Menu Close

Where do mafic igneous rocks form?

Where do mafic igneous rocks form?

1. INTRODUCTION. Mafic rocks that constitute the igneous oceanic crust are created at mid-ocean ridge seafloor spreading centers as a byproduct of partial melt from upwelling mantle. Through various parts of the spreading process, permeability can be generated in both the intrusive gabbros and extrusive basalts.

Where is mafic lava produced?

upper mantle
Mafic magma produces high volume, slow moving, effusive eruptions. It forms within the upper mantle, much deeper than felsic magma. Because of the depth, it is hotter and contains more high density materials, such as iron and magnesium.

Where does felsic magma generally form?

A. Intermediate and felsic magmas form around convergent margins with a subduction zone. 3. these volcanic mountain chains often form arc shapes, because that is the shape produced when a flat plate (tectonic plate) intersects a sphere (Earth).

Why is mid-ocean ridge magma mafic?

Consider that the magma erupting at mid-ocean ridges has moved maybe a mere ten km from its source, but whereas that source was Fe and Mg rich peridotite, the magma is slightly less. Thus, felsic material is added to the magma as mafic material is lost to fractional crystalization.

Is quartz a mafic mineral?

Mafic minerals are usually dark in color and have relatively high specific gravities (greater than 3.0). Common rock-forming mafic minerals include olivine, pyroxene, amphibole, biotite mica, and the plagioclase feldspars. Common felsic minerals include quartz, muscovite mica, and the orthoclase feldspars.

How do you tell if a rock is felsic or mafic?

In a widely accepted silica-content classification scheme, rocks with more than 65 percent silica are called felsic; those with between 55 and 65 percent silica are intermediate; those with between 45 and 55 percent silica are mafic; and those with less than 45 percent are ultramafic.

What are the 3 ways magma can form?

Magma is formed by both wet and dry melting processes. By melting different parts of the layers of the earth, basaltic, rhyolitic and andesitic magma will be formed.

Is magma felsic or mafic?

Felsic refers to silicate minerals, magma, and rocks which are enriched in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium. Felsic magma or lava is higher in viscosity than mafic magma/lava. Felsic rocks are usually light in color and have specific gravities less than 3.

Is andesite an intermediate?

Andesite is an extrusive rock intermediate in composition between rhyolite and basalt. Andesite lava is of moderate viscosity and forms thick lava flows and domes. The word andesite is derived from the Andes Mountains in South America, where andesite is common.

Which magma composition is most explosive?

Explosive eruptions are favored by high gas content and high viscosity (andesitic to rhyolitic magmas). Explosive bursting of bubbles will fragment the magma into clots of liquid that will cool as they fall through the air.

Where does mafic magma and felsic magma come from?

Mafic magma is liquid rock containing a high level of magnesium and iron. This differs from felsic magma that contains an abundance of silica and Click to see full answer In this regard, where does mafic magma come from?

What kind of rock is a mafic rock?

Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar. Chemically, mafic rocks are enriched in iron, magnesium and calcium and typically dark in color.

What’s the difference between felsic and mafic lava?

In contrast the felsic rocks are typically light in color and enriched in aluminium and silicon along with potassium and sodium. The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older basic rock class. Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava,…

How does magma get to the surface of the Earth?

The most familiar way for magma to escape, or extrude, to Earth’s surface is through lava. Lava eruptions can be “fire fountains” of liquid rock or thick, slow-moving rivers of molten material. Lava cools to form volcanic rock as well as volcanic glass. Magma can also extrude into Earth’s atmosphere as part of a violent volcanic explosion.