海拉尔盆地火山岩的锆石U-Pb年龄及其地质意义

发布时间：2018-01-15 13:43

本文关键词：海拉尔盆地火山岩的锆石U-Pb年龄及其地质意义　出处：《地球科学》2016年08期 　论文类型：期刊论文

【摘要】：海拉尔盆地位于大兴安岭西侧,盆内存在多套火山-沉积岩组合.通过对海拉尔盆地Chu8井等4处火山岩样品进行的锆石LA-ICP-MS U-Pb年代学研究,探讨了海拉尔盆地火山岩的形成时代和构造背景,为盆内和邻区地层对比以及大兴安岭地区构造演化提供了依据.研究区4个火山岩样品的锆石均呈自形-半自形晶,显示出典型的岩浆生长环带,结合其高的Th/U比值(0.22~1.50),说明其属于岩浆成因.测年结果表明,海拉尔盆地布达特群确实存在时代为晚三叠世-早侏罗世(214.4±4.3Ma)的火山岩,结合前人研究,可将盆内火山作用划分为4期:分别为中-晚石炭世基底岩浆岩(320~290Ma);晚三叠世-早侏罗世早期布特达特群火山碎屑岩组(224~197Ma);晚侏罗世-早白垩世早期塔木兰沟组(152~138Ma);早白垩世晚期铜钵庙组(128~117Ma).大兴安岭地区各期岩浆作用的地球化学特征、时空分布特征以及盆地地震剖面特征表明,中-晚石炭世基底岩浆岩(320~290Ma)是额尔古纳-兴安地块和松嫩地块碰撞造山后的伸展背景下形成的;晚三叠世-早侏罗世早期火山岩(224~197Ma)是古亚洲洋闭合后的伸展背景下形成的,该期火山岩的发现说明古亚洲洋构造域对大兴安岭地区的影响至少延续到早侏罗世早期(197Ma),而该区域蒙古-鄂霍茨克洋的俯冲碰撞最早可能开始于早侏罗世以后;晚侏罗世-早白垩世早期(152~138Ma)和早白垩世晚期(128~117Ma)火山岩的形成均与蒙古-鄂霍茨克洋碰撞闭合后的伸展作用有关.盆内部分火山岩样品中存在古元古代-新元古代捕获的锆石,这表明额尔古纳地块和兴安地块很可能存在着元古代结晶基底.
[Abstract]:The Hailar Basin is located on the west side of the Great Xing'an Mountains. There are several volcanic-sedimentary rock assemblages in the basin. Zircon LA-ICP-MS U-Pb chronology has been carried out on four volcanic rock samples from Chu8 well in Hailaer Basin. The formation age and tectonic background of volcanic rocks in Hailaer Basin are discussed. It provides the basis for the stratigraphic correlation in the basin and adjacent areas and the tectonic evolution of the Daxinganling area. The zircon of the four volcanic rock samples in the study area all show a magmatic growth ring. Combined with its high Th/U ratio of 0.22 ~ 1.50%, it belongs to magmatic origin, and the dating results show that it belongs to magmatic origin. The Budate Group in Hailaer Basin did exist in the late Triassic-early Jurassic volcanic rocks (214.4 卤4.3 Ma.), combined with previous studies. The volcanism in the basin can be divided into four periods: Middle-late Carboniferous basement magmatic rocks 320 ~ 290 Ma; Late Triassic-early Jurassic volcanic clastic rock formation of the Bout Datt Group, China; Late Jurassic-early Cretaceous Tamulangou formation, 152D138Mahe; In the late early Cretaceous Tongpumiao formation, the geochemical characteristics, temporal and spatial distribution of magmatism in each stage of the Daxing'anling area and the seismic profile of the basin are indicated. The Middle-Late Carboniferous basement magma was formed in the extensional setting after the collision orogeny between the Erguna-Xingan block and the Songnen block. The late Triassic-Early Jurassic volcanic rocks were formed in the Paleo-Asian Ocean after the closure of the Paleo-Asian Ocean. The discovery of volcanic rocks in this period indicates that the influence of the Paleo-Asian oceanic tectonic domain on the Daxing'anling area continued at least until the early Jurassic period (197MaA). The subduction collision of the Mongolia-Okhotsk ocean in the region may have started after the early Jurassic. Late Jurassic-early Cretaceous (152Cretaceous 138Ma) and late early Cretaceous (128U 117Ma). The formation of volcanic rocks is related to the extension after the closure of the Mongolia-Okhotsk ocean collision. Some volcanic samples in the basin contain zircon from Paleoproterozoic to Neoproterozoic. This suggests that there is probably a Proterozoic crystalline basement in the Erguna and Xingan massifs.
【作者单位】：辽宁石油化工大学石油天然气工程学院;吉林大学地球科学学院;吉林大学古生物学与地层学研究中心;大庆油田有限责任公司勘探开发研究院;重庆科技学院石油与天然气工程学院;
【基金】：国家重点基础研究发展计划(973计划)项目(No.2012CB822002) 国家自然科学基金项目(No.41202072)
【分类号】：P588.14;P597.3
【正文快照】： 大兴安岭地区位于兴蒙造山带东段,是由众多微板块(包括额尔古纳地块、兴安地块和松嫩地块)拼贴所形成的统一陆块群(图1),古生代晚期经历了古亚洲洋的消减闭合(Chen et al.,2000;刘敦一等,2003;葛文春等,2005a;Jian et al.,2008),中生代以来又受到蒙古-鄂霍茨克构造域和太平洋

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