| 云开地块东缘寒武系-泥盆系不整合界面上下的碎屑锆石U-Pb年代学记录及对物源转换的响应 |
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| 引用本文： | 王志宏,杨文强,周岱,牛志军,何垚砚,宋芳.云开地块东缘寒武系-泥盆系不整合界面上下的碎屑锆石U-Pb年代学记录及对物源转换的响应[J].地球科学,2018,43(11):4193-4203. |
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| 作者姓名： | 王志宏 杨文强 周岱 牛志军 何垚砚 宋芳 |
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| 作者单位： | 1.中国地质调查局武汉地质调查中心, 湖北武汉 430205 |
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| 基金项目： | 中国地质调查局项目121201209000160035中国博士后科学基金项目2017M612537国家自然科学基金项目41772019 |
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| 摘 要： | 云开地块东缘粤西圭岗镇附近寒武系之上不整合覆盖一套灰白色石英砾岩-含砾砂岩，由于缺乏化石和年龄依据，这套岩石的时代长期存有争议.利用LA-ICP-MS U-Pb测年手段，对该套含砾碎屑沉积岩及其上下层位进行了U-Pb测年，4件样品共获得300组有效数据，年龄变化于2 900~400 Ma，不整合面之下样品主要集中于1 100~700 Ma，不整合面之上最年轻碎屑锆石年龄集中于450~400 Ma.新的测年数据结合前人研究成果表明，云开地块东缘不整合面下伏及上覆地层的时代分别为寒武纪和泥盆纪.研究区寒武纪时期物源特征与印度、东南极洲和澳大利亚西部相似，指示该时期研究区同冈瓦纳东北缘相连，物源来自东冈瓦纳北缘南极洲、印度地块和澳大利亚之间的造山带，而泥盆纪物源主要来自邻近的云开地块.寒武系和泥盆系之间的不整合面是早古生代郁南运动与广西运动叠加的产物.
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| 关 键 词： | 云开地块 碎屑锆石 郁南运动 广西运动 年代学 沉积学 |
| 收稿时间： | 2018-08-12 |
Detrital Zircon U-Pb Geochronological Records and Its Response of Provenance Transformation of Strata Surrounding Cambrian-Devonian Unconformity in Eastern Margin of Yunkai Massif |
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| Abstract: | The unconformity of the Cambrian in the eastern margin of the Yunkai massif near Guigang, West Guangdong covers a set of gray-white quartz conglomerate-gravel sandstones. Due to the lack of fossils and U-Pb dating, the age of the stratum has remained controversial for a long time. By LA-ICP-MS U-Pb dating, a total of 300 valid data were obtained from 4 samples with age ranging from 2 900-400 Ma in this study. The samples below the unconformity surface are mainly concentrated at 1 100-700 Ma, and the youngest detrital zircon ages above the unconformity surface are concentrated at 450-400 Ma. The new dating data combined with previous research show that the ages of underlying and overlying strata in Guigang are Cambrian and Devonian, respectively. The source characteristics of the Cambrian are similar to those of the orogenic zone among India, eastern Antarctica and Australia. While the Devonian sources are relatively homogeneous, derived from the adjoining Yunkai massif. It is proposed that the unconformity of the study area should have resulted from the superposition of the Yu'nan orogeny and the Guangxi orogeny. |
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