...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of Asian earth sciences >A major change in precipitation gradient on the Chinese Loess Plateau at the Pliocene-Quaternary boundary
【24h】

A major change in precipitation gradient on the Chinese Loess Plateau at the Pliocene-Quaternary boundary

机译：黄土高原上新世-第四纪边界处降水梯度的主要变化

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Spatiotemporal variations in East Asian Monsoon (EAM) precipitation during the Quaternary have been intensively studied. However, spatial variations in pre-Quaternary EAM precipitation remain largely uninvestigated, preventing a clear understanding of monsoon dynamics during a warmer climatic period. Here we compare the spatial differences in heavy mineral assemblages between Quaternary loess and pre-Quaternary Red Clay on the Chinese Loess Plateau (CLP) to analyze spatial patterns in weathering. Prior studies have revealed that unstable hornblende is the dominant (similar to 50%) heavy mineral in Chinese loess deposited over the past 500 ka, whereas hornblende content decreases to 10% in strata older than similar to 1 Ma in the central CLP because of diagenesis. In the present study we found that hornblende is the dominant heavy mineral in 2-2.7 Ma loess on the northeastern CLP (at Jiaxian), which today receives little precipitation. Conversely, hornblende content in the upper Miocene-Pliocene Red Clay at Jiaxian is 10%, as in the central CLP. The early Quaternary abundance of hornblende at Jiaxian indicates that the current northwestward-decreasing precipitation pattern and consequent dry climate at Jiaxian must have been initiated since 2.7 Ma, preventing hornblende dissolution to amounts 10% as observed in the central CLP. By contrast, the 7 Ma and 3 Ma Jiaxian Red Clay hornblende content is significantly less than that of the Xifeng samples, despite the fact that today Xifeng receives more precipitation than Jiaxian, with expected enhanced hornblende weathering. This suggests that the northeastern CLP received more precipitation during the Late Miocene-Pliocene than at Xifeng, indicating that the precipitation gradient on the CLP was more east west during the Late Miocene-Pliocene rather than northwest southeast as it was in the Quaternary. A comparison of magnetic susceptibility records for these sections confirms this inference. We attribute this major change in climatic patterns at 2.7 Ma to decreased northward moisture transportation associated with Northern Hemisphere glaciation and cooling in the Quaternary. This study therefore demonstrates the potential usefulness of employing heavy mineral analysis in both paleoclimatic and paleooceanographic reconstructions.
机译：对第四纪东亚季风（EAM）降水的时空变化进行了深入研究。然而，第四纪EAM前期降水的空间变化仍未得到充分研究，这妨碍了人们在更暖的气候时期对季风动力学的清晰理解。在这里，我们比较了中国黄土高原（CLP）第四纪黄土和第四纪前红粘土之间重矿物组合的空间差异，以分析风化的空间格局。先前的研究表明，不稳定的角闪石是过去500 ka沉积的中国黄土中占主导地位的（约占50％）重矿物，而中部CLP年龄大于1 Ma的地层中，角闪石含量降低至<10％。成岩作用。在本研究中，我们发现角闪石是东北CLP（位于嘉县）的2-2.7 Ma黄土中的主要重矿物，今天很少降雨。相反，与中部CLP一样，Jia县中新世-上新世红粘土中的角闪石含量<10％。嘉县角闪石的第四纪早期丰度表明，自2.7 Ma以来，贾县当前的西北递减降水模式和随之而来的干旱气候必定已经开始，从而防止了角闪石的溶解量<10％（在中电中心观察到）。相比之下，尽管今天的西丰县降水量多于嘉县，但预计角麻风化作用增强，尽管如此，7 Ma和3 Ma的家县红粘土角闪石含量明显低于西峰样品。这表明东北中电在中新世-上新世末期比西峰地区接收到更多的降水，这表明中电在中新世-上新世末期的降水梯度更向西，而不是第四纪的西南。这些部分的磁化率记录的比较证实了这一推论。我们将这种气候模式在2.7 Ma处的主要变化归因于与北半球冰期和第四纪的降温有关的向北的水分输送减少。因此，这项研究表明在古气候和古海洋重建中采用重矿物分析的潜在有用性。

著录项

  • 来源
    《Journal of Asian earth sciences》 |2018年第15期|134-138|共5页
  • 作者

    Peng Wenbin; Nie Junsheng; Wang Zhao; Qiang Xiaoke; Garzanti Eduardo; Pfaff Katharina; Song Yougui; Stevens Thomas;

  • 作者单位

    Lanzhou Univ, Coll Earth & Environm Sci, Minist Educ, Key Lab Western Chinas Environm Syst, Lanzhou 730000, Gansu, Peoples R China;

    Lanzhou Univ, Coll Earth & Environm Sci, Minist Educ, Key Lab Western Chinas Environm Syst, Lanzhou 730000, Gansu, Peoples R China;

    Lanzhou Univ, Coll Earth & Environm Sci, Minist Educ, Key Lab Western Chinas Environm Syst, Lanzhou 730000, Gansu, Peoples R China;

    Chinese Acad Sci, Inst Earth Environm, SKLLQG, Xian 710075, Shaanxi, Peoples R China;

    Univ Milano Bicocca, Dept Earth & Environm Sci, Piazza Sci 4, I-20126 Milan, Italy;

    Colorado Sch Mines, Dept Geol & Geol Engn, 1516 Illinois St, Golden, CO 80401 USA;

    Chinese Acad Sci, Inst Earth Environm, SKLLQG, Xian 710075, Shaanxi, Peoples R China;

    Uppsala Univ, Dept Earth Sci, Villavagan 16, S-75123 Uppsala, Sweden;

  • 收录信息
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    Heavy mineral; QEMSCAN; Loess; Red clay; Precipitation; Quaternary; Pliocene; Hornblende weathering;

    机译：重矿物;QEMSCAN;黄土;红土;降水;第四纪;上新世;洪布伦德风化;

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号