Magma Chambers and Crystallization Processes

The lecture covers magma processes, focusing on magma chambers and intrusions. It explains cumulates, crystallization, and the concept of closed system fractionation using the Scareguard intrusion as an example. The discussion includes sedimentary structures within magma chambers, highlighting the complexity of crystallization processes.

What is the primary role of magma chambers in volcanic systems?

• To create earthquakes

• To cool magma rapidly

• To store magma within the Earth's crust

• To transport magma to the Earth's surface

Which of the following is NOT a type of intrusion discussed in the lecture?

• Volcanoes

• Dikes

• Sills

• Lopoliths

In the context of cumulates, what does 'in-situ crystallization' refer to?

• Crystals forming at the bottom of a magma chamber

• Crystals dissolving in magma

• Crystals forming on the edges of a magma chamber

• Crystals floating to the top of a magma chamber

What is a key characteristic of an adcumulate rock?

• It is formed by rapid cooling

• It has a high density of trapped liquid

• It is composed almost entirely of cumulus grains

• It contains a high proportion of intercumulus material

What makes the Skye Guard intrusion a notable example in geology?

• It is located in a densely populated area

• It demonstrates closed system fractional crystallization

• It is the oldest known magma chamber

• It is the largest magma chamber on Earth

What is the primary reason for the systematic drop in anorthite content in plagioclase during crystallization?

• Introduction of new magma

• Cooling and crystallization process

• Decrease in pressure

• Increase in temperature

In the context of trace element fractional crystallization, why does chromium concentration fall during the crystallization of clinopyroxene?

• Chromium is removed by olivine

• Chromium is incompatible in clinopyroxene

• Chromium is highly compatible in clinopyroxene

• Chromium concentration remains constant

Which of the following best describes the behavior of magma chambers as closed systems?

• They frequently receive new magma

• They undergo significant crystal assimilation

• They are open to external influences

• They crystallize without new melt addition

What evidence supports the presence of sedimentary processes within magma chambers?

• Constant mineral composition

• Absence of mineral layering

• Presence of troughs and cross-bedding

• Uniform crystal distribution

How do density currents contribute to the crystallization process in magma chambers?

• They prevent crystal formation

• They distribute minerals towards the chamber's base

• They increase the temperature of the magma

• They cause uniform crystallization