| 山东青岛地区灵山岛早白垩世碎屑岩锆石U-Pb-Hf同位素特征及其大地构造意义 |
| |
| 引用本文： | 孟元库,李日辉,徐扬,侯方辉.山东青岛地区灵山岛早白垩世碎屑岩锆石U-Pb-Hf同位素特征及其大地构造意义[J].地球科学,2018,43(9):3302-3323. |
| |
| 作者姓名： | 孟元库 李日辉 徐扬 侯方辉 |
| |
| 作者单位： | 1.中国地质调查局青岛海洋地质研究所, 山东青岛 266071 |
| |
| 基金项目： | 中国博士后面上项目2017M612220中国地质调查局工作项目1212011220113 |
| |
| 摘 要： | 苏鲁造山带东缘的灵山岛上发育有早白垩世碎屑岩，目前人们对其沉积的精确时代、成因机制和大地构造环境仍然存在着广泛的争议.利用LA-ICP-MS的方法对灵山岛上两套碎屑岩进行了锆石U-Pb测年，并对特征年龄谱中的代表性碎屑锆石进行了Lu-Hf同位素分析.结果表明:（1）碎屑锆石U-Pb测年结果显示，莱阳群法家茔组和青山群八亩地组下部的碎屑岩沉积时代分别为127±3 Ma和128±4 Ma，表明两套碎屑岩都是早白垩世中晚期的沉积产物；（2）灵山岛上两套碎屑岩具有完全相似的年龄谱以及锆石Hf同位素组成，表明发育软沉积变形的粉砂岩、泥岩和上覆的含砾粗砂岩具有相似的物源，并且源区组成较为单一，主要以亲华北的胶北地体为主，其次的物源区为苏鲁造山带；（3）胶莱盆地下白垩统莱阳群和灵山岛下白垩统莱阳群的碎屑锆石年龄谱对比表明，灵山岛上的莱阳群碎屑岩明显不同于胶莱盆地的莱阳群，暗示在早白垩世时，灵山岛上的两套碎屑岩可能受到区域断裂的控制，沉积于一个相对独立的盆地.综合结果表明，灵山岛地区莱阳群法家茔组可能沉积于断陷湖盆的萎缩期，早期的沉积以湖相为主，晚期主要以河流相为主，在此期间遭受到了强烈的火山地震作用，诱发了下部的湖相的砂泥岩发生大规模的滑塌和软沉积变形.
|
| 关 键 词： | 碎屑锆石U-Pb定年 早白垩世 沉积物源 苏鲁造山带 灵山岛 同位素 年代学 |
| 收稿时间： | 2018-01-08 |
U-Pb-Hf Isotopes and Tectonic Significance of Early Cretaceous Detrital Zircons on Lingshan Island,Qingdao of Shandong Province |
| |
| Abstract: | The Early Cretaceous clastic rocks were deposited on Lingshan island, the eastern segment of the Sulu orogenic belt. However, the accurate depositional age, formation mechanism and tectonic setting of the Early Cretaceous clastic rocks are still controversial. In this study, we conducted systematically detrital zircon LA-ICP-MS U-Pb dating for two sets of clastic rocks on Lingshan island, and carried out Lu-Hf isotopic analyses for the representative detrital zircons. The results show as follows:(1) The detrital zircon U-Pb analyses demonstrate that the Fajiaying Formation and the clastic rocks from the bottom of the Bamudi Formation were deposited in the mid-late periods of Early Cretaceous, showing the synchronous depositional ages within the uncertainties, 127±3 Ma and 128±4 Ma, respectively. (2) Moreover, two sets of clastic rocks have the same age spectra and similar Hf isotopic compositions, indicating that the sandstone or mudstone characterized by soft sedimentary deformations and pebbly cearse sandstone have the similar sedimentary provenance, which was single and mainly derived from the Jiaobei terrane akin to the North China craton attributes, and then from the Sulu orogenic belt. (3) In comparison with the Jiaolai basin, the detrital zircons of the Laiyang Group in Lingshan island show different age spectra. We argue that the sedimentary rocks from Lingshan island might be deposited in an individual basin controlled by the fault different from the Jiaolai basin during Early Cretaceous. Integrated with previous studies, the Fajiaying Formation of the Laiyang Group on Lingshan island was possibly formed at the end of evolution of a lacustrine faulted-basin, and subsequently deposited a set of fluvial sediments characterized by pebbly sandstones at the top of the lacustrine sediments. Later on, the no-diagenetic sediments suffered from the strong volcanic earthquake, resulting in the soft sedimentary deformations and slump structures. |
| |
| Keywords: | |
| 本文献已被 CNKI 等数据库收录！ |
| 点击此处可从《地球科学》浏览原始摘要信息 |
|
点击此处可从《地球科学》下载全文 |
|
