中国科学院南京地质古生物研究所机构知识库

The northern slope of the Eastern Qinling Ranges is situated in a transitional region between the Qinling Fold Belt and the North China Platform. The Neoproterozoic Dongjia Formation of the northern slope of the East Qinling Ranges sits immediately beneath the glaciogenic Luoquan Formation. Abundant and moderately diverse organic-walled microfossils have been obtained by palynological preparation from grey-green sandy shale and grey carbonaceous shale with intercalated sandstone in the lower part of the Dongjia Formation. By considering known stratigraphic distributions of acritarchs, and abundant radial fibrous fabrics in microdigitate stromatolites and,a narrow range of delta(13)C values (ca. 0 +/- 1 parts per thousand vs. PDB) from the underlying carbonate successions, the age of the Dongjia Formation is estimated to be early Neoproterozoic. In addition, many specimens of small Micrhystridium-like spinose acritarchs have been found in the glaciogenic Luoquan Formation. This supports the presence of a 'Luoquan Glacial Period' after the Varangian glaciation. Nine previously described acritarch species have been identified, and one new combined species, three uncertain species, one undetermined form and fragment of an algal colony are described. (C) 1999 Published by Elsevier Science B.V. All rights reserved.