What is the cause of negative magnetic marine anomalies? Are these anomalies sim

Question

What is the cause of negative magnetic marine anomalies? Are these anomalies similar on both sides of the ridge crest? Note the figure below, how would the age of the rock change going from A to B? Note the figure to the right. If the distance from A to B is 400 km and a sample of oceanic crust at B is found to be 40 million years old, what is the seafloor spreading rate? 1. 2. What technology is being employed to measure rates directly in real time? Some recent rift valleys are found on the east side of what continent? A trench system, accretionary wedge, forarc basin and _____ are common features at ocean-ocean convergence zones. Mountain belts adjacent and parallel to the coast line of a continent are indicative of what type of boundary _____. What are some other forcing mechanisms that might be involved in plate motion besides convection?

Explanation / Answer

1. magma rises from the interior of the earth and crystallized and formed rock ,at the time of rock formation rock material preserve the current magnetic field direction with itself. magnetic field direction of the earth changed alternatively after some timeperiod. if the north seeking magnetization point towards the earth's magnetic north pole , the rock is said to have normal magnetization . in other case if the north seeking magnetization points towards the present magnetization points towards the present day south magnetic pole , the rock has called negative magnetization.

so negative magnetic marine anamolies shows that at the time of that rock formation magnetic direction of the earth was reversed.

2. at the divergent plate boundary magma comes from the interior of the earth and rocks formed new formed rock preserve the current magnetic direction and when new magma comes it splits into two parts and those parts goes into different directions. these splited parts of the rock will be equi distance from the open source of the magma.

so on equi distance anamolies will be same

3. on the location of A magma genrates continuously and new rock are forming so in A to B direction rocks are new to older.

distance from A to B = 400 km =4 *107 cm

age of oceanic crust at B = 40 million years old = 4 *107    years old

rate of sea floor spreading = 4 *107 / 4 *107      = 1 cm/year

4. radio metric dating is used for the direct measure rates directly in time.

5. some recent rift valleys like east african rift valley are found on the east side of Asian continent.

6. A trench system , accretionary wedge , forearc basin and chain of island arcs are common features at ocean ocean convergence zone.

at the convergent boundary one plates sinks into other plate and melts, this melting plate material affects the other plate and partial melting has been taken place into other plate, this melt comes to the surface and formed the chains of volcanoes. this is called island arcs.

7. Mountain belt adjacent and parallel to the coast line of a continent are indicative of divergent of constructive plate boundary. because in this type of plate boundary magma comes and forms the rocks via process of crystallization and cooling.

8. other forcing mechanism for the movement of plates are orogeny and the isostatic imbalance between oceanic plate and continental plate because they made by different composition and their density and thickness are also different from each other.

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.