Page 92 - Handbook of Gold Exploration and Evaluation

Geology of gold ore deposits 73

· the southward movement of Gondwanaland, which carried it over the South
Pole and then northwards to where it would eventually form part of Pangaea
about 350 mya
· closure of the ocean between Gondwanaland and other continental fragments,
which commenced about 310 mya, and led to the westward movement of
China, and that of Siberia from low latitudes to high latitudes, (merging with
Kazakhstania to form the Ural Mountains).

The supercontinent Pangaea
The successive break-up of the supercontinents Rodinia and Pannotia and their
reassembly as Pangaea (250±300 mya) dominated Phanerozoic geological
history. Reassembly of the landmasses occurred with the formation of the super-
continent Pangaea (all lands) surrounded by a single large ocean Panthalassa (all
oceans) about 300±250 million years ago (Fig. 2.4). Two major rifts illustrated
schematically in Fig. 2.5 were developed during a period of extensive orogenic
activity about 200±180 million years ago (Hoffman, 1989). The Sea of Tethys
divided Pangaea into `Laurentia-Baltica-Siberia' in the northern hemisphere, and
`Gondwanaland' in the south (Hoffman, 1989; Moores, 1982).

Laurentia-Baltica-Siberia

The major northern continental mass, which evidently rotated in an anti-
clockwise direction as a single plate after an initial period of intense orogenic

2.4 The supercontinent Pangaea.