mesozoic plate tectonics

supercontinent breakup

As heat builds up beneath a supercontinent, continental rifting begins. Basaltic lavas fill in the rift and eventually lead to seafloor spreading and the formation of a new ocean basin. This basalt province is where Africa is splitting apart and generating basalt lava.

the breakup of pangaea

At the end of the Paleozoic there was one continent and one ocean. When Pangaea began to break apart about 180 million years ago, the Panthalassa Ocean separated into the individual but interconnected oceans that we see today on Earth. The Atlantic Ocean basin formed as Pangaea split apart. The seafloor spreading that pushed Africa and South America apart is continuing to enlarge the Atlantic Ocean (Figure 1.1). As the continents moved apart there was an intense period of plate tectonic activity. Seafloor spreading was so vig- orous that the mid-ocean ridge buoyed upwards and displaced so much water that there was a marine transgression. Later in the Mesozoic those seas regressed and then transgressed again.

growth of continents

The moving continents collided with island arcs and microcontinents so that mountain ranges accreted onto the continents edges. The subduction of the oceanic Farallon plate beneath western North America during the late In the Afar Region of Ethiopia, Africa is splitting apart. Three plates are pulling away from a central point. Jurassic and early Cretaceous produced igneous intrusions and other structures. The intrusions have since been uplifted so that they are exposed in the Sierra Nevada Mountains (Figure 1.2). The snow-covered Sierra Nevada is seen striking SE to NW across the eastern third of the image. The mountain range is a line of uplifted batholiths from Mesozoic subduction. Click image to the left or use the URL below. URL:

textbook_image

textbook_image

instructional diagrams

No diagram descriptions associated with this lesson

questions

heat builds up beneath a supercontinent, causing which to happen?

a) continent collision

-->  b) continental rifting

c) continents to stay in place

d) none of the above

shear wave velocity beneath new mexico indicates hot material, which could mean ____ at the rio grande rift.

a) north america will rift apart

b) new seafloor could form

c) a large basalt province could erupt

-->  d) all of the above

in the afar region of ethiopia, africa is splitting apart, where __ plates are pulling away from each other.

a) one

b) two

-->  c) three

d) four

as pangaea broke apart,

-->  a) seafloor spreading was so vigorous that there was a marine transgression.

b) the panthalassa ocean split into several separate and unconnected oceans.

c) the pacific ocean basin formed between africa and south america.

d) all of the above.

if vigorous seafloor spreading can cause a marine transgression then calmer seafloor spreading can cause

-->  a) a marine regression.

b) mountain ranges to uplift.

c) sea levels rise and fall.

d) all of these.

the subduction of the farallon plate beneath western north america produced the ____ that we see today.

a) appalachian mountains

-->  b) sierra nevada mountains

c) himalaya mountains

d) andes mountains

the subduction of the farallon plate produced massive basalt flows that we still see today.

a) true

-->  b) false

pangaea split apart when

a) too much heat built up beneath the continent.

b) continental rifting began to think the continental crust.

c) seafloor spreading separated the continents.

-->  d) all of these.

pangaea began to break up about

a) 18 million years ago

b) 80 million years ago

-->  c) 180 million years ago

d) 800 million years ago

the sierra nevada mountains are a line of uplifted batholiths from mesozoic subduction.

-->  a) true

b) false

diagram questions

No diagram questions associated with this lesson