阴山地区前寒武纪变质岩石地层序列   总被引：1，自引：0，他引：1  

王楫  孙玉芳 《华北地质矿产杂志》1996,11(3):437-443

作者等从１９９０年开始，在研究阴山地区前寒武纪变质岩群年代构造格架过程中，采用“构造－地（岩）层－事件法”和变质岩构造解析的方法，对阴山地区前寒琥系重新进行了厘定，采用单颗粒锆石Ｕ－Ｐｂ，Ｓｍ－Ｎｄ等时线同位素测年方法对各岩群进行了测定，初步建立了阴山地区的前寒武纪变质岩群的年代构造格架，将阴山地区前寒武纪岩石地层序列划分为；中太古代兴和岩群，晚太古代集宁群／乌拉山岩群，色尔腾山群，古元古代层侵纪  相似文献   

银山矿床成矿作用时空特征及矿床成因讨论   总被引：4，自引：1，他引：4  

张德会 《矿床地质》1997,16(4):298-308

在对矿床地质地球化学详细研究的基础上，讨论了银山多金属矿床成矿作用的时空特征和矿床成因。研究表明，银山矿床的形成与燕山期第二阶段侵位的次火山岩具有密切的时空和物质组分的联系，然而，矿床与次火山岩都是深部隐估岩体岩浆分异的流体和熔体的产物，二者是同源但侵位有早晚的亲缘关系，矿床的成矿深化具有多期多阶段性。矿床分带上有多中心性、不对称性、叠加性和定性性。引起成矿物质沉淀的主要机制是注体的混合作用而不是  相似文献   

江西银山矿床矿物共生组合的重新厘定及其成因意义     

陈繁荣  肖振宇 《矿床地质》1997,16(4):309-317

江西银山多金属矿床发育南北不对称的矿化与蚀变分带，并以矿区南部的分带性较完整。研究表明，其矿区南部矿化分带的形成，是在成矿热液的缓慢演化过程中各种成矿元素依次沉淀的结果，其中石英或菱铁矿的梳状构造发育，线型蚀变较强，所形成的矿物自形程度高，杂质组分含量低；矿区北部九区含铜Ｚｎ－Ｐｂ矿化带有矿体系中有大量蒸汽加热酸性地下水的混入，这种酸性地下热水在矿床上部产生了大量高岭石化和重晶石化等酸性蚀变，并且  相似文献   

Sensitive High-Resolution Ion Microprobe U-Pb Zircon and ⁴⁰Ar-³⁹Ar Muscovite Ages of the Yinshan Deposit in the Northeast Jiangxi Province, South China     

Xiaofeng Li    Yasushi Watanabe    Jingwen Mao    Shengxiang Liu  Xiankui Yi 《Resource Geology》2007,57(3):325-337

The Yinshan deposit in the Jiangnan tectonic belt in South China consists of Pb‐Zn‐Ag and Cu‐Au ore bodies. This deposit contains approximately 83 Mt of the Cu‐Au ores at 0.52% Cu and 0.8 g/t Au, and 84 Mt of the Pb‐Zn‐Ag ores at 1.25% Pb, 1.02% Zn and 33.3 g/t Ag. It is hosted by low‐grade metamorphosed sedimentary rocks and mafic volcanic rocks of the lower Mesoproterozoic Shuangqiaoshan Group, and continental volcanic rocks of the Jurassic Erhuling Group and dacitic subvolcanic rocks. The ore bodies mainly consist of veinlets of sulfide minerals and sulfide‐disseminated rocks, which are divided into Cu‐Au and Pb‐Zn‐Ag ore bodies. The Cu‐Au ore bodies occur in the area close to a dacite porphyry stock (No. 3 stock), whereas Pb‐Zn‐Ag bodies occur in areas distal from the No. 3 stock. Muscovite is the main alteration mineral associated with the Cu‐Au ore bodies, and muscovite and chlorite are associated with the Pb‐Zn‐Ag ores. A zircon sensitive high‐resolution ion microprobe U‐Pb age from the No. 3 dacite stock suggests it was emplaced in Early Jurassic. Three ⁴⁰Ar‐³⁹Ar incremental‐heating mineral ages from muscovite, which are related to Cu‐Au and Pb‐Zn‐Ag mineralization, yielded 179–175 Ma. These muscovite ages indicate that Cu‐Au mineralization occurred at 178.2±1.4 Ma (2σ), and Pb‐Zn‐Ag mineralization at 175.4±1.2 Ma (2σ) and 175.3±1.1 Ma (2σ), which supports a restricted period for the mineralization. The Early Jurassic ages for the mineralization at Yinshan are similar to that of the porphyry Cu mineralization at Dexing in Jiangnan tectonic belt, and suggest that the polymetallic mineralization occurred in a regional transcompressional tectonic regime.  相似文献   

内蒙古阴山北部四子王旗土壤风蚀量的测试分析   总被引：10，自引：1，他引：10  

李晓丽  申向东  张雅静 《干旱区地理》2006,29(2):292-296

内蒙古阴山北部地区风蚀沙化十分严重,而风蚀量是判断土壤流失和荒漠化的重要指标。以阴山北部乌兰察布市四子王旗典型农牧交错带的耕地为试验地点,根据表层土壤多年的粒径变化,利用粒径对比法,对土壤风蚀量进行估算;并利用插钎法对一次强沙尘暴进行野外实测,推求土壤风蚀量;两种方法互相验证,近而对内蒙古阴山北部乌兰察布市的四子王旗土壤风蚀量进行较为准确测算。同时根据裸露耕地与未耕地(草地)的粒径对比分析,初步了解了该地区的由于传统耕作导致的土壤风蚀的程度,得出了耕地土壤风蚀的主要损失粒径为<0.05 mm的悬移质粉尘颗粒,该区域每年的平均风蚀模数达6 214.7 t/km2a,为干旱区耕地保护性耕作的研究提供基础理论依据。  相似文献   

Sedimentary record of Triassic intraplate extension in North China: evidence from the nonmarine NW Ordos Basin, Helan Shan and Zhuozi Shan   总被引：1，自引：0，他引：1  

Bradley D. Ritts  Andrew D. Hanson  Brian J. Darby  Lynde Nanson  Adrian Berry 《Tectonophysics》2004,386(3-4):177-202

The Helan Shan and Zhuozi Shan of the NW Ordos basin, China, contain thick (up to 4 km) sequences of nonmarine Triassic strata. These rocks represent a major intraplate sedimentary basin, the paleogeography, tectonic setting and provenance of which are poorly understood and controversial. Studies of the sedimentary geology of the basin, supported by new palinspastic reconstruction of younger deformation, demonstrate that the basin filled from three sides by fluvial, lacustrine-deltaic and alluvial fan depositional systems. The basin forms a westward-thickening wedge that reaches its maximum thickness along the western margin of the Helan Shan and thins to a relatively constant 600–800 m east of the Zhuozi Shan. The stratigraphy of the basin is strongly asymmetric; alluvial fan strata are restricted to the extreme western margin of the basin and interfinger with axial fluvial deposits low in the section and deep lacustrine facies high in the section. Much of the eastern part of the basin is dominated by west-flowing meandering river and deltaic systems. Large structures of Triassic age have not been identified in the Helan Shan or Zhuozi Shan, but small Triassic normal faults have been documented in the western and central Helan Shan. These characteristics most strongly support an extensional origin for the Triassic basin in NW Ordos. The basin is interpreted to have been a north-trending half graben, bound along its western margin by an east-dipping normal fault, presently concealed beneath Quaternary cover west of the Helan Shan. The eastern margin, now found in the Zhuozi Shan, has simple ramp-margin geometry. Driving mechanisms for this extension are not obvious due to limited documentation of Triassic structure throughout the region, but probably relate to far-field stresses from the Qinling or Jinsha active margins interacting with the stable Ordos block.  相似文献   

What drove late Mesozoic extension of the northern China–Mongolia tract?     

Qing-Ren Meng   《Tectonophysics》2003,369(3-4):155-174

The northern China–Mongolia tract exhibited a tectonic transition from contractional to extensional deformation in late Mesozoic time. Late Middle to early Late Jurassic crustal shortening is widely thought to have resulted from collision of an amalgamated North China–Mongolia block and the Siberian plate, but widespread late Late Jurassic–Early Cretaceous extension has not been satisfactorily explained by existing models. Some prominent features of the extensional tectonics of the northern China–Mongolia tract are: (1) Late Jurassic voluminous volcanism prior to Early Cretaceous large-magnitude rapid extension; (2) overlapping in time of contractional deformation in the Yinshan–Yanshan belt with development of extension-related basins in the interior of the northern China–Mongolia tract; and (3) widespread occurrence of alkali granitic plutonism, extensional basins and metamorphic core complexes in the Early Cretaceous. A new explanation is advanced in this study for this sequence of events. The collision of amalgamated North China–Mongolia with Siberia led to crustal overthickening of the northern China–Mongolia tract and formation of a high-standing plateau. Subsequent breakoff at depth of the north-dipping Mongol–Okhotsk oceanic slab is suggested as the main trigger for late Mesozoic lithospheric extension of that tract. Slab breakoff resulted in mantle lithospheric stretching of the adjacent northern China–Mongolia tract with subsequent ascent of hot asthenosphere and magmatic underplating at the base of the crust. Collectively, these phenomena triggered gravitational collapse of the previously thickened crust, leading to late Late Jurassic–Early Cretaceous crustal extension, and importantly, coeval contraction along the southern margin of the plateau in the Yinshan–Yanshan belt. The proposed model provides a framework for interpreting the spatial and temporal relationships of distinct processes and reconciling some seemingly contradictory phenomena, such as the synchronous extension of northerly terranes during major contraction in the neighboring Yanshan–Yinshan belt.  相似文献   

银山多金属矿床原生分带形成的矿物溶解度原因   总被引：3，自引：0，他引：3  

张德会  岑况 《矿物学报》1998,18(2):194-202

银山多金属矿床发育有序的原生金属分带,以3#和13#次火山岩的铜区作为成矿中心向上向外,由Cu－S－Au带、Cu－Pb-Zn带、Pb→Zn－Ag带→Pb-Ag带。使用多相多组分化学平衡计算程序（VCS）,模拟了成矿过程中主要成矿元素的溶解度,结合已有的实验研究成果,从环境物理化学条件改变对矿物溶解度影响的角度．探讨了原生金属分带形成的化学机理。研究不仅更深入地揭示了分带形成的物理化学因素,而且对进一步认识络合物在热液成矿中的意义具有重要的启示。  相似文献   

银山多金属矿床成矿分带的流体动力学计算模拟   总被引：8，自引：0，他引：8       下载免费PDF全文

张德会 《地球科学》1998,23(3):267-271

对江西银山矿床流体动力学热质输运数值模拟研究表明,矿区出露的火山岩墙尽管与矿化有密切的时空联系,但不能产生持久高强度的引起大范围矿化的能量场。模拟证实,矿区深８中存在隐伏岩体,其形态可能受银山背斜的控制,岩体顶面向南缓倾是矿化由早至晚由北东向南西迁移的主要原因。模拟结果合理解释了矿床分带的偏心规律。运用流体动力学计算模拟进行深部成岩预测,取得了预期效果。  相似文献   

江西银山铅锌矿床成矿流体特征   总被引：5，自引：0，他引：5       下载免费PDF全文

乐小横  张志辉 《地质找矿论丛》2001,16(1):28-31

银山铅锌矿床产于前震旦系地层中 ,容矿围岩主要为千枚岩 ,矿体呈脉状受构造裂隙控制。流体包裹体及同位素研究表明金属元素及硫主要来自上地幔 ,流体主要是岩浆水。矿床属中低温岩浆热液矿床 ,为燕山期成矿  相似文献