Sedimentary records of the Yangtze Block (South China) and their correlation with equivalent Neoproterozoic sequences on adjacent continents
- 作者：Wei Wang ; Mei-Fu Zhou ; mfzhou@hkucc.hku.hk
- 关键词：Geochemistry ; U&ndash ; Pb&ndash ; Hf isotopes ; Detrital zircons ; Neoproterozoic ; Yangtze Block ; Rodinia
- 刊名：Sedimentary Geology
- 出版年：2012
- 期刊代码：81_00370738
- 类别：ear
- 出版时间：15 July, 2012
- 卷：265-266
- 期：Complete
- 页码：126-142
- 文件大小：2988 K
摘要
The Neoproterozoic Danzhou Group, composed of siliciclastic sedimentary rocks interbedded with minor carbonate and volcanic rocks in the southeastern Yangtze Block, South China, is thought to be related to the breakup of Rodinia. Detrital zircon ages constrain the deposition of the Danzhou Group at ~ 770 Ma and ~ 730 Ma. The Danzhou Group contains dominant Neoproterozoic detrital zircon grains (~ 740-900 Ma) with two major age groups at ~ 740-790 Ma and ~ 810-830 Ma, suggesting the detritus was largely sourced from the widely distributed Neoproterozoic igneous plutons within the Yangtze Block. The sedimentary rocks from the lower Danzhou Group, including sandstones, siltstone and pelitic rocks, have UCC-like chemical signatures, representing mixed products of primary sources. The upper Danzhou Group received more recycled materials because the rocks have relatively higher Zr/Sc ratios, Hf contents and a greater influx of Pre-Neoproterozoic zircons. All of the rocks have high La/Sc, low Sc/Th and Co/Th ratios, consistent with sources dominantly composed of granitic to dioritic end-members from the western and northwestern Yangtze Block. Chemical compositions do not support significant contributions of mafic components. Most Neoproterozoic zircons have positive 蔚Hf(t) (0-17) indicative of sediments derived mainly from the western and northwestern Yangtze Block. The uni-modal Neoproterozoic zircons and felsic igneous source rocks for the Danzhou Group suggest that the Yangtze Block was an independent continent in the peripheral part of Rodinia.