Late Oligocene-early Miocene evolution of the Lunpola Basin, central Tibetan Plateau, evidences from successive lacustrine records
Late Oligocene-early Miocene evolution of the Lunpola Basin, central Tibetan Plateau, evidences from successive lacustrine records
复制标题
青藏高原中部伦坡拉盆地晚渐新世—早中新世演化——连续湖泊记录的证据
DOI：
10.1016/j.gr.2017.04.023
复制
发表时间：
2017-08-01
影响因子：
6.1
通讯作者：
Wang, Meng
中科院分区：
文献类型：
--
作者：
Ma, Pengfei;Wang, Chengshan;Wang, Meng
青藏高原及其周围广泛存在的新生代沉积物被认为在解释印度-亚洲碰撞过程及其与全球和区域古气候的相互作用方面发挥了重要作用。然而，沉积序列的高分辨率时间框架以及对地质和气候事件的控制仍然缺乏。为了研究上述问题，我们对青藏高原中部伦坡拉盆地渐新统-中新统湖泊序列（丁清湖组）进行了研究。在这项工作中，利用伽马射线测井和花粉数据进行旋回地层分析，以建立范围从约 100 到 100 的高分辨率时间框架。剖面为 25.4 至 18.0 Ma。沿着这些断面，利用轨道信号计算沉积物堆积率，以监测湖盆的碎屑输入；总结了元素、孢粉学和同位素数据，以描述该排水系统的古气候和古海拔演化。将所有这些线索整合在一起，我们整理出一份包括湖盆、构造和古气候在内的事件的时间清单：区域隆升发生在23.7Ma；同时，发现了以沉积物积累速度加快为特征的明显湖盆转变；约0.2 Ma后的23.5 Ma，流域出现规模干旱，并维持至断面结束。研究结果表明，古气候对湖盆晚渐新世-早中新世演化没有产生决定性影响；相反，区域隆升及其相关的源区加速剥露导致了湖盆转变和古气候干旱。通过回顾青藏高原及其周边分布的渐新世-中新世沉积记录，我们认为伦坡拉盆地23.7 Ma地质事件很可能不是一个单一事件，而是高原剧烈构造转变的区域效应。 (C) 2017 年国际冈瓦纳研究协会。由 Elsevier B.V. 出版。保留所有权利。
Widespread Cenozoic sediments in and around the Tibetan Plateau (TP) are thought to have played an important role in explaining the process of the India-Asia collision as well as its interactions with global and regional paleoclimate. However, high-resolution temporal frameworks of sedimentary sequences and controls on geological and climatic events are still absent. To study the abovementioned issues, we investigate the Oligocene-Miocene lacustrine sequences (the Dingqinghu Formation) of the Lunpola Basin, central TP. In this work, cyclostratigraphic analyses are conducted with gamma ray log and pollen data to establish a high resolution temporal framework ranging from ca. 25.4 to 18.0 Ma for the sections. Along these sections, sediment accumulation rates are calculated with orbital signals to monitor clastic input of the lake basin; elemental, palynological, and isotopic data are summarized to depict the paleoclimate and paleoelevation evolution of this drainage system. Integrating all these clues together, we sort out a chronological list of events including lake basin, tectonics, and paleoclimate: regional uplift took place at 23.7 Ma; simultaneously, a distinct lake-basin transition characterized by accelerated sediment accumulation rate is recognized; about 0.2 Ma later at 23.5 Ma, catchment scale drought occurred and maintained to the end of the sections. Our results demonstrate that paleoclimate did not impose decisive influence on the late Oligocene-early Miocene evolution of the lake basin; instead, regional uplift and its associated accelerated exhumation of the source area resulted in the lake-basin transition and paleoclimatic drought. After reviewing the Oligocene-Miocene sedimentary records distributed in and around the TP, we argue that the 23.7 Ma geological event of the Lunpola Basin is probably not a single case but a regional effect of a dramatic tectonic transition of the plateau. (C) 2017 International Association for Gondwana Research. Published by Elsevier B.V. All rights reserved.