| 中蒙边境中段花岗岩时空分布特征及构造和找矿意义 |
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| 引用本文：童英,洪大卫,王涛,史兴俊,张建军,曾涛.2010.中蒙边境中段花岗岩时空分布特征及构造和找矿意义[J].地球学报,31(3):395-412. |
| DOI：10.3975/cagsb.2010.03.13 |
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| 基金项目:国家自然科学基金项目(编号: 40702010); 地质调查项目(编号: 200113900018；12123206043；1212010611817); 国家重点基础研究发展计划(编号: 2009CB825006) |
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| 中文摘要:本文精确地厘定了中蒙边境中段白乃庙片麻状石英闪长岩(459-454 Ma)、锡林浩特代托吉卡山中粒晶洞正长花岗岩(268±6.9 Ma)、镶黄旗巴音察汗灰白色中细粒角闪黑云母花岗闪长岩(261.7±6.1 Ma)、镶黄旗二长花岗岩(262.7±6.0 Ma)、镶黄旗哈达庙黑云母石英闪长岩(277.2±2.9 Ma)、锡林浩特白音锡勒中细粒正长花岗岩(231.1±7.6 Ma)、苏尼特左旗(东苏)二长花岗岩(216.9±5.4 Ma)、苏尼特左旗沙尔塔拉碱长花岗岩(152.1±2.5 Ma)的时代。并在前人工作的基础上, 总结了本地区花岗岩的时空分布规律: 区内花岗岩空间上呈3条近东西向的条带分布, 时间上可划分为5个重要期次:早-中古生代(490-387 Ma)、石炭纪(342-302 Ma)、二叠纪(282-257 Ma)、三叠纪(249-204 Ma)和晚中生代(152-118 Ma), 峰期间隔约为40 Ma, 并存在两条巨型碱性花岗岩带(东乌珠穆沁旗一带的二叠纪碱性岩带、华北板块北缘的晚三叠世碱性正长岩带), 岩浆活动呈现不对称性。结合区域地质、岩石、年代学等证据说明, 北部贺根山蛇绿岩与南部索伦山-西拉木伦蛇绿岩代表两个洋盆体系, 贺根山洋闭合早于中二叠世, 而索伦山-西拉木伦缝合带所代表残留古亚洲洋关闭, 中朝板块与西伯利亚板块最终碰撞拼合的时代应在晚二叠世-早三叠世。同时, 区内与花岗岩有关的矿产发育, 包括铜、钨、锌等矿种, 多产于造山后伸展或岩石圈拆沉, 区域大规模伸展环境。 |
| 中文关键词:古亚洲洋 花岗岩 年代学 构造演化 成矿 |
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| Spatial and Temporal Distribution of Granitoids in the Middle Segment of the Sino-Mongolian Border and Its Tectonic and Metallogenic Implications |
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| Abstract:Zircon U-Pb dating of the granitoids in the middle segment of the Sino-Mongolian border has yielded ages of 459-454Ma (Bainaimiao gneissic quartz diorite), 268±6.9Ma (Daituojikashan miarolitic syenogranite of Xilin Hot), 261.7±6.1 Ma (Baiyichagan hornblende biotite granodiorite of Xianghuang Banner), 262.7±6.0 Ma (Xianghuang Banner monzogranite), 277.2±2.9 Ma (Hadamiao biotite quartz diorite of Xianghuang Banner), 231.1±7.6 Ma (Bayanxile syenogranite of Xilin Hot), 216.9±5.4 Ma (Sonid Left Banner/Dongsu monzogranite) and 152.1±2.5 Ma (Shaertala alkali feldspar granite of Sonid Left Banner), respectively. Based on these ages and the chronological data already available, the authors hold that the granitoids have regular spatial and temporal dis-tribution, i.e., the granitoids were emplaced along three main belts and the intrusive epoch can be divided into five major stages, namely Early-Middle Paleozoic (490-387 Ma), Carboniferous (342-302 Ma), Permian (282-257 Ma), Triassic (249-204 Ma) and Late Mesozoic (152-118 Ma). There exist two giant alkaline granite belts in this area, i.e., Permian alkaline granite belt near Dongwuzhumuqin and Late Triassic alkaline syenite belt along the northern margin of North China Craton, with magmtic activities being asymmetric. Regional geological, petrological and chronological evidence indicates that the Hegenshan ophiolite belt near the southern margin of the Siberian plate and Solonker-Xaro Morn ophiolite belt near the northern margin of Sino-Korean plate represent two oceans respectively. The Hegenshan Ocean was closed before middle Permian, and the Solonker-Xaro Morn Ocean (residual Paleo-Asian Ocean) was closed during the Late Permian-Early Triassic period, and the terminal collision between Sino-Korean and Siberian plates should have occurred at this time. Lots of granite-related mineral deposits have been found in this area, which include copper, tungsten, zinc and other deposits, produced mostly in the regional large-scale extensional setting of the post-orogenic or lithosphere delamination. |
| keywords:Paleo-Asian Ocean granitoid chronology structural evolution mineralization |
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