igneous rocks in the field

Question 1

how do intrusive rocks get on surface

Answer 1

magma emplacement into crust

tectonic driven process of magma rising, filling in the space

ductile country rock deformation

lateral displacement of surround rock by faulting or folding

Question 1

2 types of igneous bodies

Answer 1

discordant
igneous rock bodies cutting across pre-existing rock bed

concordant
igneous rock bodies cutting parallel pre-existing rock bed

Question 2

discordant igneous body example

Answer 2

dykes

sheetlike body of igneous rock which cuts across country rock

Question 3

concordant igneous body example

Answer 3

sills

tabular bodies of igneous rocks which cut parallel to country rock

Question 4

baked margin

Answer 4

igneous body locally contact metamorphoses surrounding country rock due to magma heat

Question 5

chilling margin

Answer 5

igneous body has quickly cooled at the margins due to temperature difference forming a “rind” of finer-grained igneous rock compared to the texture in the middle of the unit

if contact water you find a glassy quench-cooled texture and some alteration