.
Magnesium plays a critical role in supporting the theory of seafloor spreading. This theory suggests that new oceanic crust is formed at mid-ocean ridges and spreads apart, pushing the older crust away from the ridge.
Now, when magma rises to the surface at mid-ocean ridges, it solidifies and forms new rocks. These rocks contain minerals, including magnesium-rich minerals such as olivine and pyroxene.
As the new oceanic crust is formed at these ridges, it pushes the existing crust away, creating a symmetrical pattern of magnetic anomalies on either side of the ridge.
Here's where the role of magnesium comes into play. The magnesium content in the minerals formed at mid-ocean ridges is higher compared to the magnesium content in the older oceanic crust. When these rocks solidify, they record the magnetic field direction of Earth at that time.
Scientists have discovered that the Earth's magnetic field periodically flips, meaning it changes its polarity over time. By analyzing the magnetic anomalies recorded in the rocks, scientists found a pattern of alternating "normal" and "reversed" magnetism on either side of the mid-ocean ridges.
This discovery supported the theory of seafloor spreading, as it indicated that the oceanic crust was being continuously created at the ridges and moving away from them. Since the magnetic anomalies were symmetrical on both sides of the ridge, it indicated a process of spreading.
In summary, the higher magnesium content in the newly formed rocks at mid-ocean ridges and the symmetrical pattern of magnetic anomalies on either side of the ridges provide strong evidence for seafloor spreading. Analyzing the magnetic properties of these rocks helps scientists understand the movement and formation of the oceanic crust.