s3 Flashcards
(39 cards)
the thermal energy that was generated during the formation and early evolution of the Earth.
Primordial Heat from Planetary Formation
The process of planet formation involves the collision and aggregation of smaller bodies (planetesimals). The kinetic energy from these collisions was converted into heat.
Accretion
As the Earth formed, gravitational forces caused it to compress. The conversion of gravitational potential energy into thermal energy generated significant heat.
Gravitational Compression
The decay of short-lived radioactive isotopes (such as aluminum-26) during the early stages of Earth’s formation contributed to the initial heat.
Radioactive Decay
also known as gravitational contraction or self-compression, is the process by which a celestial body generates heat due to the conversion of gravitational potential energy into thermal energy.
Process converting gravitational potential energy into thermal energy during celestial body formation.
Gravitational Compression
Accretion of smaller bodies into a larger body increases mass and gravitational force.
Formation Process
The potential energy of particles transforms into thermal energy through friction and collisions.
Conversion of Energy
Generated by the movement of tectonic plates.
Heat from Friction Due to Plate Movements
Significant heat produced in the planet’s interior during early formation stages.
Heat Generation
Plates of the Earth’s crust move over the semi-fluid asthenosphere.
Tectonic Activity
Plates grinding against each other at boundaries (convergent, divergent, and transform) generate frictional heat
Frictional Heat
Heat generated within the Earth’s interior is transferred to the surface through three main mechanisms: conduction, convection, and radiation.
Heat Transfer Mechanisms within Earth
One plate being forced under another generates significant friction and heat.
Subduction Zones
Direct Heat Transfer: Heat moves through solid materials like rocks.
Conduction
Fluid Movement: Heat transfer through the movement of semi-fluid rock in the mantle.
Convection
Localized Heat Sources: Areas of volcanic activity not directly associated with plate boundaries
.
Hotspots
- Heat
- Pressure
- Volatiles
Conditions Required for Magma Formation
For rocks to melt and form magma, temperatures must be high enough to overcome the bonds holding the minerals together.
Heat
Residual heat from the planet’s formation.
Primordial Heat
Continuous heat production from the decay of radioactive isotopes.
Radioactive Decay
Generated by the movement and deformation of tectonic plates.
Frictional Heating
- Decompression Melting
- Flux Melting
- Heat-Induced Melting
Processes Leading to Magma Formation
Heat-induced melting occurs when the temperature of the mantle or crust increases due to tectonic processes such as mantle plumes or hotspots.
Heat-Induced Melting
Occurs when there is a decrease in pressure as mantle rocks ascend. This process is common at divergent plate boundaries, such as mid-ocean ridges, where tectonic plates move apart. As the pressure decreases, the mantle material rises and partially melts, forming basaltic magma.
Decompression Melting