北山造山带北部晚古生代岩浆记录及其对百合山洋演化的约束OA
Late Paleozoic magmatic records from northern Beishan orogenic belt and their constraints on the evolution of the Baiheshan Ocean
[研究目的]本文旨在明确北山造山带北部百合山洋演化过程中地幔源区性质及岩浆记录,从而为理解增生造山带的演化机制提供关键依据.[研究方法]通过对红柳峡地区新识别岩体进行系统的锆石 U-Pb 定年、全岩主量、微量元素及 Sr-Nd-Hf 同位素分析.[研究结果]在蛇绿混杂岩带南部红柳峡地区新识别出一套侵位于 320±3 Ma 的辉绿玢岩,是百合山洋主俯冲期的产物.岩石显示高钾钙碱性地球化学性质,具有富集 Rb、Th、U、Sr 等大离子亲石元素及轻稀土元素,亏损 Nb、Ta、Ti 等高场强元素的弧岩浆岩特征.辉绿玢岩 εNd(t)值介于 3.09～4.29 之间,εHf(t)值介于 5.8～12.3 之间,暗示岩浆起源于亏损地幔的部分熔融,Yb、La、Sm 元素共同约束其可能为石榴子石二辉橄榄岩部分熔融的产物.母岩浆在形成后经历了有限的分离结晶并受到不同程度地壳混染的影响.早二叠世岩浆作用代表百合山洋俯冲末期的构造-岩浆事件.大范围分布的斑状二长花岗岩的形成时代为 275.6±1.4 Ma,属于高钾钙碱性 I 型花岗岩.岩石富集 Rb、Th、U 等大离子亲石元素及轻稀土元素,亏损 Nb、Ti 等高场强元素.岩石 εHf(t)值介于 9.1～14.6 之间,二阶段模式年龄介于 368～719 Ma 之间,是新元古代—古生代新生下地壳部分熔融的产物.[结 论]结合区域地质资料,北山造山带北部增生造山作用应结束于早—中二叠世.
[Objective]This study aims to clarify the nature of the mantle source and the magmatic record during the evolution of the Baiheshan Ocean in the north Beishan Orogenic Belt,thereby providing key evidence for understanding the evolution mechanism of accretionary orogens.[Methods]This paper presents systematic zircon U-Pb dating,whole-rock major and trace element,and Sr-Nd-Hf isotopic analyses of newly identified intrusive rocks in the Hongliuxia area.[Results]This work has identified a new set of sillite intruded at 320±3 Ma in the Hongliuxia area of the southern ophiolitic melange belt,which is the product of the major subduction of the Baiheshan Ocean.The sillite shows high-K calc-alkaline geochemical characteristic and was enriched in large-ion lithophile elements like Rb,Th,U,Sr and light rare earth elements and depleted in high field strength elements like Nb,Ta,Ti,showing characteristics of arc magmatic rocks.The values of εNd(t)and εHf(t)of the sillite range from 3.09 to 4.29 and 5.8 to 12.3 respectively,implying that the magma originated from depleted mantle.It may be the product of partial melting of garnet dipyroperidotite constrained by Yb,La and Sm elements.The primary magma underwent limited fractional crystallization and various degrees of crustal contamination.The Early Permian magmatism represents the tectono-magmatic event at the end of the subduction of Baiheshan Ocean.In this work,the widely distributed porphyritic monzogranite was intruded at 275.6±1.4 Ma,belonging to high-K calc-alkaline I-type grantie.They are enriched in large-ion lithophile elements like Rb,Th,U and light rare earth elements and depleted in high field strength elements like Nb,Ti.The values of εHf(t)and TDM2of the porphyritic monzogranite vary from 9.1 to 14.6 and 368 to 719 respectively,implying magma originated from partial melting of the juvenile crust from Neoproterozoic to Paleozoic.[Conclusions]Combined with regional geological material,the accretionary orogeny in the northern part of the Beishan orogenic belt should have ended in the early to middle Permian.
张国震;辛后田;田健;刘晨成;牛文超;王明明;段连峰
中国地质调查局天津地质调查中心,天津 300170||华北地质科技创新中心,天津 300170中国地质调查局天津地质调查中心,天津 300170||华北地质科技创新中心,天津 300170中国地质调查局天津地质调查中心,天津 300170||华北地质科技创新中心,天津 300170山东省物化探勘查院,山东 济南 250013中国地质调查局天津地质调查中心,天津 300170||华北地质科技创新中心,天津 300170山东地矿新能源有限公司,山东 济南 250001中国地质调查局天津地质调查中心,天津 300170||华北地质科技创新中心,天津 300170
天文与地球科学
辉绿玢岩晚古生代地球化学Sr-Nd-Hf同位素北山造山带
silliteLate PaleozoicgeochemistrySr-Nd-Hf isotopeBeishan orogenic belt
《地质通报》 2026 (4)
720-739,20
地球深部探测与矿产资源勘查国家科技重大专项(编号:2025ZD1005705),中国地质调查局项目《燕山-太行成矿带中条山地区铜钴矿产地质调查》(编号:DD20230272)、《华北地区区域基础地质调查》(编号:DD20211339) Supported by Deep Earth probe and Mineral Resources Exploration-National Science and Technology Major Project(No.2025ZD1005705),and the projects of China Geological Survey(Nos.DD20230272,DD20211339)
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