本文研究了六盘山西麓新近系黄土沉积的分布,并在山前冲积高地上考察了近连续黄土剖面(南坪剖面)。磁化地层学与QA-Ⅰ中新世黄土层序的对比研究表明,该56 m剖面覆盖~8.1 ~ 6.2 Ma区间。该剖面的下界年龄与前人报道的~9 ~ 8(~8 ~ 4.8 ~8) Ma的近连续黄土和(~8.1 ~ 2.58 ~8)Ma的潮那红粘土,表明六盘山在晚中新世(~9 ~8)抬升,基本由~8 ~8 Ma形成。证明从那时起就没有激烈的造山活动。
此外,根据庄浪岩心和QA-Ⅰ剖面资料,研究组推断六盘山相当一部分在晚渐新世-中新世早期隆升,而在~22 ~ 9Ma期间没有剧烈隆升。
据悉,六盘山位于青藏高原东北部与鄂尔多斯地块的交界处,是中国西部重要的山脉之一。六盘山的隆升历史仍有争议。黄土对侵蚀敏感,黄土的形成和保存需要相对平坦的高原和相对稳定的构造环境,因此黄土沉积是区域构造和地貌变化的良好示踪剂。
附:英文原文
Title: Late Cenozoic uplift of the Liupan Mountains: Evidence from the Neogene loess deposits
Author: Zhilin HE, Yansong QIAO, Zhengtang GUO, Chaoqin CHEN, Long CHEN, Yang FU, Ye YANG, Yanxia LIANG, Xinru LIN, Guoqiao XIAO, Tao ZHAN
Issue&Volume: 2024/04/19
Abstract: The Liupan Mountains, one of the important mountain ranges in western China, are located on the boundary between the northeastern Tibetan Plateau and the Ordos Block. The uplift history of the Liupan Mountains remains controversial. Loess deposits are good tracers of regional tectonic and geomorphic changes, because loess is sensitive to erosion and the formation and preservation of loess requires relatively flat highlands and relatively stable tectonic environments. We investigated the distribution of Neogene loess deposits on the western piedmont of the Liupan Mountains and examined a near-continuous loess section (Nanping section) on the piedmont alluvial highlands. Correlation of magnetic susceptibility stratigraphy with the QA-Ⅰ Miocene loess sequence dates this 56-m section covering the interval from ~8.1 to 6.2Ma. The lower boundary age of this section, together with previously reported Zhuanglang red clay (sand-gravel layers with intercalated loess during ~9–8Ma and near-continuous loess during ~8–4.8Ma) and Chaona red clay (~8.1–2.58Ma), indicates that the Liupan Mountains were uplifted in the late Miocene (~9–8Ma) and basically formed by ~8Ma, attesting to no intense mountain building since that time. In addition, based on the information from the Zhuanglang core and the QA-Ⅰ section, we infer that sizable parts of the Liupan Mountains were uplifted during the late Oligocene–early Miocene and did not experience intense uplift during ~22–9Ma.
DOI: 10.1007/s11430-023-1319-2
Source: https://www.sciengine.com/10.1007/s11430-023-1319-2
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