南海东北部陆缘区新近纪早期反转构造特征及其动力学意义

通过深入分析九七三项目所获取的高分辨率多道地震剖面,结合区域钻井资料,探讨了新生代以来南海东北部陆缘所历经的新生代早期张裂、中新世晚期阶段性挤压及上新世以来的稳定热沉降等复杂构造运动;张裂背景下的南海东北部陆缘在中新统中部、下部出现的背斜、逆断层等典型压性反转构造,凸现了南海东北部陆缘在晚中新世发生的阶段性挤压构造运动;分析表明,此构造活动是东沙运动在台西南海域的表现,其动力来源同菲律宾海板块的北西向运动有关。     

The Central Scandinavian Dolerite Group—Protracted hotspot activity or back-arc magmatism?: Constraints from U–Pb baddeleyite geochronology and Hf isotopic data

The Central Scandinavian Dolerite Group (CSDG) occurs in five separate complexes in central Sweden and SW Finland. U–Pb baddeleyite ages of dolerite dikes and sills fall into three age intervals: 1264–1271 (the Dalarna complex), 1256–1259 (the Västerbotten-Ulvö-Satakunta complexes) and 1247 Ma (the Jämtland complex). Timing and spatial distribution of CSDG are unlike expressions of the voluminous and short-lived magmatism which characterises plume-associated large igneous provinces (LIPs). Protracted mafic magmatism in association with mantle plume tail (hotspot) activity beneath the Fennoscandian lithosphere or discrete events of extension behind an active margin (subduction) are considered more plausible tectonic settings. Both settings are consistent with timing, relative magma volumes between complexes and vertical ascent of individual magma pulses through the crust, as inferred from seismic sections [Korja, A., Heikkinen, P., Aaro, S., 2001. Crustal structure of the northern Baltic Sea palaeorift. Teconophysics 331, 341–358]. In the hotspot model, the lack of a linear track of intrusions can be explained by an almost stationary position of Fennoscandia relative to the hotspot, in agreement with palaeomagnetic data [Elming, S.-Å., Mattsson, H., 2001. Post Jotnian basic intrusion in the Fennoscandian Shield, and the break up of Baltica from Laurentia: a palaeomagnetic and AMS study. Precambrian Res. 108, 215–236]). Together with geological evidence, dolerite sill complexes and dike swarms in Labrador (Canada), S Greenland and central Scandinavia in the range 1234–1284 Ma are best explained by long-lived subduction along a continuous Laurentia-Baltica margin preceding Rodinia formation. There is no support for the hypothesis that CSDG was fed by magma derived from a distal mantle plume located between Baltica and Greenland and, hence, for rifting between the cratons at 1.26 Ga.The epsilon-Hf in various members of the CSDG varies between 4.7 and 10.3, which are overall higher than both older and younger Mesoproterozoic mafic intrusions in central Fennoscandia. Magma generated from a hotspot mantle source that was mixed to highly variable degrees with an enriched subcontinental lithospheric mantle could account for the wide range in Hf isotope composition. In the course of Hf isotope development work during this project we have analysed four fragments of the Geostandard 91500 reference zircon and after evaluating the existing ICPMS and TIMS data we calculate a mean ¹⁷⁶Hf/¹⁷⁷Hf value of 0.282303 ± 0.000003 (2σ).     

大地构造和海陆起源的内波假说（Ⅰ）──关于板块学说的若干问题及其思考

随着资料的积累，不断发现与板块假说相矛盾的事实：地震层析没有发现地幔对流的证据，却发现大陆克拉通具有４００ｋｍ深的“壳根”；海洋地质调查发现了一系列否定板块假说的重要证据，尤其是大西洋中多处发现古岩石，使海底扩张模型受到严重挑战；跨越扩张脊的一系列测量结果实际上否定了扩张假说。此外，作为学说重要支柱的地磁资料的可靠性受到怀疑，板块消减过程中洋底沉积层堆积被否定，大陆碰撞模式与陆上地质资料的不符，动力机制不明，板块模式不适于解释复杂的大陆地质而难以登陆等事实，已令板块构造理论陷入了深刻的危机之中。根据煤和蒸发岩的地史分布等资料，说明一个海陆相对固定的大地构造模型更符合实际。通过对大地构造假说发展史的分析和研究，并借鉴天文学中太阳系的发现史，认为新假说的建立必须从确凿的地质现象，而非多解性的资料和推断出发。由此提出大地构造和海陆起源的内波假说。     

辽西医巫闾山地区中生代两期韧性变形的研究

医巫闾山地区的韧性剪切构造是中生代两期韧性变形作用的产物。早期韧性变形中a线理发育,线理走向和糜棱面理走向基本一致,线理在xy面上的侧伏角绝大多数<30°;该期韧性变形是以左行走滑运动为主。晚期韧性变形中a线理发育,线理倾伏向和糜棱岩中糜棱面理倾向相近,线理在xy面上侧伏角主要在45°～90°之间;该期韧性变形是伸展作用的产物。医巫闾山中生代两期韧性剪切变形作用表明,在侏罗纪至早白垩世期间辽西地区不仅发生了强烈挤压推覆作用和伸展作用,也发生了大规模左行走滑作用。该韧性变形作用的发现对进一步研究辽西中生代的构造演化序列、期次和构造格架转换等问题有重要意义。     

赣杭构造带中生代红色碎屑沉积盆地的形成和演化

本文是在继讨论赣杭构造带中生代火山盆地的形成和演化之后,再对赣杭构造带中生代红色碎屑沉积盆地（简称赣杭带红盆）的形成和演化作一探讨。涉及的内容主要有：赣杭构造带中生代红盆结构及演化时代;从晚侏罗世末到整个白垩纪各期主要构造运动及与红盆演化的关系;箕状盆地的几个主要特征;红盆演化的动力学背景;红盆所对应的深部构造以及深断裂活动和盆地演化的实际含义等     

Shape and amount of the Quaternary uplift of the western Rhenish shield and the Ardennes (western Europe)

A good evaluation of the Quaternary uplift of the Rhenish shield is a key element for the understanding of the Cenozoic geodynamics of the western European platform in front of the alpine arc. Previous maps of the massif uplift relied on fluvial incision data since the time of the rivers' Younger Main Terrace to infer a maximum post-0.73 Ma uplift of ~ 290 m in the SE Eifel. Here, we propose a new interpretation of the incision data of the intra-massif streams, where anomalies in the terrace profiles would result from knickpoint retreat in the tributaries of the main rivers rather than from tectonic deformation. We also use additional geomorphological data referring to (1) deformed Tertiary planation surfaces, (2) the history of stream piracy that severely affected the Meuse basin in the last 1 Ma, and (3) incision data outside the Rhenish shield. A new map of the post-0.73 Ma uplift of the Rhenish shield is drawn on the basis of this enlarged dataset. It reduces the maximum amount of tectonic uplift in the SE Eifel to ~ 140 m and modifies the general shape of the uplift, namely straightening its E–W profile. It is also suggested that an uplift wave migrated across the massif, starting from its southern margin in the early Pleistocene and currently showing the highest intensity of uplift in the northern Ardennes and Eifel. These features seem to favour an uplift mechanism chiefly related to lithospheric folding and minimize the impact on the topography of a more local Eifel plume.     

塔里木盆地多期改造-晚期定型复合构造与油气战略选区

受关键构造变革期制约,叠合盆地具有分期差异变形特征。从变形角度分析,塔里木盆地可以追溯出5期主要的构造改造作用,即加里东中期、加里东晚期-海西早期、海西晚期、印支-燕山期和喜马拉雅期,并影响塔里木盆地的发展演化历史。通过对塔北、塔中和库车已知油气聚集区解剖表明:古生代多期改造形成的断裂、褶皱、隆升、剥蚀和岩溶作用,对台盆区巨型海相碳酸盐岩古岩溶油气藏的形成具有重要的控制作用;中、新生代多期改造过程,对前陆褶皱-冲断带大规模油气聚集成藏具有重要的控制作用;这些已知油气聚集区带都是在喜马拉雅晚期最终定型的,总体构成多期改造-晚期定型复合构造油气聚集模式。综合分析了塔里木新区分期差异构造变形特征,在此基础上,依据叠合盆地多期改造-晚期定型构造模式,对塔里木新区进行了区块评价和油气战略选区,认为巴楚隆起、麦盖提斜坡和西昆仑山前褶皱-冲断带是近期油气勘探突破的首选地区,塔东地区、塘古巴斯坳陷和阿瓦提断陷具有良好的油气勘探前景。     

黔中—渝南沉积型铝土矿区域成矿模式及找矿模型

黔中—渝南沉积型铝土矿的区域成矿模式概括如下:志留纪末的广西运动和泥盆纪末的紫云运动等,可能都是在峨眉地幔柱演化的壳幔相互作用阶段,因地幔柱向地壳大量输送物质和辐射能量,从而引发的地壳升降运动,在此期间,全区大面积抬升,形成长期隆起区;泥盆纪末准平原化;早石炭世岩关期气候湿热,暴露地表的早古生代岩石全面红土化、钙红土化,形成的含三水铝石红土风化壳物质,为沉积型铝土矿提供了物源。修文及息烽—遵义沉积区,于早石炭世大塘期早—中期沉积了铝土矿含矿岩系—九架炉组。绥阳—正安—道真沉积区,在晚石炭世的黄龙组石灰岩沉积并钙红土化之后,于马平期沉积了铝土矿含矿岩系的大竹园组。3个沉积区的铝土矿含矿岩系,都是在以陆相为主的环境中沉积形成的。在成岩阶段,铝土矿中的三水铝石逐渐变质为硬水铝石。由于各沉积区形成含三水铝石红土风化壳的母岩不同,由此沉积而成的铝土矿及其含矿岩系,在化学成分和矿物成分上也就有所差异。     

赞比亚西北省铜-钴矿地质及找矿潜力

[摘 要]赞比亚位于著名的中非新元古代沉积型铜（-钴）矿带上,铜带省和西北省是该国最主要的铜-钴矿集中分布区;相对于找矿程度已经很高的铜带省,西北省成矿地质条件优越,且地质工作程度较低,因此拥有巨大的找矿潜力,已成为该国找矿突破的重点区域。目前西北省主要著名的矿山/矿床有3个：坎桑希、卢穆瓦纳、卡伦比拉。这些铜-钴-金-铀-镍矿床的含矿地层、矿化特征与铜带省传统经典的沉积型铜-钴矿既有相似性,又明显具有差别。本文通过对西北省区域地质和已发现矿床地质特征的介绍,对该省的找矿潜力进行初步分析。