Why is basalt found on the ocean floor?

Why is basalt found on the ocean floor?

Basalt is a type of lava that the rocks of the mantle make when they start to melt. Once formed in the deep crust, basalt magma wants to rise, and at the center of the mid-ocean ridge, it oozes onto the seafloor, where it rapidly solidifies in the ice-cold water in the form of lava pillows.

Is the ocean floor made of basalt?

Basalt is considered a mafic silicate rock. Among other characteristics, mafic minerals and rocks are generally dark in color and high in specific gravity. As it turns out, most of the ocean floor is basalt, and most of the continents are granite.

How do scientists determine the age of a seafloor basalt?

Scientists can determine the age of the seafloor by examining the changing magnetic field of our planet. As rocks crystallise from lava at the ridges, they literally record the magnetic field of the Earth at the time of their creation.

Is the ocean floor made of igneous rock?

Basalt is the type of igneous rock that makes up the ocean floor. In the middle of the Atlantic Ocean is a divergent plate boundary. The chemical composition of this magma generates mafic silicate rock, which means it contains predominately silicon, oxygen, iron and magnesium.

How were igneous rocks formed?

Igneous rocks (from the Latin word for fire) form when hot, molten rock crystallizes and solidifies. The melt originates deep within the Earth near active plate boundaries or hot spots, then rises toward the surface.

Which scientist discovered the ocean floor?

Harry Hess
Harry Hess was a geologist and Navy submarine commander during World War II. Part of his mission had been to study the deepest parts of the ocean floor. In 1946 he had discovered that hundreds of flat-topped mountains, perhaps sunken islands, shape the Pacific floor.

How did scientists date sea floor rocks?

To confirm the ages obtained with magnetic records, and get an absolute age of the seafloor, scientists use the radioactive dating technique. When the lava solidifies at the ridges to form the new seafloor, radioactive elements coming from the mantle are trapped in it.

What type of rock are sea floors made up of?

Basaltic Rocks
Basaltic Rocks The top layer of the sea floor is primarily composed of about 50 % basalt, which is the most common type of volcanic rock to be erupted.

How basalt is formed?

Basalts are usually dark gray to black color. Basalts are formed by the rapid cooling of basaltic lava, equivalent to gabbro-norite magma, from interior of the crust and exposed at or very close to the surface of Earth. These basalt flows are quite thick and extensive, in which gas cavities are almost absent.

How did scientists discover the spreading of the ocean floor?

Geomagnetic Reversals The magnetism of mid-ocean ridges helped scientists first identify the process of seafloor spreading in the early 20th century. Basalt, the once- molten rock that makes up most new oceanic crust, is a fairly magnetic substance, and scientists began using magnetometer s to measure the magnetism of the ocean floor in the 1950s.

How are the ages of seafloor rocks determined?

The age of seafloor rocks increases from the ridge crest to rocks the farthest from the ridges. Still, the rocks of the ocean basins are much younger than most of the rocks of the continents. Describe the pattern the magnetic stripes make in the ocean floor.

Where does most of the basalt on Earth come from?

Most of the basalt found on Earth was produced in just three rock-forming environments: 1) oceanic divergent boundaries, 2) oceanic hotspots, and 3) mantle plumes and hotspots beneath continents. The images on this page feature some of these basalt-forming environments.

How are magnetic patterns found on the seafloor?

Data from magnetometers dragged behind ships looking for enemy submarines in WWII discovered amazing magnetic patterns on the seafloor. Rocks of normal and reversed polarity are found in stripes symmetrically about the mid-ocean ridge axis.