古地理学报 ›› 2014, Vol. 16 ›› Issue (1): 77-88. doi: 10.7605/gdlxb.2014.01.077

• 地球化学与沉积环境 • 上一篇    下一篇

广西东南部钦防海槽晚古生代硅质岩地球化学特征及其地质意义*

胡丽沙1, 徐亚军1, 杜远生1, 黄宏伟2, 徐旺春1, 邝国敦2   

  1. 1 中国地质大学(武汉)生物地质与环境地质国家重点实验室,湖北武汉 430074
       2 广西地质勘察总院,广西南宁 530023
  • 收稿日期:2013-05-10 修回日期:2013-08-05 出版日期:2014-02-01 发布日期:2014-02-01
  • 通讯作者: 杜远生,男,1958年生,中国地质大学(武汉)教授、博士生导师,主要从事造山带沉积地质学研究。E-mail: duyuansheng126@126.com。
  • 作者简介:胡丽沙,女,1987年生,中国地质大学(武汉)博士研究生,主要从事沉积地球化学、沉积盆地及造山带研究。E-mail:hulisha2129@163.com。
  • 基金资助:
    国家自然科学基金项目(编号:41272120)和中央高校基本科研业务费专项资金资助项目共同资助。

Geochemical characteristics and its geological significance of the Late Paleozoic siliceous rocks in Qinfang Trough,southeastern Guangxi

Hu Lisha1, Xu Yajun1, Du Yuansheng1, Huang Hongwei2, Xu Wangchun1, Kuang Guodun2   

  1. 1 State Key Laboratory of Biogeology and Environmental Geology,China University of Geosciences(Wuhan),Wuhan 430074,Hubei
    2 General Academy of Geological Survey of Guangxi,Nanning 530023,Guangxi
  • Received:2013-05-10 Revised:2013-08-05 Online:2014-02-01 Published:2014-02-01
  • Contact: Du Yuansheng,born in 1958,is a professor and Ph.D. supervisor of China University of Geosciences(Wuhan),and is mainly engaged in sedimentary geology of orogenic belt.E-mail: duyuansheng126@126.com.
  • About author:Hu Lisha,born in 1987,is a Ph.D. candidate of China University of Geosciences(Wuhan),and is mainly engaged in sedimentary geochemistry,basin and orogenic belts analyses.E-mail: hulisha2129@163.com.

摘要: 广西东南部钦防海槽地区晚古生代硅质岩十分发育。对硅质岩主量元素、微量元素及稀土元素的分析结果表明:该区晚古生代硅质岩含有较高的SiO2,硅化程度较高;除上泥盆统弗拉斯阶及下石炭统硅质岩具有较低的Al/(Al+Fe+Mn)值(0.14~0.24;0.07~0.81)及较高的U/Th值(0.34~5.09;0.16~10.1)外,其他层位硅质岩具有较高的Al/(Al+Fe+Mn)值(0.4~0.95)及较低的U/Th值(0.1~2.1);上泥盆统硅质岩稀土元素比值Ce/Ce*、LaN/YbN及LaN/CeN值分别为0.78~1.08、0.4~1.52和0.88~1.35,而下石炭统硅质岩具有较低的Ce/Ce*值(0.55~0.91)、LaN/YbN值(0.12~1.8)及较高的 LaN/CeN值(1.12~1.79),中下二叠统硅质岩Ce/Ce*、LaN/YbN及LaN/CeN值分别为1.01~1.62、0.72~2.71和0.62~1.9。钦防海槽晚古生代硅质岩地球化学特征表明:晚泥盆世钦防海槽发生扩张,热液活动比较强烈,处于大陆边缘海环境;早石炭世钦防海槽再次发生扩张,热液活动强烈,硅质岩形成于远离陆源的深海海盆环境;早中二叠世,钦防海槽逐渐收缩,海水变浅。钦防海槽晚古生代并没有出现真正的洋壳,可能属于晚古生代古特提斯分支洋盆的一个坳拉槽盆地。

关键词: 钦防海槽, 硅质岩, 地球化学, 晚古生代

Abstract: The Late Paleozoic siliceous rocks in the Qingfang Trough were well developed.Based on the analyses of major elements,trace elements and rare earth elements,it was concluded that the Late Paleozoic siliceous rocks contain high content of SiO2 and high silicification degree;the Upper Devonian Frasnian and Lower Carboniferous siliceous rocks have lower Al/(Al+Fe+Mn)value (0.14-0.24;0.07~0.81)and higher U/Th value(0.34~5.09;0.16~10.1),whereas the Famennian and Lower-Middle Permian siliceous rocks have higher Al/(Al+Fe+Mn)value(0.4~0.95) and lower U/Th value(0.1~2.1),illustrating that the Frasnian and the Lower Carboniferous siliceous rocks were influenced by the hydrothermal process but the Famennian and the Lower-Middle Permian siliceous rocks were biogenic origin;Ce/Ce*, LaN/YbN,and LaN/CeN values for the Upper Devonian siliceous rocks are 0.78~1.08,0.4~1.52 and 0.88~1.35,whereas these values for the Lower Carboniferous siliceous rocks are 0.55~0.91,0.12~1.8 and 1.12~1.79,and the Lower-Middle Permian siliceous rocks have Ce/Ce*,LaN/YbN,and LaN/CeN values of 1.01~1.62,0.72~2.71 and 0.62~1.9;Geochemical characteristics of the Late Paleozoic siliceous rocks in the Qinfang Trough indicated that the Qinfang Trough expanded within an epicontinental sea environment during the Late Devonian with hydrothermal activity,then expanded again in the Early Carboniferous with siliceous rocks formed in deep sea basin environment,and in the Early Permian the Qinfang Trough shrinked gradually to a continental margin basin. In a conclusion,the Qinfang Trough is more like a sea basin and may be belong to the Aulacogen of Paleo-Tethys Ocean in Late Paleozoic,and an ocean crust had never been formed.

Key words: Qinfang Trough, siliceous rocks, geochemistry, Late Paleozoic

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