globalchange  > 过去全球变化的重建
DOI: 10.1016/j.palaeo.2016.10.004
论文题名:
A petrographic and geochemical study of carbonate and silica phases from the Ediacaran Doushantuo Formation in the Three Gorges area of South China: Implications for diagenetic conditions
作者: Zhao Y.-Y.; Jiang S.-Y.; Li D.; Yang J.-H.
刊名: Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN: 0031-0182
出版年: 2016
卷: 463
起始页码: 150
结束页码: 167
语种: 英语
英文关键词: Chert ; Diagenesis ; Nodules ; Oxygen isotope ; REEs ; Trace element
英文摘要: The carbonate of the Ediacaran Doushantuo Formation contains various silica phases in the Three Gorges area of South China. To better understand the diagenetic conditions under which these silica phases formed, we carried out a petrographic and geochemical study of the silica phases and the coadjacent carbonate phases at the Xiaofenghe section (XFH), in the Three Gorges area of South China. Five types of silica phases can be distinguished based on petrographic characteristics: S1 and S2 are composed of microcrystalline quartz, in chert nodules and disseminated in the host dolostone, respectively. S3 is composed of the megaquartz, while S4 and S5 are microcrystalline quartz and fibrous silica, respectively, both replacing calcite cement. Six distinct types of carbonate can be recognized, including the host matrix carbonate (C1), sparry calcite nodules (C2), calcite around chert nodules (C3), dispersed calcite cement within chert nodules (C4), fine micropeloidal calcite cements (C5) and calcite veins (C6). Sedimentary structures suggest that formation of the S1 through S5 silica phases and C2 through C5 carbonate phases occurred during early burial diagenesis, and therefore their formation recorded early diagenetic conditions. Assuming that Ediacaran surface seawater temperature ranged from 28 to 39 °C, surface seawater δ18O values can be calculated based on the oxygen isotopic composition of the host dolostone matrix (C1), which range from − 6 to 0‰, − 4 to 0‰, and − 2 to 0‰, for the D2, D3 and D4 subunits of the Doushantuo Formation, respectively. Based on the δ18O values of chert nodules and beds (mainly phase S1), diagenetic temperatures can be constrained to between 27 and 60 °C. Under such low diagenetic temperatures, the primary geochemical signatures of the host dolostone, such as REE + Y patterns, δ13CCarb and δ34SPy values, are likely to be preserved. Those silica phases without evidence of contamination of continental silicate detritus show characteristic REE + Y patterns, with minor light REE depletions, positive La, Eu and Gd anomalies, negative Ce anomalies and slightly super-chondritic Y/Ho ratios, implying that the source of silica may be derived from seawater. Negative Ce anomalies in the silica phases in D2 through D4 subunits indicate that the bottom seawater or early diagenetic porewater was oxic at the time of silica precipitation. © 2016 Elsevier B.V.
Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/68185
Appears in Collections:过去全球变化的重建

Files in This Item:

There are no files associated with this item.


作者单位: College of Marine Geosciences, Ocean University of China, Qingdao, China; Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Qingdao, China; CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Science, University of Science and Technology of China, Hefei, China; State Key Laboratory of Geological Processes and Mineral Resources, Faculty of Earth Resources, China University of Geosciences, Wuhan, China; State Key Laboratory for Mineral Deposits Research, Department of Earth Sciences, Nanjing University, Nanjing, China

Recommended Citation:
Zhao Y.-Y.,Jiang S.-Y.,Li D.,et al. A petrographic and geochemical study of carbonate and silica phases from the Ediacaran Doushantuo Formation in the Three Gorges area of South China: Implications for diagenetic conditions[J]. Palaeogeography, Palaeoclimatology, Palaeoecology,2016-01-01,463
Service
Recommend this item
Sava as my favorate item
Show this item's statistics
Export Endnote File
Google Scholar
Similar articles in Google Scholar
[Zhao Y.-Y.]'s Articles
[Jiang S.-Y.]'s Articles
[Li D.]'s Articles
百度学术
Similar articles in Baidu Scholar
[Zhao Y.-Y.]'s Articles
[Jiang S.-Y.]'s Articles
[Li D.]'s Articles
CSDL cross search
Similar articles in CSDL Cross Search
[Zhao Y.-Y.]‘s Articles
[Jiang S.-Y.]‘s Articles
[Li D.]‘s Articles
Related Copyright Policies
Null
收藏/分享
所有评论 (0)
暂无评论
 

Items in IR are protected by copyright, with all rights reserved, unless otherwise indicated.