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Zorluk: OrtaInternal and External Structure of the Earth

Geological analysis of the Earth's crust reveals distinct compositional and physical differences between continental and oceanic sectors. Which of the following statements accurately describes the relationship between the sial and sima layers?

  1. Sial is rich in silica and aluminium, forming a lighter granitic layer that floats upon the denser basaltic sima layer composed of silica and magnesium.Cevap
  2. B
    Sial is composed mainly of ocean-floor marine sedimentary deposits, making it denser than the underlying basaltic sima layer.
  3. C
    Sima is formed through the down-slope mass movement of weathered sialic rock fragments accumulating along coastal margins under gravity.
  4. D
    Sial and sima together form the metallic barysphere, which directly surrounds the fluid outer core of the Earth.

Cevap

Sial is rich in silica and aluminium, forming a lighter granitic layer that floats upon the denser basaltic sima layer composed of silica and magnesium.
The sialic layer (silica and aluminium) forms the lighter continental crust with an average density of 2.7 g/cm³, resting directly above the denser simaic layer (silica and magnesium, 3.0 g/cm³) which constitutes the oceanic crust and continuous lower crustal foundation.

Adım Adım Çözüm

1
Analyze the chemical composition denoted by the names sial and sima.
Sial derives from Silica and Aluminium (granitic composition), whereas Sima derives from Silica and Magnesium (basaltic composition).
These chemical elements form the essential constituent minerals of the upper and lower crust.
2
Determine the relative density and structural positioning of these layers within the lithosphere.
Sial has an average density of 2.7 g/cm³ and forms the upper continental crust, while sima has an average density of 3.0 g/cm³ and forms the oceanic floor beneath sial.
Principle of isostasy dictates that lighter granitic rocks float on top of denser basaltic substrates.

Anahtar Kavram

Composition and structural characteristics of the Earth's crust (Sial and Sima)
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Konular

Internal and External Structure of the Earth

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