| 陕西富平上奥陶统赵老峪组硅质岩地化特征及地质意义 |
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| 引用本文： | 史毅,屈红军,李文厚,杜美迎,王浩.陕西富平上奥陶统赵老峪组硅质岩地化特征及地质意义[J].地球科学,2020,45(1):168-179. |
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| 作者姓名： | 史毅 屈红军 李文厚 杜美迎 王浩 |
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| 作者单位： | 1.西北大学大陆动力学国家重点实验室, 陕西西安 710069 |
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| 基金项目： | 国家重点研发计划项目2016YFC0601003国家自然科学基金面上项目41172101国家科技重大专项2016ZX05026-007 |
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| 摘 要： | 陕西富平上奥陶统赵老峪组发育了一套与深水碳酸盐岩伴生的硅质岩沉积，其地化特征对揭示硅质来源及构造背景等具有重要意义.在研究区地层野外剖面实测、硅质岩岩石地化分析基础上，研究了该区硅质岩硅质来源及构造环境.赵老峪组岩性以深灰色薄板状灰岩为主，夹层状放射虫硅质岩、砾屑灰岩、砂屑灰岩、含斑块灰岩和火山凝灰岩，其中硅质岩呈隐晶质－微晶质，含放射虫化石.样品Al/（Al+Fe+Mn）均值0.68，MnO/TiO2均值0.18，ΣREE均值46.41，δCe均值0.95，δEu均值1.13，LaN/YbN均值1.15，LaN/CeN均值1.08，显示大陆边缘的构造环境，硅质来源主要为陆源来源.结果表明赵老峪组硅质岩发育于奥陶纪扬子板块向华北板块俯冲背景下，形成于华北地块南缘与北秦岭之间的二郎坪弧后前陆盆地北部大陆边缘.
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| 关 键 词： | 硅质岩 上奥陶统 赵老峪组 富平地区 二郎坪弧后前陆盆地 地球化学 |
| 收稿时间： | 2018-09-06 |
Geochemical Characteristics and Geological Significance of Siliceous Rocks in Upper Ordovician Zhaolaoyu Formation in Fuping Region,Shaanxi Province |
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| Abstract: | In Fuping region of Shaanxi Province, a suite of radiolarian siliceous rocks is developed in Upper Ordovician Zhaolaoyu Formation, which is associated with deep water carbonate rocks. The geochemical characteristics of siliceous rocks are of great significance in revealing the source of silicon and tectonic setting. On basis of the field profile, the petrological and geochemical analyses of siliceous rocks in Upper Ordovician Zhaolaoyu Formation in Fuping region, the origin and tectonic setting are studied. It is found that Zhaolaoyu Formation is dominated by dark gray lamellose limestone, with lamellar radiolarian siliceous rocks, conglomerate limestone, calcarenite, patchy limestone and volcanic tuff. Siliceous rocks are cryptocrystalline-microcrystalline, containing radiolarian fossils. The geochemical test of the samples yields the value of Al/(Al+Fe+Mn) (average 0.68), MnO/TiO2 (average 0.18), ΣREE (average 46.41), δCe (average 0.95), δEu (average 1.13), LaN/YbN (average 1.15), LaN/CeN (average 1.08), suggesting that the tectonic environment is continental margin and the silicons are mainly of terrigenous origin. We believe that the siliceous rocks in Fuping region were formed on the northern margin of the Erlangping retroarc foreland basin, which was formed between the southern margin of North China Block and the North Qinling under the background of subduction of the Yangtze Plate to the North China Plate during the Ordovician. |
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