柴西红沟子地区晚新生代沉积特征及其对阿尔金山隆升的约束  

Late Cenozoic sedimentation characters of Honggouzi area in the western Qaidam Basin and its constraints on the uplift of the Altyn Tagh

作　　者：张大文[1,2] 张涛[1] 张伟林[1,3] 宋春晖[4] 颜茂都[1,3] 

机构地区：[1]中国科学院青藏高原研究所,大陆碰撞与高原隆升重点实验室,北京100101 [2]中国科学院大学,北京100049 [3]中国科学院青藏高原地球科学卓越创新中心,北京100101 [4]兰州大学地质科学与矿产资源学院,甘肃省西部矿产资源重点实验室,兰州730000

出　　处：《第四纪研究》2016年第4期832-846,共15页Quaternary Sciences

基　　金：国家自然科学基金项目（批准号：41272185、41321061和41301222）、国家重点基础研究发展规划项目（973项目）（批准号：2013CB956400）和中国科学院战略性先导科技专项项目（B类）（批准号：XDB03020000）共同资助致谢方小敏研究员和审稿专家对本文提出了宝贵意见,特别感谢第四纪研究编辑部杨美芳对本文提出的建议和意见,很好地提高了论文的质量.此外刘栋梁、孟庆泉、张玺正、李立立、王亚东、韩文霞、张志高、申苗苗、田茜等参加了野外采样及室内分析工作,在此一并表示感谢!

摘　　要：柴达木盆地是青藏高原东北缘的一个山间盆地，发育了巨厚的中-新生代地层，详细记录了盆地及周缘山地的构造活动历史。本文通过对柴达木盆地西北部厚约1040m并具有精确古地磁年代控制的红沟子剖面（包括下油砂山组、上油砂山组、狮子沟组和七个泉组）开展精细沉积学研究，包括岩性特征与沉积相、砾岩与砂岩含量变化、剖面沉积速率变化特征以及沉积区物源分析等，结果表明：1）红沟子剖面晚新生代沉积相经历了下油砂山组（〉17.0Ma） 的冲积扇或扇三角洲平原相到上油砂山组（17.0~9.8Ma）扇三角洲前缘-半深湖-扇三角洲前缘相，再到狮子沟组（9.8~5.0Ma）扇三角洲前缘相，最后转为七个泉组（〈5.0Ma）洪积扇相的较复杂的沉积演化过程；2）红沟子剖面大套砾岩主要集中于〉16.5Ma、9.8Ma以及〈5.0Ma，砂岩主要出现在9.8~5.0Ma；3）红沟子剖面沉积速率具有＂三低两高＂的变化特征，尤其在约9.8Ma沉积速率呈现陡增；4）红沟子剖面砾岩层砾石成分、古水流方向分析，并通过综合梳理对比前人在毗邻研究区不同剖面的沉积物物源研究结果，认为柴达木盆地西部中晚中新世（〉16.5~5.0Ma）沉积物可能主要来自北部的阿尔金山地区。基于上述认识，将红沟子剖面晚新生代沉积划分为5个演化阶段：1）〉16.5Ma 主要以粗颗粒砾岩为主的冲-洪积相沉积；2）16.5~9.8Ma 沉积环境主要为半深湖或前扇三角洲，以泥岩或泥灰岩等细颗粒为主，沉积速率较低；3）9.80~8.53Ma 沉积环境为扇三角洲前缘，岩性变粗且有大套砾岩堆积，沉积速率达到剖面最高值，并在9.8Ma存在不整合面；4）8.53~7.48Ma沉积环境基本与上一阶段类似，砾岩含量减少，砂岩沉积相对增加，沉积速率呈现低值特征；5）7.48~5.00Ma 主要是扇三角洲前缘沉积环境，砂岩含量较高，沉积速率较高�As an intermountain basin in the northeastern margin of the Tibetan Plateau, the Qaidam Basin developed thick Mesozoic-Cenozoic sediments that have recorded the tectonic evolution history of the basin and the peripheral mountains. This study presents a high-resolution sedimentary records from the Middle Miocene to the Early Pliocene 1040-thick sediments of the Honggouzi（HGZ）section（38°34＇N, 91°03＇E）, located in northwestern Qaidam Basin. The oldest strata developed in HGZ section are Jurassic clastic rocks, covered by the Xia Youshashan Formation, Shang Youshashan Formation, Shizigou Formation and Qigequan Formation in an upward sequence, which were well-dated to be 〉17.0Ma, ca.17.0~9.8Ma, ca.9.8~5.0Ma, and 〈5.0Ma by previous magnetostratigraphic work, respectively. High resolution sedimentary analyses including the lithology and sedimentary facies, the conglomerate and sandstone content changes, the sedimentation rate characteristics, and the provenance analysis of the studied area show that （1）the HGZ section experienced alluvial fan/fan delta plain environment of the Xia Youshashan Formation（〉17.0Ma） to the fan delta front/semi-deep lake/fan delta front environment of the Shang Youshashan Formation（17.0~9.8Ma）, and transferred from fan delta/shallow lake/fan delta of the Shizigou Formation （9.8~5.0Ma）to the diluvial fan of Qigequan Formation （16.5Ma, 9.8Ma and 〈5.0Ma, and the sandstone appeared at 9.8~5.0Ma; （3）the sedimentation rate of the HGZ section displays a characteristic of ＂three low stages, two high stages＂ pattern, especially, a sharp increase at 9.8Ma; （4）the conglomerate composition and paleocurrent analyses combined with previous provenance results from the different sections, close to HGZ section in the Altyn Tagh slope areas, indicate that the sediments of the western Qaidam Basin probably mainly derived from the Altyn Tagh area during 〉16.5~5.0Ma. Based on the above, the Late Cenozoic sedimentary evolution of the HGZ was divided into five st

关 键 词：柴达木盆地 红沟子地区 晚新生代沉积特征 阿尔金山隆升 

分 类 号：P534.621[天文地球—古生物学与地层学] P512.2[天文地球—地质学]