NEOPROTEROZOIC RECONSTRUCTIONS

The late Neoproterozoic (Ediacaran) continents were formed by the break-up of Rodinia, a late Precambrian ‘Pangea' that existed at about 750 Ma during the mid-Neoproterozoic (Cryogenian). The Rodinian fragments aggregated some time in the latest Neoproterozoic to form a possible, short-lived, latest Precambrian 'Pangea', named Pannotia, meaning all the southern continents (Powell 1995). The Rodinia to Pannotia transition spans the time of the ‘snowball Earth', when most of the continents were in high latitudes grouped around the South pole. Pannotia is the reassembly in which Gondwana itself came into being. Pannotia in turn broke up in latest Precambrian time as a result of the opening of the Iapetus Ocean. Most of the Pannotian fragments eventually came together as Wegener's classic Pangea of Permo-Triassic age.

Most mid- to late Neoproterozoic reconstructions agree in placing western South America against some part of eastern Laurentia, but the details vary. However, the proposed positions and orientations of Australia, East Antarctica and Baltica show much larger variations cf. Moores (1991), and Sears and Price (2000). This paper examines the paleomagnetic and tectonic implications of these models from a Phanerozoic viewpoint: i.e. it assumes a geocentric axisymmetric dipole field, characteristic indicators of continental margins, and no snowball Earth.

Moores, E. M., 1991, Southwest U.S.-East Antarctic (SWEAT) connection: A hypothesis: Geology, v. 19, p. 425-428. Powell, C. M., Li, Z. X., McElhinny, M. W., Meert, J. G., and Park, J. K., 1993, Paleomagnetic constraints on timing of the Neoproterozoic breakup of Rodinia and the Cambrian formation of Gondwana: Geology, v. 21, p. 889-892. Sears, J. W., and Price, R. A., 2000, New look at the Siberian connection: No SWEAT: Geology, v. 28, p. 423-426.