To reveal the controlling mechanism of impact structure on the spatial distribution of radon and primordial natural radionuclides and provide basic data for planetary geological research, systematic field sampling and laboratory analyses were conducted at a certain impact crater in China. A high-purity germanium (HPGe) γ-ray spectrometer and scintillation-cell radon detector were adopted to measure the activity concentrations of 232 Th, 40 K and gaseous 222 Rn in granite, surface sediment and ambient air across 11 sampling sites covering crater core, crater rim and outer rim zones. The results indicated obvious spatial differentiation of target radionuclides following the sequence: granite > sediment and inner rim > outer rim. The measured specific activities of 40 K and 232 Th fell within the global natural background range, jointly governed by parent rock lithology, impact-induced rock fragmentation, weathering leaching as well as coupled topography and hydrological conditions. Radon concentration exhibited a distinct spatial pattern with high values concentrated in crater core and decreasing towards peripheral areas, and sediment was identified as the dominant radon reservoir within the study area. Radon concentrations in surface water remained low, indicating limited radiological risk under the measured conditions.. This study clarifies the spatial distribution patterns and controlling mechanisms of natural radioactivity for granite-hosted impact craters in frigid-temperate regions, supplying fundamental datasets and technical support for radiation risk evaluation and element cycling research of planetary impact geology.

A series of metamorphic core complexes, including the Xiaoqinling, Xiong'ershan, and Dabie Mountains, span from west to east within the Qinling-Dabie Orogen of Central China. Despite their similar formation timelines and tectonic trends, they exhibit distinct geochemical signatures and exhumation processes. In the Xiaoqinling region, magmatic source temperatures initially increase with depth from approximately 606 degrees C, reaching a peak around 847 degrees C, and then decrease to approximately 660 degrees C at greater depths, whereas in the Xiong'ershan area, they consistently decrease (811 -> 609 degrees C). The Dabie Mountains show consistent source temperatures (similar to 800 degrees C) across depths, suggesting their location above the 'kink' of Late Mesozoic Pacific subduction mantle wedge. Multi-method thermochronological analysis indicates that from 139 Ma to 85 Ma, the Xiaoqinling region cooled at 15.1 degrees C/Ma initially, followed by deceleration to 2.7 degrees C/Ma. Similarly, the Xiong'ershan and Dabie Mountains experienced two-stage exhumation processes, with cooling rates of 10.2 degrees C/Ma, 3.7 degrees C/Ma, and 20.3 degrees C/Ma, 3.2 degrees C/Ma, respectively. High-angle subduction and rollback of the ancient Pacific Plate during the Jurassic-Cretaceous transition facilitated the formation and rapid exposure of these metamorphic core complexes. Subsequent Pacific subduction reorientation during the Late Cretaceous reduced regional extension and thereby decreased the uplift and exhumation rates of these complexes.

The geologic cross-section is an indispensable complement to the geologic map and is the model that represents the underground extension of the materials of the structures. It still lacks an automatic way to adapt to digital transformation. A novel method is proposed to improve the efficiency and accuracy of geologic cross-section construction by spatial data projection. The method has three main steps as follows: 1) Calculation. All key components on the cross-section, including topographic profile and structural data, are automatically generated through a relational database table. 2) Spatial coordinates projection. A cross-section in a free direction comes from the projection of a three dimensional data source. The geometric parameters of the geologic cross-section are obtained through the dimensionality reduction projection of the point coordinates. 3) Data extension. The extension of geologic structures in the subsurface and denuded areas and the spatial relationship between contact lines and topographic profiles are discussed. Four case studies, including Digital Contour Map, Remote Sensing, Global Navigator Satellite System (GNSS), and Laser rangefinder, successfully demonstrate that the proposed method is a simple, flexible, fast, precise, and visual process that can generate digital cross-sections automatically and efficiently through multi-source topographic and geologic data.

Analysis of tectonothermal history of the Yanchang Formation in the western Weibei Uplift and in the northwestern Weihe Basin can reconstruct the cooling history of the southwest most remained Upper Triassic source rock of the North China Plate. Apatite fission-track (AFT) and (U-Th-Sm)/He (AHe) analysis were used to recover the cooling and uplift history of the Upper Triassic here. Ten sandstones from the Middle-Upper Triassic strata yield AFT ages between 179.8 ± 7.4 and 127.6 ± 8.1 Ma. AHe ages of two sandstones have the value of 37.7 ± 2.3–131.1 ± 8.1 and 45.7 ± 2.8–83.5 ± 5.2 Ma. Time-temperature modeling results showed that tectonothermal history of the Yanchang Formation was initially different in time-space relationships but then became almost identical through time followed by different cooling rate. Modeling results of the Triassic strata in the Qianyang area and the Yaojiagou area revealed three different uplift-cooling stages commencing in the Late Jurassic at ∼165 Ma and in Early Cretaceous at ∼110 Ma, respectively, both followed by first similar cooling histories to the Early Miocene at ∼20–23 Ma and then different since the Late Miocene. Uplift-cooling rate since the Late Miocene at ∼8 Ma were different between the Western Weibei Uplift and the Northwestern Weihe Basin. The timing, cooling-uplift rates of the Yaojiagou area, which was mainly controlled by movements related to the Liupanshan Mountains, the Qinling Orogens and the Weibei Uplift, had the earliest onset of uplift-cooling for the Upper Triassic series compared to other regions within the Weibei Uplift. Cooling paths for the Upper Triassic series became uniform regionally in the Early Cretaceous marking a key time for the tectonothermal evolutionary history of Upper Triassic series in the southwestern North China Plate.

[目的]通过分析辽宁省宽甸县牛毛坞镇联办硼矿矿产资源开发后的地质环境问题,为矿山生态环境治理修复提供意见.[方法]以牛毛乌镇矿区为研究对象,剖析矿区的气候与土壤、地形地貌、水文地质条件后采用截流沟工程、生物技术和化学技术与生物工程进行矿山地质环境的防治.[结果]目前矿山的地质环境问题,已得到相应改善.[结论]当前社会由于过度开矿而引发的地质灾害,严重阻碍了部分地区生态环境和谐发展.因此,要充分关注矿山的地质和生态环境问题,及时制定相应的防治措施和修复计划.

Jiurui ore concentration area is an important part of the middle and lower reaches of Yangtze River metallogenic belt.The study area of Pengshan polymetallic ore field is located in the south of Jiurui ore concentration area, which is rich in mineral resources, but the structural pattern is controversial.In this paper, based on the comprehensive analysis of geological and geophysical characteristics, it is proposed that Pengshan ore field is controlled by the structure of magmatic core complex, and the core of Pengshan magmatic core complex upheaval-detachment structure is composed of elliptical granitoid intrusive rock mass, which was a hidden uplift in the middle Yanshanian period and was shaped in the late Yanshanian period.The peripheral shallow sedimentary rocks are in a domed zonal distribution around the magmatic core complex.The peripheral fault zone tends to deviate from the direction of magmatic core complex and shows a shovel distribution, indicating the detachment structure characteristics.The halo type ore belt types of Pengshan ore field, with the concealed granitic body in the core as the center, the change of high temperature ore to low temperature ore occurs in the surrounding, such as arsenite（arsenopyrite）-tin ore-lead-zinc ore-fluorite ore-barite ore and so on, which is also the result of mineral enrichment along the multi-level detachment faults, and the mineralization occurs in the inner and outer contact zone of the magmatic core complex, forming skarn type, porphyry type and hydrothermal vein type Sn-Pb-Zn polymetallic deposits in the structural relaxation stage.

野外实习是培养合格地质人才的重要环节和专业特色,对培养学生兴趣、巩固专业知识、提高实践能力等有着不可替代的作用.然而传统野外地质教学实习中存在效率低、成本高、互动性和共享性差等问题,虚拟仿真教学很好地弥补了此缺陷.通过以汉中梁山野外地质实习基地为例,介绍了长安大学地质学类专业野外地质实习的发展现状,实习目的和任务,分析了传统野外地质实习存在的问题,探讨了汉中梁山野外地质实习虚拟仿真教学平台建设的思路和拟解决的关键问题.

华北克拉通古元古代的构造格局是学术界关注的焦点之一,位于华北克拉通南缘的穆册二长岩体为该研究提供了新的证据.穆册岩体主体为黑云角闪二长岩,边部见二长斑岩,并被同期二长花岗岩脉侵入.二长岩的LA-ICP-MS锆石U-Pb定年为2172±8 Ma(MSWD=0.58,n=17)和2186±7 Ma(MSWD=0.60,n=19),二长花岗岩年龄为2174±8 Ma(MSWD=0.45,n=19),显示该二长岩体形成于古元古代.穆册二长岩不仅具有造山后地球化学特征,还具有典型的岛弧岩浆岩的地球化学特征.综合分析,穆册二长岩可能在古元古代经历了岛弧和裂谷两种环境的共同影响.

范家山铜金矿位于西秦岭北成矿亚带,温泉复式花岗岩-天水斑岩-夕卡岩钼铜金矿带的核心位置.矿床地质特征表明:范家山铜金矿体主要受岩体与围岩接触带以及岩体附近的断裂破碎带的控制,以金铜矿化为主,围岩蚀变为夕卡岩化、角岩化及硅化、绢英岩化等.范家山铜金矿床主矿脉包裹体温度、盐度及H-O同位素研究显示,主成矿流体的盐度(S)为2.0％～11.0％(w(NaCl)eq),均一温度为120～345℃,主要集中在150～280℃范围,具有中温和中低盐度的特征,为岩浆水和大气降水的混合.成矿花岗斑岩锆石U-Pb年龄为(248.3±1.9) Ma(MSWD=0.67,N=9),表明成矿活动发生在印支早期.结合区域构造背景,范家山铜金矿为印支期早期陆陆碰撞导致地壳加厚背景下的夕卡岩型矿床,深部具有斑岩型成矿的潜力.

Gold deposits are closely related to accretionary processes. Gold mineralization in eastern China, however, is usually > 100 Ma younger than associated collisional orogeny and partly controlled by extensional tectonics. Being controlled by interbedded detachment faults, the Luyuangou hydrothermal deposit is a typical mineralization under extensional tectonic. We present mineral deposit geology, tectonic geology, LA‐ICP MS zircon U–Pb age data, and Sr‐Nd‐Hf isotopic data for the Luyuangou ore vein and porphyritic dyke, with the aim of elucidating the metallogenesis. The morphological features and ages of zircons from the Luyuangou auriferous lode are similar to the anatectic zircons from migmatite within the Qinling Group (a metamorphic complex unit) of the North Qinling Terrane, indicating that the North Qinling Terrane may be one of the provenances. Although the major age peak of 453 ± 13 Ma (MSWD = 3.3, N = 12) cannot constrain the exact metallogenic timing, the data imply a possible link between the Luyuangou metallization and the North Qinling Terrane. Meanwhile, the weighted‐mean age of post‐ore porphyritic dyke postdates the Luyuangou gold mineralization at 121.1 ± 1.5 Ma (MSWD = 0.21, N = 14). The Sr‐Nd‐Hf isotopes of the Luyuangou auriferous lodes and post‐ore porphyritic dyke exhibit prominent differences from those of the Taihua Group and Xiong'er Group and are similar to those of the Qinling Group, implying that the Qinling Group is likely the main ore‐forming provenance of the Luyuangou gold deposit. The S‐Pb isotopes of the main mineralization stage of the Luyuangou gold deposit indicate a distinct deep‐seated source. According to comprehensive analysis, it is proposed that, during the early Mesozoic, the large‐scale continental collision between the Yangtze and the North China Craton involved the underthrusting of the North Qinling Terrane beneath the North China Craton that led to intracontinental folding, thrusting, and thickening without inducing extensive mineralization or magmatic activity. During the late Mesozoic, the subduction of the Pacific Plate induced the instability of the thickened continental crust and the development of the regional extensional structures, large‐scale crust–mantle magmatism as well as deep‐seated or mantle‐derived fluids dissolving materials from the Qinling Group that precipitated at the interbedded detachment faults.

The relationship between collision orogeny and post‐orogeny tectonism remains to be a weakness of the present orogenic belt research. An E—W‐trending ductile shear zone exposed along the Bogda Mountain of the Eastern Tianshan Orogenic Belt (ETOB) has spatiotemporal correlation with the Kelameili ophiolite belt and offers important evidence for research on the evolution of the ETOB. These ductile shear belts exposed in the eastern Sa'erqiaoke display that the low greenschist facies metamorphism was followed by north‐eastward thrusting and sinistral strike‐slip shearing. LA‐ICP MS zircon U–Pb ages of the mylonitic quartz schist in Sa'erqiaoke structure section range from 226 to 1458 Ma, four old zircons with ages of 832.2, 1029.2, 1240.5, and 1458.2 Ma possess round‐shaped grains and core–mantle texture, which suggest that its protolith has a detritic and metamorphic origin. The major age peak ranges from 443.3 to 466.8 Ma, with weighted age of 452.9 ± 5.4 (MSWD = 0.62, N = 13), corresponding to the early Palaeozoic Harlic island arc magmatism. Two young metamorphic zircons with ages of 247.2 and 226 Ma could represent the time of ductile shearing, which are consistent with the final termination of the ETOB. Two weighted ages of 303.8 ± 3.4 (MSWD = 0.12, N = 16) and 305.2 ± 2.4 (MSWD = 0.46, N = 32) from Nawakuduke mylonitic belts are coeval with post‐collision A‐type granite of the Kelameili suture, which suggest that the ductile shearing should be later than the closure of the Kelameili Ocean. Based on the synthesis of voluminous evidences, we propose that the Kelameili Ocean, as part of the paleo‐Tianshan Ocean, obliquely subducted beneath the Junggar plate, bringing about the Bogda subduction‐torn‐type rift during the Carboniferous period. Although the final closure of the Kelameili Ocean has ended at late Carboniferous, the subsequent continental collision and large‐scale ductile shearing lasted until late Triassic.

A diversity of morphological structures of Au-bearing pyrites exists during the main metallogenic stage.These structures include the corrosion metasomatic,proliferation,directed modification,dissemination and veined types.The phenomenon that multiple morphological structures exist in sole metallogenic epoch indicates that the morphological structural classification and in-situ pyrite testing are desperately needed.The present study conducted research on these two topics based on macroscopic examinations.The results show that gold-bearing pyrites were the products of the pre-enrichment,the main-metallogenic and the postmetallogenic stages.All three periods embodied depositional characteristics that the pyrites were rich in S and poor in Fe,and rich in Ni and deficient in Co.In addition,post-metallogenic stage embodied the metamorphism superposition characteristics that the pyrites were rich in Fe and deficient in S.It is believed by a comprehensive study that the morphological,textural and constitutional typomorphism of pyrites indicate different origin and complex evolutionary process;these typomorphic characteristics can be significant in genesis discrimination,exploration and prospecting of gold deposits.

石灰窑花岗岩位于卡拉麦里蛇绿岩带的最东段,岩性为中粗粒钾长花岗岩.岩体具有高硅(74.13％～75.76％)、高钾(4.26％～5.59％)、低镁铁[w(MgO+Fe2O3+TiO2)介于1.55％～3.37％之间]、高A/CNK(0.99～1.12)特征,刚玉标准分子略高(0.003％～1.46％),属高钾钙碱性过铝质S型花岗岩.岩体富钾(K2O/Na2O值介于1.12～2.06之间),高Rb、Cs,低CaO/Na2O值(0.18～0.34之间),显示源区主体为富云母的变泥质岩区.岩石明显富集Rb、Th、U、K和Pb等大离子亲石元素,强烈亏损Ba、Sr、P、Ti、Eu等元素,并具有弱的Nb亏损,具有俯冲相关的火山弧和后碰撞伸展花岗岩类的地球化学特征.岩体侵位于下石炭统山梁砾石组地层,南界被蛇绿混杂岩的边界断裂切割,岩体LA-ICP-MS锆石U-Pb年龄(282.9±3.6)Ma应代表了卡拉麦里蛇绿混杂岩带东段的闭合年龄.结合区域构造背景分析,石灰窑花岗岩形成于卡拉麦里俯冲碰撞向碰撞后伸展的过渡阶段,是局部减压和地幔热流异常导致上地壳物质发生部分熔融的产物.

马元铅锌矿床是中国近年来在扬子板块北缘南大巴山陆内造山带中发现的大型铅锌矿床.对矿田构造的研究发现,成矿作用受震旦系灯影组白云岩地层层间破碎带的控制.破碎带中见大量紧闭褶皱转折端角砾,下盘附近发育层间剪切滑移断层带,显示控矿构造为低角度逆冲推覆过程中形成的断层褶皱和与之相关的角砾岩.矿质充填在破碎带白云岩角砾间的空隙中,矿石的晶洞-梳状构造发育,未见后期破坏,表明矿床形成于构造定型期.对成矿晚期热液沥青进行Re-Os同位素年龄测试,获得(126±8)Ma的等时线年龄,结合区域构造背景,认为该矿床形成于中晚侏罗世.控矿构造角砾岩为低角度逆冲推覆构造作用的产物.

1∶25万三道岭幅区调项目在巴里坤萨尔乔克东侧冲沟原中泥盆统头苏泉组地层中,发现一套中级变质岩系,根据岩石组合、变质变形等方面的对比,研究认为该套地层与头苏泉组存在较大差异,因此需要重新厘定.为了准确确定该套地层的岩石单元归属,在萨尔乔克东侧冲沟的剖面上,先后两次采集同位素年龄样品D1710TW1和D1710TW2,从石英片岩中挑选51颗锆石进行了LA—ICP—MS锆石U—Pb定年研究.研究认为该组锆石具有多来源、多期次的特征;代表地层形成时代的锆石U—Pb年龄为450.3士4.3Ma,该套地层的岩性、岩相和变质程度,在区域上可以和乌列盖组对比,因此本文将其厘定为上奥陶统乌列盖组;其中的碎屑锆石数据表明该地存在前寒武纪基底.

苏吉山辉长岩体位于博格达碰撞造山带东段，卡拉麦里蛇绿混杂岩带西南侧，出露面积约1.8 km2，岩性为石英角闪辉长岩。苏吉山辉长岩体富含普通角闪石（20%）和磁铁矿物，表明原生岩浆富水、高氧逸度特征，岩石化学组成属于拉斑玄武岩系列，岩石弱富集大离子亲石元素Cs、Rb、Ba、Th、U，显著亏损Nb、Ta、Zr、Hf 和弱亏损Ti，显示源区为受俯冲流体交代改造的岩石圈地幔，应是洋壳俯冲的产物。苏吉山辉长岩体锆石U-Pb年龄为308.1±3.3Ma，早于卡拉麦里混杂岩带内碱性花岗岩侵位，介于博格达裂谷活动期，是裂谷作用由全面伸展向局限伸展转换的标志。苏吉山辉长岩空间上位于古亚洲洋板块沿卡拉麦里蛇绿混杂岩带向准噶尔板块斜向俯冲的前进方向，时间上介于博格达裂谷活动期，地球化学上显示洋壳俯冲的特征，各种事实表明，古亚洲洋沿卡拉麦里碰撞带向准噶尔板块斜向俯冲作用形成撕裂型博格达裂谷，博格达裂谷由伸展机制向伸展-碰撞过渡机制的应力调整导致了苏吉山辉长岩体的侵位。

为探讨陆院沟矿区斑岩在成矿中的作用,依据质量平衡方程和等比线法,对斑岩株蚀变围岩的元素迁移规律进行定量分析.结果表明,紧邻侵入体的强蚀变围岩中主量元素相对迁移率为-168.2％ ～71.9％,矿化元素相对迁移率为23.9％ ～611.7％,远离侵入体的弱蚀变围岩中主量元素相对迁移率为-53.1％ ～42.5％,矿化元素相对迁移率为-52.5％～43.9％.SiO2迁出率随蚀变增强而升高;K2O质量分数随蚀变增强先降后升,MgO和CaO亦如此;Na2O随蚀变增强先升高后期迁出殆尽,TiO2、FeO、Fe2O3、MnO和P2O5等与之规律相似.正长斑岩侵位早期蚀交流体以富气、少水、高能为特征,蚀变范围广,强度低,以绿泥石化为主;侵位中后期形成富水、赋矿的流体,蚀变范围小、强度大,以钾化、绿泥石化和矿化为主.陆院沟矿区内斑岩株是花山岩基的延伸,是深部能量、流体和矿质释放的通道.

Based on 1/200 000 geochemical exploration data of northern Chifeng area and the theory of geochemical blocks,the authors have studied the characteristics of Pb geochemical block and Pb mineral resources, and identified two Pb geochemical blocks and six relatively small geochemical anomaly areas. Through analyzing the controlling factors of Pb geochemical blocks, the authors suggest that the contacting zone or outer contacting zone of Yanshanian intermediate-felsic intrusive rocks are the favorable locations for the blocks, and the Permian Huanggangliang and Dashizhai Formation, Jurassic Manitu and Xinmin Formation, and Upper Silurian Xingshuwa Formation are considered as the main strata for those blocks. The size of blocks is obviously controlled by NW-and NE-striking faults. By taking 1 000 m as the criterion, the total predicted mineral resource of Pb is 18.935 3 million tons in the study area. The study area was subdivided into nine Pb prospect areas, and three of them (No.1113-1, No.1411-1 and No.3111-1) are first-order areas.