Question

why do you think the ocean crust contains rocks that are denser than the rocks found on land?​

Answer 1

Explanation:

Because oceanic crust is made up of basalt. Basalt is a volcanic rock that wells up from the mantle at the mid ocean ridges to fill the gap left when a plate moves away from its neighbour.

This basalt cools to form new crust. Rich in silicon and magnesium, its density is 2.9 grams per cubic centimetre, Compare this with the continental crust,which is composed mainly of granite, an igneous rock rich in aluminiumand silicon. Its density is only 2.7 grams per cubic centimetre.

Answer 2

QUESTION:-

why do you think the ocean crust contains rocks that are denser than the rocks found on land?

ANSWER:-

• The ocean crust contains rocks that are denser because the Ocean lithosphere is mainly composed of basaltic where the upper levels are basalt and the lower levels are gabbro. The top levels have been substantiated with boreholes while the lower levels have been determined from transform failure sampling and comparisons with ophiolites.

• Whereas, rocks found on land are more complex and verges to be mainly of the composition of 'granitic'. This comprises granites but can also contain a lot of metamorphic rocks like gneiss and sediments. Sediments have lower density because of high pore space.

• Basalt is denser than granite which is found by the surveys on gravity where basalts and gabbros will arise as positive anomalies while granites and sedimentary basins will seem as negative anomalies. Hence, the ocean crust contains rocks that are denser than the rocks found on land.

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