大兴安岭北段呼玛地区晚侏罗世花岗闪长岩年代学和地球化学特征:对蒙古—鄂霍茨克洋构造演化的制约
Geochronology and geochemistry of Late Jurassic granodiorite in Huma area of northern segment of Da Hinggan Ling(Mts.):constraints on tectonic evolution of Mongolia-Okhotsk Ocean
孔金贵 1张国宾 2张文东 3王七林 3董佳松 3陈兴凯 4何云龙5
作者信息
- 1. 山东省核工业二七三地质大队,山东烟台 264000;辽宁工程技术大学地质科学与工程系,辽宁阜新 123000
- 2. 辽宁工程技术大学地质科学与工程系,辽宁阜新 123000;山西工程技术学院地球科学与工程系,山西阳泉 045000
- 3. 山东省核工业二七三地质大队,山东烟台 264000
- 4. 江苏煤炭地质物测队,南京 210000
- 5. 辽宁工程技术大学地质科学与工程系,辽宁阜新 123000
- 折叠
摘要
大兴安岭北段地区晚中生代花岗岩极其发育,但该区岩浆活动期次、岩石组合及成岩动力学机制一直是地学界争议的科学问题.笔者对大兴安岭北段呼玛地区中细粒花岗闪长岩进行了系统锆石U-Pb同位素年代学和全岩元素组成研究,探讨岩石成因和岩浆源区,分析成岩构造环境并尝试限定蒙古—鄂霍茨克洋闭合时限.研究结果显示,花岗闪长岩成岩时代为(149.9±1.7)Ma,属于晚侏罗世.花岗闪长岩具有富 Si、Al,贫 Mg、Y、Yb(w(Y)≤18 × 10-6,w(Yb)≤1.9 × 10-6),高Sr(w(Sr)＞400×10-6)的特征,A/CNK为1.01～1.15,属于高钾钙碱性岩石系列,相对富集Rb、Ba、K、La、Ce、Sr元素,亏损Ta、Nb、P、Ti、Y、Yb、Lu元素,微弱Eu正异常,属于"C"型埃达克岩.结合区域岩浆锆石Nd同位素组成特征,表明岩浆来源于新元古代晚期—显生宙新增生下地壳角闪岩相物质的部分熔融.综合年代学、地球化学特征和区域构造演化,认为大兴安岭北段呼玛地区晚侏罗世花岗闪长岩形成于后碰撞隆起构造环境,与蒙古—鄂霍茨克洋闭合作用密切相关.
Abstract
In the northern segment of the Da Hinggan Ling(Mts.),Late Mesozoic granites are highly deve-loped.However,the volcanic activity periods,rock compositions,and petrogenetic mechanism in this area have been controversial in the field of earth sciences.The authors systematically conducted zircon U-Pb isotope geo-chronological and whole-rock elemental composition studies on the medium-fine grained granodio-rite in the Huma area of the northern segment of the Da Hinggan Ling(Mts.),and aimed to investigate rock genesis and magmatic source regions,analyze the tectonic setting of rock formation,and attempt to constrain the timing of the closure of the Mongol-Okhotsk Ocean.The research results indicate that the crystallization of the granodiorite is(149.9±1.7 Ma),which is the Late Jurassic.The granodiorite is rich in Si and Al,but poor in Mg,Y and Yb(w(Y)≤18 × 10-6,w(Yb)≤1.9 × 10-6),has high Sr content(w(Sr)＞400 × 10-6)and A/CNK of 1.01-1.15,belonging to the high-K calc-alkaline rock series.It is relatively enriched in Rb,Ba,K,La,Ce and Sr elements,and depleted in Ta,Nb,P,Ti,Y,Yb and Lu elements,with a weak positive Eu anomaly.It belongs to the"C"type Adakite.Combined with the regional magmatic zircon Nd isotopic composition characteristics,the data indicate that the magma originated from the partial melting of accretionary lower crustal amphibolite-facies material during the Late Neoproterozoic to Phanerozoic.Combining geochronological,geochemical characteristics,and regional tectonic evo-lution,it is suggested that the Late Jurassic granodiorite in the Huma area of the northern segment of the Da Hing-gan Ling(Mts.)formed in a post-collision uplift tectonic environment and is closely related to the closure of the Mongol-Okhotsk Ocean.
关键词
花岗闪长岩/锆石U-Pb年龄/岩石地球化学/构造背景/晚侏罗世/大兴安岭北段Key words
granodiorite/zircon U-Pb age/petrogeochemistry/tectonic setting/Late Jurassic/northern seg-ment of Da Hinggan Ling(Mts.)引用本文复制引用
基金项目
中国地调局项目(1212011120342)
辽宁省科技厅面上基金(20170540428)
辽宁省科技厅面上基金(201601370)
辽宁省教育厅面上项目(LJ2019JL027)
出版年
2024
NETL
NSTL
万方数据