Eolian grain-size signature of the Sikouzi lacustrine sediments (Chinese Loess Plateau): Implications for Neogene evolution of the East Asian winter monsoonстатья из журнала
Аннотация: Research Article| May 01, 2010 Eolian grain-size signature of the Sikouzi lacustrine sediments (Chinese Loess Plateau): Implications for Neogene evolution of the East Asian winter monsoon Hanchao Jiang; Hanchao Jiang † 1State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, P.O. Box 9803, Beijing 100029, China †E-mail: hcjiang@ies.ac.cn or hanchaojiang@hotmail.com Search for other works by this author on: GSW Google Scholar Zhongli Ding Zhongli Ding 2Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China Search for other works by this author on: GSW Google Scholar Author and Article Information Hanchao Jiang † 1State Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, P.O. Box 9803, Beijing 100029, China Zhongli Ding 2Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China †E-mail: hcjiang@ies.ac.cn or hanchaojiang@hotmail.com Publisher: Geological Society of America Received: 21 Nov 2008 Revision Received: 19 Apr 2009 Accepted: 23 Apr 2009 First Online: 08 Mar 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 © 2010 Geological Society of America GSA Bulletin (2010) 122 (5-6): 843–854. https://doi.org/10.1130/B26583.1 Article history Received: 21 Nov 2008 Revision Received: 19 Apr 2009 Accepted: 23 Apr 2009 First Online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Hanchao Jiang, Zhongli Ding; Eolian grain-size signature of the Sikouzi lacustrine sediments (Chinese Loess Plateau): Implications for Neogene evolution of the East Asian winter monsoon. GSA Bulletin 2010;; 122 (5-6): 843–854. doi: https://doi.org/10.1130/B26583.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract In order to explore the Neogene evolution of East Asian winter monsoon circulation, grain-size analysis was conducted on the Neogene Sikouzi section, Guyuan, Ningxia, China, a relatively monsoon-sensitive region. The results show that most of the particles are fine, the sand-bearing samples (median grain size [Md] >63 μm) are less than 6.4%, and that all the grain-size distribution curves of representative samples have a similar pattern to those of eolian dust sediments on the Chinese Loess Plateau. Rare earth element (REE) patterns of eight samples from the Sikouzi section are all characterized by light (L) REE enrichments, relatively flat heavy (H) REE patterns, and slight negative Eu anomalies, similar to those of loess and the average upper continental crust. These lines of evidence point to a windblown origin of the Sikouzi fine sediments. Based on previous studies, the 10–70 μm fraction of the Sikouzi sediments is mainly transported by the East Asian winter monsoon, and an increase in content of the 10–70 μm fraction reflects strengthening of the winter monsoon. In contrast, sand grains in samples of Md >63 μm are probably brought into the study area by rivers and streams linked with precipitation enhancement. According to stratigraphic variations in content of various fractions of the Sikouzi grain-size record, the Neogene evolution of the East Asian monsoon circulation can be divided into three stages. During the period 20.1–12.0 Ma, the 10–70 μm fraction holds the lowest values, whereas sand content usually shows high percentages, denoting a weak winter monsoon and a strong summer monsoon. After 12.0 Ma, the 10–70 μm fraction increased substantially and remained at high values, while sand content showed a marked decline, indicating that the winter monsoon strengthened dramatically and the summer monsoon declined significantly. From 4.3 to 0.07 Ma, the winter monsoon strengthened further, as evidenced by the gradual increase in content of the 10–70 μm fraction. This inference agrees well with the timing of glaciation development in the Northern Hemisphere. During the early to middle Miocene, the high values of both Md and sand content are mainly distribute in five intervals, 19.8–18.8 Ma, 18.0–17.5 Ma, 16.7–15.6 Ma, 14.3–13.7 Ma, and 13.0–12.0 Ma, corresponding to five periods of intense precipitation. The interval from 16.7 to 15.6 Ma is well correlated with the middle Miocene climatic optimum determined by the well-known Miocene Shanwang biota from eastern China. As for the other four periods, it is speculated that episodic growth of the East Antarctic Ice Sheet possibly shifted atmospheric fronts such as the Intertropical Convergence Zone (ITCZ) and thus carried water vapor further northward, leading to increases in regional precipitation on the northern midlatitude continent, including North China. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
Год издания: 2009
Авторы: Hanchao Jiang, Z. L. Ding
Издательство: Geological Society of America
Источник: Geological Society of America Bulletin
Ключевые слова: Geology and Paleoclimatology Research, Geological and Geochemical Analysis, earthquake and tectonic studies
Открытый доступ: closed
Том: 122
Выпуск: 5-6
Страницы: 843–854