Map : Detail of Siberian Terrane
Earth History Maps of professor Jan Golonka
This was a quiet time without any major collisions, but of a continuing sea-level rise. The continents of Gondwana, Baltica, Laurentia and Siberia continued their existence. Siberia and Laurentia drifted northward coming close to the equator (Figs 2, 3).
Some of the late Vendian/ Early Cambrian events may have reached a conclusion at this time, like the Damara Orogeny (Miller, 1983; Henry at al., 1990; Tankard et al., 1995) in southern Africa or the orogenic events in the Ural, Timan-Pechora, Novaya Zemlya, and Pay- Khoy areas on the northeastern margin of Baltica. The collision of the Trans-Ural microcontinent with Baltica in the Ural area (Zonenshain et al., 1990) was perhaps related to adjustment of continents during the drifting stage. The subduction zone along the margin of Gondwana between Northwestern South America and the Chinese terranes, and the subduction zone located north of western Laurentia, Arctic plates and Siberia continued to develop.
Advanced seafloor spreading occurred in the Iapetus-Tornquist ocean between Laurentia and Baltica, and in the Phoibic Ocean between Laurentia and Gondwana (McKerrow et al., 1991; Torsvik et al.; 1996, Dalziel, 1997). Laurentia rapidly drifted northward and rotated counter-clockwise, reaching low latitudes. Seafloor spreading also occurred within the Pleionic Ocean between East Siberia and Baltica. Rifting events occurred along the Northern Urals and Pay Khoy belts on the eastern margin of Baltica (Nikishin et al., 1996), perhaps following the orogenic events mentioned above. The relationship between Laurentia and Siberia, including the mapped strike-slip, remains quite speculative (Fig.3). Extensive continental rifting occurred in Gondwana (e.g., East Arabian plate), East Siberia and Avalonia. In Laurentia intracontinental rifting affected the Wichita Mountains area in Oklahoma (Hamilton, 1989). Back-arc spreading in eastern Australia could have happened at this time (Powell et al., 1990, Veevers & Powell, 1990).
Sea Level and Climate
Sauk II was a time of continuous global sea level rise, related to advanced drifting of the continents and significant subsidence and submergence of most continental margins. Warm, humid climatic conditions, limited continental aridity, and no known continental glaciation exemplified the time of transition from icehouse to greenhouse conditions. The northward drift of Laurentia placed this continent in low latitudes. The global Ocean Anoxic Event (OAE), during the Middle and Late Cambrian, is related to climatic and sea-level conditions.
Carbonate deposition at that time was widespread, with carbonate platform occurrences distributed between 40oN and 60oS latitudes. Carbonate depositional systems, located along narrow continental margins or on isolated platforms typically consisted of oolitic grainstone-bearing, shallowing-upward depositional sequences that contain or are capped by peritidal dolomites.
Siberia was almost completely submerged (Fig. 3) and was characterized by shaly carbonate sediment accumulation which continued from the previous time slice (Puchkov, 1996). Carbonate and mixed carbonate/clastic facies were widespread in the northern part of North America and proto-Arctic area (Ronov et al., 1984). Carbonates also appeared on eastern North America margins, in connection with the Laurentia drift to the lower latitudes. large carbonate platform existed on the South China plate (Shouxin Yongyi, 1991) and was connected with the carbonate deposition area on the Arabia plate margin (Ronov et al., 1984). Mixed carbonate/clastic facies prevailed in South-East Asia (Brookfield, 1996). Carbonates are present within terrigenous complexes in the northern India-Himalayan area (Gupta & Brookfield, 1991). Carbonate/evaporite sediments were deposited on the Gondwanian margins in South America. Carbonate and mixed carbonate/clastic facies also occurred in Eastern Australia (Cook, 1990).