中国地质调查局:内蒙古白音敖包幅(L50E024024)1∶50000地质图数据库

内蒙古白音敖包幅（L50E024024）处于额尔齐斯-西拉木伦对接带的重要地段，本次重新厘定了地层层序，共划分9个组级岩石地层单位，8个第四系成因类型填图单位。建立了上二叠统巴彦花海相火山－沉积岩（P3bh）非正式填图单位，在安山质凝灰岩中获得LA-ICP-MC-MS锆石U-Pb年龄251.5±2.1 Ma；首次识别出上二叠统林西组，主要为一套半深湖相和滨浅湖相沉积碎屑岩，在林西组内新填绘出4层暗色泥岩；首次识别出下三叠统老龙头组，主要为一套紫红色碎屑岩夹少量酸－中性火山碎屑（熔）岩，获得安山质凝灰岩LA-MC-ICP-MS锆石U-Pb年龄为246.0±1.1Ma；对中侏罗统新民组进行了重新厘定，主要为一套沉积碎屑岩夹酸性火山岩，偶见煤线。在粉砂岩中发现芦木类植物及硅化木化石，在粗砂岩中采集2件孢粉样品，为禾本科（1粒）、松属（3粒）花粉。获得流纹质晶屑玻屑凝灰岩LA-MC-ICP-MS锆石U-Pb年龄为158.0±1.7Ma；重新厘定了上侏罗统满克头鄂博组，主要为一套陆相酸性火山岩、火山碎屑岩。获得流纹质晶屑玻屑熔结凝灰岩LA-MC-ICP-MS锆石U-Pb年龄为152.7±1.7Ma；重新厘定了下白垩统玛尼吐组，主要为一套陆相中性火山岩、火山碎屑岩及沉积碎屑岩。获得安山岩LA-MC-ICP-MS锆石U-Pb年龄为135.4±1.2Ma；重新厘定了下白垩统白音高老组，为一套陆相酸性火山岩建造，获得流纹岩LA-MC-ICP-MS锆石U-Pb年龄分别为131.0±1.8Ma；首次识别出下白垩统龙江组和光华组，并在龙江组安山岩内获得为129.6±1.7 Ma；在巴彦宝勒日-胜利村一带识别出一套早白垩世二长花岗岩岩体，并获得LA-MC-ICP-MS锆石U-Pb年龄为126.4±0.86 Ma。 运用火山地层-岩性岩相-火山构造三重填图法，在白音敖包地区划分火山盆地2个，火山机构5个、火山口8个及6个火山喷发旋回。 获得了第四系沉积物多组光释光年龄，分别为赤峰黄土时代为（>135.4±9.0）ka BP，属于中更新世晚期；乌尔吉组的时代为（>130.6±9.2~55.5±3.8）ka BP，属于晚更新世早中期；洪冲积物的时代为（5.5±0.3）ka BP，属于中全新世晚期。 通过对第四系松散沉积物粒度、磁化率、碳酸盐及所含孢粉分析，探讨了中更新世以来的沉积演化和环境变迁特征。 新发现铜铅锌等矿化蚀变带2条，圈定了3处找矿靶区。对图幅内的生态地质进行了调查，重点对水土流失、土壤及植被特征等进行了调查，将本区土壤按矿质营养元素划分为五等，划分出富硒土壤远景区1处。 该项目取得的成果，为今后开展区域构造演化及解决关键地质问题提供重要线索和直接证据。

The Baiyin Aobao map sheet (L50E024024), Inner Mongolia, is located in a key segment of the Irtysh-Xilamulun suture zone. This study redefined the stratigraphic sequence, dividing it into 9 formation-level lithostratigraphic units and 8 Quaternary genetic type mapping units. An informal mapping unit for the Upper Permian Bayanhai Facies Volcanic-Sedimentary Rocks (P3bh) was established, and a LA-MC-ICP-MS zircon U-Pb age of 251.5±2.1 Ma was obtained from andesitic tuff. For the first time, the Upper Permian Linxi Formation was identified, which is mainly composed of semi-deep lacustrine and shore-shallow lacustrine sedimentary clastic rocks, and 4 layers of dark mudstone were newly mapped within the Linxi Formation. The Lower Triassic Laolongtou Formation was identified for the first time, which is mainly a suite of purplish-red clastic rocks intercalated with minor acid-intermediate volcanic clastic (lava) rocks; a LA-MC-ICP-MS zircon U-Pb age of 246.0±1.1 Ma was obtained from andesitic tuff. The Middle Jurassic Xinmin Formation was redefined, which is mainly composed of sedimentary clastic rocks intercalated with acidic volcanic rocks, with occasional coal seamlets. Calamites and silicified wood fossils were found in siltstone, and 2 sporopollen samples were collected from coarse sandstone, including 1 grain of Poaceae pollen and 3 grains of Pinus pollen. A LA-MC-ICP-MS zircon U-Pb age of 158.0±1.7 Ma was obtained from rhyolitic crystal-vitric tuff. The Upper Jurassic Manketou'ebo Formation was redefined, which is mainly a suite of continental acidic volcanic rocks and volcanic clastic rocks. A LA-MC-ICP-MS zircon U-Pb age of 152.7±1.7 Ma was obtained from rhyolitic crystal-vitric welded tuff. The Lower Cretaceous Manitu Formation was redefined, which is mainly a suite of continental neutral volcanic rocks, volcanic clastic rocks and sedimentary clastic rocks. A LA-MC-ICP-MS zircon U-Pb age of 135.4±1.2 Ma was obtained from andesite. The Lower Cretaceous Baiyingaolao Formation was redefined, which is a suite of continental acidic volcanic rock assemblages, with LA-MC-ICP-MS zircon U-Pb ages of 131.0±1.8 Ma obtained from rhyolite. The Lower Cretaceous Longjiang Formation and Guanghua Formation were identified for the first time, with a LA-MC-ICP-MS zircon U-Pb age of 129.6±1.7 Ma obtained from andesite in the Longjiang Formation. A suite of Early Cretaceous monzogranite pluton was identified in the Bayanbaolerri-Shengli Village area, with a LA-MC-ICP-MS zircon U-Pb age of 126.4±0.86 Ma. Using the three-fold mapping method of volcanic stratigraphy-lithology and lithofacies-volcanic structure, 2 volcanic basins, 5 volcanic edifices, 8 volcanic craters and 6 volcanic eruption cycles were divided in the Baiyin Aobao area. Multiple groups of optically stimulated luminescence (OSL) ages were obtained for Quaternary sediments: the Chifeng loess has an age of (>135.4±9.0) ka BP, belonging to the late Middle Pleistocene; the Wuerji Formation has an age of (>130.6±9.2~55.5±3.8) ka BP, belonging to the early-middle Late Pleistocene; the diluvial-alluvial deposits have an age of (5.5±0.3) ka BP, belonging to the late Middle Holocene. Through the analysis of grain size, magnetic susceptibility, carbonate content and sporopollen in Quaternary loose sediments, the sedimentary evolution and environmental changes since the Middle Pleistocene were discussed. Two Cu-Pb-Zn mineralized alteration zones were newly discovered, and 3 prospecting targets were delineated. An ecological geological survey was carried out in the map sheet, focusing on soil and water loss, soil and vegetation characteristics, etc. The soils in this area were divided into 5 grades based on mineral nutrient elements, and 1 selenium-rich soil prospecting area was delineated. The achievements obtained by this project provide important clues and direct evidence for future regional tectonic evolution research and solving key geological problems.