Page 396 - Global Tectonics

378 CHAPTER 11

Siberia

Baltica
30°N
North
China
South
Laurentia China
Paleotethys Equator
West Africa

Amazonia Gondwana Neotethys
30°S
Congo
India
Australia
Rio Plata
East 60°S
Antarctica
Kalahari
Subduction zones Seafloor spreading axis

Fig. 11.27 Reconstruction of Pangea at 250 Ma (after Torsvik, 2003, with permission from Science 300, 1379–81, with
permission from the AAAS). Major cratons are shown.

enies in North America, Africa, and southwest Europe. arctica began to separate by 150 Ma. Australia also
Collisions in Asia, including the suturing of Baltica and began to rift from Antarctic by 95 Ma with India separat-
Siberia to form the Ural Orogen at ∼280 Ma, resulted in ing from Antarctica at about the same time. These data
the final assembly of Pangea. The supercontinent at the indicate that the majority of Pangea break-up occurred

height of its extent at ∼250 Ma is shown in Fig. 11.27. during the interval 150–95 Ma. Small fragments of con-
Like its assembly, the fragmentation of Pangea was tinental crust such as Baja California and Arabia con-
heterogeneous. Break-up began in the mid-Jurassic with tinue to be rifted from the continental remnants of
the rifting of Lhasa and West Burma from Gondwana Pangea. As with the older supercontinents, the break-up
and the opening of the central Atlantic shortly after of Pangea was accompanied by the closure of oceans,
180 Ma (Lawver et al., 2003). Magnetic anomalies indi- such as Paleotethys and Neotethys (Fig. 11.27), and by
cate that by 135 Ma the southern Atlantic had started to collisions, including those that occur presently in south-
open. Rifting between North America and Europe ern Asia (Fig. 10.13), southern Europe, and Indonesia
began during the interval 140–120 Ma. Africa and Ant- (Fig. 10.28).