花岗岩石林(阿斯哈图)--一种新的地貌景观

首次在内蒙克什克腾旗增内的大兴安岭山脉的北大山上,发现世界罕见的花岗岩石林地貌景观。花岗岩石林是在特殊的内、外动力作用下形成的。花岗岩中的节理和裂隙是形成石林的构造基础;在古冰川、寒冻风化、风和水等外力作用下形成了石林。其形成和发育过程主要分为：冰川作用;寒冻风化、风和水等外力作用下形成了石林。其形成和发育过程主要分为：冰川作用;寒冻风化作用;风蚀作用和夷平作用４个阶段。花岗岩石林地貌是花岗岩地貌     

Genesis of the Late Mesozoic Great Xing’an Range Large Igneous Province in eastern central Asia: A Mongol–Okhotsk slab window model

The late Mesozoic Great Xing’an Range Large Igneous Province (XRLIP), with an area of >3 × 10⁵ km², is a prominent, enigmatic feature in eastern central Asia. The province is characterized by extensive within-plate magmatism, including a >4 km-thick sequence of volcanic rocks and voluminous plutons emplaced during an interval of ~40 million years from Late Jurassic through Early Cretaceous times (~150–110 Ma). The igneous activities are characterized by widespread adakitic rocks, alkalic basalts, and A-type granitoids with largely intraplate geochemical signatures, emplaced in a normal continental crustal setting. A Mongol–Okhotsk ridge subduction model is proposed for petrogenesis of the igneous rocks. Partial melting of young, hot, subducting oceanic slabs close to the ridge formed the adakitic rocks. A slab window that opened during ridge subduction triggered alkalic basaltic to A-type granitic and minor calc-alkaline magmas, as well as large-scale, metallogenic mineralization and subsequent basin formation.     

U–Pb zircon,geochemical and Sr–Nd–Hf isotopic constraints on age and origin of the intrusions from Wunugetushan porphyry deposit,Northeast China: implication for Triassic–Jurassic Cu–Mo mineralization in Mongolia–Erguna metallogenic belt

The Wunugetushan porphyry Cu–Mo deposit is located in northeastern China. The deposit lies within the Mongolia–Erguna metallogenic belt, which is associated with the evolution of the Mongol–Okhotsk Ocean. The multiple episodes of magmatism in the ore district, occurred from 206 to 173 Ma, can be divided into pre-mineralization stage (biotite granite), mineralization stage (monzogranitic porphyry and rhyolitic porphyry), and post-mineralization stage (andesitic porphyry). The biotite granite has (⁸⁷Sr/⁸⁶Sr)_i values of 0.704105–0.704706, ε_Nd(t) values of ?0.67 to ?0.07, and ε_Hf(t) values of ?0.4 to 2.8, yielding Hf two-stage model ages (T_DM2) 1250–1067 Ma, and Nd model ages of 1.04–0.96 Ga, indicating that the pre-mineralization magmas were generated by the remelting of Neoproterozoic juvenile crustal material. The monzogranitic porphyry has (⁸⁷Sr/⁸⁶Sr)_i values of 0.704707–0.706134, ε_Nd(t) values of 0.29–1.33, and ε_Hf(t) values of 1.0–2.9, yielding T_DM2 model ages of 1173–1047 Ma. The rhyolitic porphyry has (⁸⁷Sr/⁸⁶Sr)_i ratio of 0.702129, ε_Nd(t) value of ?0.21, and ε_Hf(t) values of ?0.5 to 7.1, T_DM2 model ages from 1269 to 782 Ma. These results show that the magmas of mineralization stage were generated by the partial melting of juvenile crust mixed with mantle-derived components. The andesitic porphyry has (⁸⁷Sr/⁸⁶Sr)_i ratio of 0.705284, ε_Nd(t) value of 0.82, and ε_Hf(t) values from 4.1 to 7.4, indicating that the post-mineralization magma source contained more mantle-derived material. The Mesozoic Cu–Mo deposits which genetically related to Mongol–Okhotsk Ocean were temporally distributed in Middle to Late Triassic (240–230 Ma), Early Jurassic (200–180 Ma), and Later Jurassic (160–150 Ma) period. The Middle Triassic to Early Jurassic Cu–Mo mineralization was dominated by Mongol–Okhotsk oceanic plate southeast-directed subducted beneath the Erguna massif. The Later Jurassic Cu–Mo mineralization was controlled by the continent–continent collision between Siberia plate and Erguna massif.     

Paleozoic northward drift of the North Tien Shan (Central Asia) as revealed by Ordovician and Carboniferous paleomagnetism

Three new Middle–Late Ordovician and two new Early Carboniferous paleomagnetic poles have been obtained from the North Tien Shan Zone (NTZ) of the Ural–Mongol belt in Kyrgyzstan and Kazakhstan. Paleolatitudes for the Carboniferous are unambiguously northerly and average 15.5°N, whereas the Ordovician paleolatitudes (6°, 9°, and 9°) are inferred to be southerly, given that a very large (180°) rotation of the NTZ would be necessary during the middle Paleozoic if the other polarity option was chosen. Thus, the NTZ drifted northward during much of the Paleozoic; east–west drift cannot be determined, as is well known, from paleomagnetic data. In addition, detailed thermal demagnetization analysis reveals two overprints, one of recent age and the other of Permian age, which is a time of strong deformation in the NTZ. The paleolatitude of the combined Permian overprint is 30.5+2°N. The paleolatitudes collectively track those predicted for the area by extrapolation from Baltica very well, but are different from those of Siberia for Ordovician times. This finding is compatible with Sengör and Natal'in's [Sengör, A.M.C., Natal'in, B.A., 1996. Paleotectonics of Asia: fragments of a synthesis. In: Yin A., Harrison, M. (Eds.), The Tectonic Evolution of Asia. Cambridge Univ. Press, Cambridge, pp. 486–640] model of tectonic evolution of the Ural–Mongol belt and disagrees with the models of other researchers. Declinations of the Ordovician and Early Carboniferous results range from northwesterly to northeasterly, and are clearly affected by local relative rotations, which seem characteristic for the entire NTZ, because the Permian overprint declinations also show such a spread. Apparently, the important latest Paleozoic–Triassic deformation involved shear zone-related rotations as well as folding and significant granitic intrusions.     

内蒙古阿拉善地区的第三系及其动物群

笔者依据丰富翔实的资料,论述了该区第三地层的分布,区划,地层划分沿革,岩性,岩相古地理特征及地质演化史;在地层方面,首次在内蒙古西部建立了比较完整的第三纪地层序列;命名和划分了中始新统乌兰乌珠尔组,上始新统查干布拉格组。下渐新统乌兰塔塔尔组,上渐新统,下中新统乌尔较组,上中新统呼和好来组和上新统昂冈浩特组等６个地层单元,补充界定了查干布拉格组并将其时代厘定为晚始新世;在动物群方面,发现和命名了中始     

1600-2000年地球主磁场的全球变化

根据汤普森（Thompson）地磁场模型和第 8代IGRF模型，计算了1600-2000年期间的偶极子磁场、非偶极子磁场、西向漂移和地磁功率谱等反映主磁场变化的主要参数，分析了各个参数的长期变化特征。主要结果是：400年来地磁场的偶极子磁矩持续减小，1800年以来磁心的位置快速离开地心向太平洋方向移动了291km；西向漂移有大约30年左右的周期；非偶极子磁场异常中，南大西洋正磁异常、非洲负磁异常和大洋洲负磁异常是1600年以来一直存在的 3个大型磁异常，东亚正磁异常和北美正磁异常是1700年后逐渐形成的，17世纪北太平洋地区存在强的正磁异常。     

白云石中Mn~(2+)及其占位的电子顺磁共振研究

本文用EPR法研究了白云鄂博矿床白云石中Mn~(2+)在Ca、Mg两个位置上的分配。通过比较白云石与菱镁矿中Mn~(2+)的精细结构线间的强度比,确定了几乎所有Mn~(2+)都处于Mg位置。其自旋哈密顿参数为:g=2.0022,A_∥=93.0×10~(-4)T,A_⊥=91.4×10~(-4)T,D=153.3×10~(-4)T。实验结果表明,白云石中Mn~(2+)的位置分配不取决于Mn~(2+)的浓度。离子半径和配位氧八面体畸变程度是控制位置分配的两个主要因素。     

地磁场的漂移运动和强度变化

在修正了Briggs提出的移动变形图案相关分析法基础上,对全球非偶极子磁场以及6个行星尺度磁异常区的漂移特性和强度变化进行了研究.结果表明,在1900-2000年期间,全球非偶极子磁场以0.15°/a的平均速度向西漂移,强度累计增长了29%;6个行星尺度异常区的西漂运动存在明显差异,其中漂移最快的是赤道附近的非洲异常,平均西漂速度为0.26°/a,其次是南半球的澳大利亚异常(0.23°/a),最慢的是欧亚异常(0.09°/a).除西漂外,大多数异常区还有较小的北向漂移.在1940-1955年期间北半球的欧亚、北美和北大西洋3个异常区以及赤道地区的非洲异常几乎同时由西漂或西南漂转为西北向漂移;紧接着,南半球的南大西洋和澳大利亚两个异常区的漂移特征也发生明显变化,主要是漂移明显减慢,而不是漂移方向的转折.在6个异常区中,澳大利亚、南大西洋、非洲和欧亚4个异常区的强度有明显增加,而北美和北大西洋两个异常区的强度则显示了减小的趋势.     

内蒙古白云鄂博群尖山组微古植物新发现

本文研究的微古植物,均发现于内蒙古白云鄂博群尖山组,共计10属33种,其中有3新种:Archaeodiscina baiyunensis sp.nov.,Lophosphaeridium favosumsp.nov.,Lophosphaeridium symbioense sp.nov.其组合特征以刺球藻群(Acanth-omorphida)的分子为主,球藻群(Sphaeromorphida)分子次之。在刺球藻群中以Baltisphaeridium属和Micrhystridium属的分子占绝对优势。微古植物个体一般为10—30μm。上述微古植物在我国云南昆明下寒武统以及欧洲、北美一些地区均有报道,充分显示出早寒武世特点。内蒙古白云鄂博群的时代,半个多世纪以来一直被认为属元古宙,本文的资料为重新判定白云鄂博群尖山组的时代,提供了新的古生物学依据。     

宁夏内蒙古交界地区的构造地震带及其地震活动性

根据活动断裂和近代地震震中分布，对宁夏内蒙古交界地区做了构造地震带的划分。研究了该区８个构造地震带１９７０年以来地震能量释放特征及地震时空分布特征。在指出该地区未来数年将处于地震活跃时段的基础上，对中强以上地震可能发生地点做了探讨，此项研究结果对地震预报有一定意义