Sentences with phrase «igneous crust»

Not exact matches

Most of the ocean's salts were derived from gradual processes such the breaking up of the cooled igneous rocks of the Earth's crust by weathering and erosion, the wearing down of mountains, and the dissolving action of rains and streams which transported their mineral washings to the sea.

Mars has been viewed as an almost entirely basaltic planet, with igneous rocks that are dark and relatively dense, similar to those forming the Earth's oceanic crust, Wiens noted.

The plate failed to split completely, but geologists think that the event left scars below the NMSZ: a buried rift zone, where the rocks are weak and fractured, over plutons — blobs of dense igneous rock — that themselves rose from an upwelling of unusually dense lower crust.

The textbook explanation is that the Moho draws the line between the crust and the mantle: a demarcation between familiar igneous surface rocks - such as granites, basalts and gabbros - and those of the interior peridotites.

For a start, it would mean the igneous ocean crust is far more variable in thickness and in structure than previously recognised.

Earth and Venus should have had sufficient inner heat to remelt some of its surface basalt to form a range of igneous rocks called granites or «granitoids,» which are coarse - grained blends of lighter minerals (including quartz, feldspar, and mica that are common in Earth's crust but rarer in the smaller planetsimals).

So, given that the radius of the Earth is over 6000 kms, and granite melts at around 1250 C, the relatively viscous crust is at most 45 km thick on average, (below the melting point of igneous granite).