CAJ | 학술논문

运用碎屑锆石LA-ICP-MS U-Pb年代学分析方法，探讨分析了鄂尔多斯地块西南缘奥陶系平凉组沉积期的物源环境。结果表明：①平凉组凝灰质砂岩中的碎屑锆石U-Pb年龄大致包含3组：第一组为早古生代的407～477Ma，峰值为454Ma，占总体的72.5％；第二组为中—新元古代的588～1548Ma，峰值为962Ma，占总体的22.5％；第三组为古元古代的1612～2496Ma，占总体的5％。②集中在407～477Ma年龄组分指示其物源主要来自于祁连—北秦岭岛弧杂岩带，588～1548Ma和1612～2496Ma的年龄组分反映的物源主要来自于北秦岭造山带，祁连造山带和华北板块基底。③锆石年龄谱综合分析，平凉组碎屑沉积物质来源复杂，具有明显的多源性，指示晚奥陶世平凉期的沉积环境应属于祁连—北秦岭岛弧杂岩带与鄂尔多斯地块西南缘之间的局限残留边缘海盆地。
운용쇄설고석LA-ICP-MS U-Pb년대학분석방법，탐토분석료악이다사지괴서남연오도계평량조침적기적물원배경。결과표명：①평량조응회질사암중적쇄설고석U-Pb년령대치포함3조：제일조위조고생대적407～477Ma，봉치위454Ma，점총체적72.5％；제이조위중—신원고대적588～1548Ma，봉치위962Ma，점총체적22.5％；제삼조위고원고대적1612～2496Ma，점총체적5％。②집중재407～477Ma년령조분지시기물원주요래자우기련—북진령도호잡암대，588～1548Ma화1612～2496Ma적년령조분반영적물원주요래자우북진령조산대，기련조산대화화북판괴기저。③고석년령보종합분석，평량조쇄설침적물질래원복잡，구유명현적다원성，지시만오도세평량기적침적배경응속우기련—북진령도호잡암대여악이다사지괴서남연지간적국한잔류변연해분지。
The U-Pb ages of single zircon grains contained in the sandstone samples were analyzed by the LA-ICP-MS method,the sediment provenances and geological significance were discussed.The results show that:①The detrital zircon age of the tuffaceous sandstone from the Upper Ordovician Pingliang Formation can be obviously divided into three groups,the first group is Early Paleozoic which ranges from 407 ~477Ma,the peak value is 454Ma,accounting for about 72.5% of the total dates.The second group is Meso—Neoproterozoic which ranges from 588~1548Ma,the peak value is 962Ma,accounting for about 22.5% of the total dates.The last group is Paleoproterozoic which ranges from 1612 ~2496Ma,accounting for about 5% of the total dates.② The group of 407~477 Ma indicates that its material provenances may mainly come from the North Qinling—Qilian island-arc complex belt in adjacent regions.The group between 588~1548Ma and 1612~2496Ma indicates that its material provenances were mainly from the North Qinling orogenic belt and the Qilian orogenic belt,with the little of material from the basement of North China block.③A comprehensive analysis shows that the material provenances of Pingliang Formation were much more complicated and characterized by obvious diversity and complexity.The indication is that sedimentary environment is the limits of residual marginal sea basin between North Qinling—Qilian island-arc complex belt and the southwest of Ordos block in the Pingliang age Ordovician.