Early Paleozoic Volcanism in Nuomuhongguole Area, East Kunlun Orogenic Belt
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摘要: 诺木洪郭勒一带发育早古生代火山岩, 可明显分为2种类型: 一类为基性火山岩组合, 岩石主要为具枕状构造的玄武岩, SiO2碱度均较低, 为拉斑系列玄武岩, 稀土、微量元素特征及构造环境判别显示其形成于洋中脊的构造环境; 另一类为中基性火山岩组合, 火山岩岩石类型复杂, 熔岩和火山碎屑岩均较发育, 熔岩成分从基性到中酸性均有, 火山岩SiO2成分变化较大, 既有亚碱性, 又有碱性, 亚碱性系列岩石多属钙碱性系列.稀土、微量元素特征及构造环境判别其形成于火山弧的环境.Abstract: Early Paleozoic volcanic rocks developed in Nuomuhong area can be devided into two types. One is the basic volcanic assemble, mainly consisting of tholeiite basalts with low SiO2 and alkali. Its characteristics of REE, trace elements and tectonic setting reveal that it formed in middle ocean ridge tectonic setting. The other is called middle-basic volcanic assemble with complex rock types and well developed lava and pyroclastics. The volcanic rocks belong to subalkali and alkali series, and the subalkali rocks belong to calalkali series. The charecteristics of REE, trace elements and tectonic setting indicate that they formed in volcanic arc tectonic setting.
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Key words:
- East Kunlun orogenic belt /
- Early Paleozoic /
- volcanic rock /
- Nuomuhongguole area
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图 1 诺木洪地区地质简图
1.第四纪冲洪积物; 2.早侏罗世羊曲组; 3.晚三叠世八宝山组; 4.早中三叠世洪水川组; 5.早石炭世哈拉郭勒组; 6~9.早古生代纳赤台群; 6.基性火山岩组合; 7.中基性火山岩组合; 8.碎屑岩组合; 9.碳酸岩组合; 10.狼牙山组; 11.苦海岩群; 12.中三叠世二长花岗岩; 13.中三叠世花岗闪长岩; 14.中三叠世浆混花岗岩; 15.中石炭世二长花岗岩; 16.早石炭世钾长花岗岩; 17.早泥盆世二长花岗岩; 18.中志留世辉石闪长岩; 19.玄武岩; 20.中基性火山岩; 21.强片理化中基性火山岩; 22.强片理化火山碎屑岩; 23.大理岩; 24.强片理化碎屑岩; 25.变硅质岩糜棱岩; 26.眼球状片麻岩; 27.糜棱岩; 28.超镁铁质岩; 29.逆断层; 30.斜冲断层; 31.正断层
Fig. 1. Sketch geological map of Nuomuhong area
图 3 早古生代中基性火山岩组合实测剖面
1.砂岩; 2.石英砂岩; 3.长石砂岩; 4.泥质粉砂岩; 5.泥质岩; 6.灰岩; 7.结晶灰岩; 8.硅质岩; 9.斜长角闪岩; 10.辉绿岩; 11.闪长岩; 12.石英闪长岩; 13.辉石闪长岩; 14.玄武岩; 15.杏仁状玄武岩; 16.安山岩17.玻基安山岩; 18.石英安山岩; 19.英安岩; 20.流纹斑岩; 21.英安流纹斑岩; 22.凝灰岩; 23.晶屑凝灰岩; 24.玻屑凝灰岩; 25.玄武质凝灰岩; 26.含火山角砾晶屑凝灰岩; 27.安山质凝灰角砾岩; 28.安山质火山角砾岩; 29.板岩; 30.斑点状板岩; 31.粉砂质板岩; 32.硅质板岩; 33.凝灰质板岩; 34.大理岩; 35.石英片岩; 36.绿泥绿帘片岩; 37.片理化; 38.断层角砾岩及碎裂岩化; 39.断层; 40.产状
Fig. 3. Section of metavolcanic slice of Early Paleozoic
图 5 早古生代火山岩TAS图[4]
B.玄武岩; O1.玄武安山岩; O2.安山岩; O3.英安岩; R.流纹岩; S1.粗面玄武岩; S2.玄武质粗面安山岩; S3.粗面安山岩; 其他符号略(图中碱性亚碱性界线据Irvine和Barager[5]); ▲基性火山岩组合(斜线区); ●中基性火山岩组合(竖线区)
Fig. 5. TAS diagram of Early Paleozoic volcanic rocks
图 6 早古生代火山岩AFM图[5]
T.拉斑玄武岩系列; C.钙碱性系列; ▲基性火山岩组合; ●中基性火山岩组合
Fig. 6. AFM diagram of Early Paleozoic volcanic rocks
图 10 早古生代火山岩w (Y/15) -w (La/10) -w (Nb/8) 图
1.火山弧: 1A.钙碱性玄武岩; 1B.地渡区; 1C.火山弧拉斑玄武岩; 2.大陆玄武岩: 2A.大陆玄武岩; 2B.弧后盆地玄武岩; 3.大洋玄武岩: 3A.陆内裂谷碱性玄武岩; 3B, 3C.E-MORB型(B富集, C略富集); 3D.N-MORB型; 基性火山岩组合: ●玄武岩; 中基性火山岩组合: ▲玄武岩; ■玄武质粗面安山岩
Fig. 10. Diagram of w (Y/15) -w (La/10) -w (Nb/8) of Early Paleozoic volcanic rocks
表 1 早古生代纳赤台混杂岩群火山岩化学分析结果
Table 1. Chemical analysis results of Early Paleozoic volcanic rocks
表 2 早古生代纳赤台混杂岩群火山岩稀土元素分析结果及球粒陨石标准化值
Table 2. Analysis results of REE and meteorite standardized values of Early Paleozoic volcanic rocks
表 3 早古生代火山岩微量元素分析结果及MORB标准化值
Table 3. Analysis results of trace elements and MORB standardized values of Early Paleozoic volcanic rocks
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