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对广西东部大瑶山-大明山地区分别位于早古生代不整合面之下和之上的寒武纪和泥盆纪地层进行了系统的碎屑锆石U-Pb同位素年代学研究.除少数为早太古宙锆石外,寒武纪地层碎屑锆石的年龄主要有2.7～2.6、～1.8、1.4～1.1和～1.0Ga四组峰值及分别为250Ma和105Ma的热液改造年龄记录;泥盆纪地层碎屑锆石除少数具有古太古代年龄外,其余主要形成于～1.7和～1.0Ga,并记录了强烈的～100Ma的热改造事件.这些特征表明,研究区具有华夏陆块的属性,扬子与华夏陆块的边界应位于该区西北以远;经加里东构造事件后,研究区沉积盆地的物源区发生了改变,因而加里东期岩浆作用在本区并没有显示.结合前人研究成果分析,加里东事件可能指示了已裂开古陆块与华夏陆块间发生的斜向碰撞,而大瑶山-大明山地区为沿垂直于该碰撞方向挤压形成的被动盆地.区域地层中部分碎屑锆石U-Pb同位素组成的重置和热液锆石的形成,反映了研究区在印支期和燕山期存在大规模流体参与的热改造事件,这些热液对流作用应是导致本地区乃至整个华南褶皱带陆缘Au-Cu多金属矿带形成的重要原因之一.
We systematically studied the zircon detrital zircon U-Pb isotopic dating of the Cambrian and Devonian strata respectively located in and below the Early Paleozoic unconformities in the Dayaoshan-Damingshan area in the eastern part of Guangxi. Except for a few The ages of the detrital zircons in the Cambrian strata are mainly 2.7 ~ 2.6, ~ 1.8, 1.4 ~ 1.1 and ~ 1.0Ga, and the hydrothermal alteration age records are 250Ma and 105Ma respectively. The zircons from the basin are all formed mainly at ~1.7 and ~1.0Ga except for a few with Paleolithic age, and intense ~ 100 Ma thermal remodeling events are recorded. These characteristics indicate that the study area has the features of the Huaxia land mass The boundary between the Yangtze and Huaxia terrane should be located beyond the northwest of the area. After the Caledonian structural event, the provenance area of the sedimentary basin in the study area changed, so the Caledonian magmatism did not show in this area. According to the results of previous studies, the Caledonian event may indicate the oblique collision between the fractured paleocontinent block and the Huaxia terrane, while the Dayaoshan-Damingshan area is a passive basin formed by extrusion perpendicular to the collision direction Partially detrital zircons in regional formations The reset of U-Pb isotopic composition and the formation of hydrothermal zircon reflect the thermal remodeling events in the study area during the Indosinian and Yanshanian periods where large-scale fluids are involved. These hydrothermal convection effects should result in the occurrence of hydrothermal convection in the region as well as the entire South China One of the important reasons for the formation of continental Au-Cu polymetallic ore belt in the fold belt is that the