Journal of the Geological Society, 1992

Climatically-related sedimentary facies and faunal distributions have been combined with palaeomagnetic data to make provisional reconstructions of the early Cambrian world. Laurentia, Baltica and Siberia appear to have formed a continental group which rifted apart from each other prior to 600 Ma. The consolidation of much of Gondwana probably occurred (in the Pan-African orogeny) well before the Cambrian, though the assembly of several east Asian terranes is still speculative. The archaeocyathan reefs of Siberia, southern Europe and Morocco, with their bigotinid trilobite fauna, suggest that these areas were adjacent to each other and at low latitudes. Avalonia had close faunal links with western Gondwana, but lacked bigotinids and archaeocyathans and may have been situated off west Africa and Florida. During the early Cambrian, there was a northward migration of Laurentia towards the Equator as its separation from Baltica and Siberia increased, and a southward movement of Gondwana.

2009

2009.04 The plate tectonic and palaeogeographic history of the late Proterozoic is a tale of two supercontinents: Rodinia and Pannotia. Rodinia formed during the Grenville Event (c. 1100 Ma) and remained intact until its collision with the Congo continent (800-750 Ma). This collision closed the southern part of the Mozambique Seaway, and triggered the break-up of Rodinia. The Panthalassic Ocean opened as the supercontinent of Rodinia split into a northern half (East Gondwana, Cathaysia and Cimmeria) and a southern half (Laurentia, Amazonia-NW Africa, Baltica, and Siberia). Over the next 150 Ma, North Rodinia rotated counter-clockwise over the North Pole, while South Rodinia rotated clockwise across the South Pole. In the latest Precambrian (650-550 Ma), the three Neoproterozoic continents--North Rodinia, South Rodinia and the Congo continents--collided during the Pan-Africa Event forming the second Neoproterozoic supercontinent, Pannotia (Greater Gondwanaland). Pan-African mountain building and the fall in sea level associated with the assembly of Pannotia may have triggered the extreme Ice House conditions that characterize the middle and late Neoproterozoic. Although the palaeogeographic maps presented here do not prohibit a Snowball Earth, the mapped extent of Neoproterozoic ice sheets favour a bipolar Ice House World with a broad expanse of ocean at the equator. Soon after it was assembled (c. 560 Ma), Pannotia broke apart into the four principal Palaeozoic continents: Laurentia (North America), Baltica (northern Europe), Siberia and Gondwana. The amalgamation and subsequent break-up of Pannotia may have triggered the "Cambrian Explosion". The first economically important accumulations of hydrocarbons are from Neoproterozoic sources. The two major source rocks of this age (Nepa of Siberia and Huqf of Oman) occur in association with massive Neoproterozoic evaporite deposits and in the warm equatorial-subtropical belt, within 30 degrees of the equator.

Developments in Precambrian Geology, 2009

Early Cambrian palaeogeography and the probable Iberia-Siberia connection, 2002

The end of the Proterozoic -beginning of the Cambrian is marked by some of the most dramatic events in the history of Earth. The fall of the Ediacaran biota, followed by the Cambrian Explosion of skeletonised bilaterians, a pronounced shift in oceanic and atmospheric chemistry and rapid climatic change from 'snowball earth' to 'greenhouse' conditions all happened within a rather geologically short period of time. These events took place against a background of the rearrangement of the prevailing supercontinent; some authors view this as a sequence of individual supercontinents such as Mesoproterozoic Midgardia, Neoproterozoic Rodinia and Early Cambrian Pannotia. Assembled in the Mesoproterozoic, this supercontinent appears to have existed through the Neoproterozoic into the Early Cambrian with periodic changes in configuration. The final rearrangement took place during the Precambrian -Cambrian transition with the Cadomian and related phases of the Pan-African orogeny. The distribution of Early Cambrian molluscs and other small shelly fossils (SSF) across all continents indicates a close geographic proximity of all major cratonic basins that is consistent with the continued existence of the supercontinent at that time. Subsequently, Rodinia experienced breakup that led to the amalgamation of Gondwana, separation of Laurentia, Baltica, Siberia and some small terranes and the emergence of oceanic basins between them. Spreading oceanic basins caused a gradual geographic isolation of the faunal assemblages that were united during the Vendian -Early Cambrian. D

Precambrian Research, 2006

International Geology Review, 2010

Earth and Planetary Science Letters, 2000

The Rodinia reconstruction of the Neoproterozoic Supercontinent has dominated discussion of the late Precambrian Earth for the past decade and originated from correlation of sedimentary successions between western North America and eastern Australia. Subsequent developments have sited other blocks according to a distribution of V1100 Ma orogenic belts with break-up involving a putative breakout of Laurentia and rapid reassembly of continent crust to produce Gondwana by early Phanerozoic times. The Rodinia reconstruction poses several serious difficulties, including: (a) absence of palaeomagnetic correlation after V730 Ma which requires early fragmentation of continental crust although geological evidence for this event is concentrated more than 150 Ma later near the Cambrian boundary, and (b) the familiar reconstruction of Gondwana is only achieved by exceptional continental motions largely unsupported by evidence for ocean consumption. Since the geological evidence used to derive Rodinia is non-unique, palaeomagnetic data must be used to evaluate its geometrical predictions. Data for the interval V1150^500 Ma are used here to test the Rodinia model and compare it with an alternative model yielding a symmetrical crescent-shaped analogue of Pangaea (Palaeopangaea). Rodinia critically fails the test by requiring Antarctica to occupy the location of a quasi-integral Africa, whilst Australia and South America were much closer to their Gondwana configurations around Africa than implied by Rodinia. Palaeopangaea appears to satisfy palaeomagnetic constraints whilst surmounting geological difficulties posed by Rodinia. The relative motions needed to produce Gondwana are then relatively small, achieved largely by sinistral transpression, and consistent with features of Pan-African orogenesis; continental dispersal did not occur until the Neoproterozoic^Cambrian boundary. Analogies between Palaeopangaea and (Neo)pangaea imply that supercontinents are not chaotic agglomerations of continental crust but form by episodic coupling of upper and lower mantle convection leading to conformity with the geoid. ß

Middle Paleozoic has two periods: Silurian which lasts about 28Ma (444MaBP-416MaBP) and the Devonian which lasts about 57Ma (416MaBP-359MaBP). Silurian is marked by mass extinction of about 60% of marine creatures in the end of the Ordovician. Paleomagnetic studies outline the following paleotectonic picture of the Middle Paleozoic: Gondwana performed complex turn around the South Pole (Fig.20.1).