Page 393 - Global Tectonics

PRECAMBRIAN TECTONICS AND THE SUPERCONTINENT CYCLE 375

South China Siberia

?
Tarim
South Africa Greenland
? Baltica
Australia
India North
America
? East Scotland
Antarctica West
South Africa
North China America
M
Possible pre-Rodinia basement covered
by Phanerozoic cover or ice
Exposed pre-Rodinia basement
2.1–1.8 Ga orogens
1.8–1.3 Ga orogens

Fig. 11.22 Reconstruction of the postulated Early–Middle Proterozoic supercontinent Columbia (after Zhao et al.,
2002, with permission from Elsevier). M, Madagascar. Early Proterozoic orogens (2.1–1.8 Ga) are identified in Fig. 11.12.

(a) ~545 Ma (b) ~465 Ma
30 N
TxP LAURENTIA Pacific LAURENTINA
EAST Ocean
Extensional margin
GONDWANA
0 0 TxP
K
F Western
30 CT Iapetus
RP S
E SIBERIA
30 S
60 C Eastern
SF Iapetus
AM GONDWANA
WEST B
GONDWANA Avalonia
WA
60 S
F Tornquist BALTICA
Sea
Avalonia Cadomian arc

Fig. 11.23 Postulated reconstructions of (a) Pannotia at ∼545 Ma and (b) the rifting of Laurentia and Gondwana at
∼465 Ma emphasizing the paleogeography of Laurentia relative to Gondwana (after Dalziel, 1997, with permission

from the Geological Society of America). Crosses with 95% confidence circles shown in (a) with a dashed line and a
dashed-dotted line indicate paleomagnetic poles for Laurentia and Gondwana, respectively. Horizontal lines in (a)
denote limit of the Mozambique orogenic belt; thick solid black line marks the location of a Laurentia–Gondwana rift.

In (b) paleomagnetic poles are for Laurentia + Baltica + Siberia + Avalonia (cross with dashed confidence circle) and

Gondwana (cross with dashed-dotted confidence circle). Cuyania (CT) has accreted onto the Gondwana margin.
Abbreviations: C, Congo; K, Kalahari; WA, West Africa; AM, Amazonia; RP, Río de la Plata; SF, São Francisco; S, Siberia; B,
Baltica; TxP, the hypothetical Texas Plateau; F, Famatina arc; E, Exploits arc.