后撤式逆冲推覆断层成因机制及物理模拟——以准噶尔盆地西北缘克-百断裂带为例

位于准噶尔盆地西北缘中段的克-百断裂带,晚二叠世以来发育了一系列后撤式逆冲断层。长期以来,关于克-百断裂带高角度逆冲断层的成因机制一直处于争论当中,后撤式逆冲断层的物理模拟在国内尚未见文献报道。论文通过地震解释研究了克-百断裂带的构造变形特征及其演化阶段;应用断层"活动性系数"理论,半定量地描述了挤压条件下断层"活动性系数"、摩擦系数与断层倾角之间的关系,证明了挤压条件下也能形成高角度逆断层;结合"造山楔"理论解释了后撤式逆冲断层的成因机制。研究认为,克-百断裂带后撤式逆冲断层是印支期、燕山期持续挤压和扎伊尔山隆升效应综合作用的产物:挤压过程中发生"泊松效应",随着断层倾角增大,断层面上的正压力迅速增大、"活动性系数"降低,当倾角增大到一个临界值后断层停止活动,形成高角度的逆断层;同时扎伊尔山隆升造成挤压应力上移,为断层的后撤奠定了基础。最后利用砂箱物理实验模拟了克-百断裂带后撤式逆冲断层的形成过程。     

基于RAGA的PPC模型在化探异常分析中的应用——以凤太矿集区为例

化探数据处理的核心内容是地球化学背景与地球化学异常的合理区分,找矿信息提取将直接影响到成矿预测的结果.文章采用基于RAGA的PPC模型对凤太矿集区1:5万水系沉积物化探数据进行处理,初步探讨了投影寻踪聚类方法在地球化学异常识别与元素共生组合方面的应用,以及投影方向值所代表的地质意义.结果表明,PPC模型的化探异常识别效...     

中酸性隐爆角砾岩型金属矿床稀土元素地球化学特征

与火山、次火山隐爆作用有关的中酸性隐爆角砾岩型矿床是一种重要的矿床类型.中酸性隐爆角砾岩型金、银-金、铀、钨-钼-铜-铅-锌典型矿床的矿石、蚀变围岩稀土元素研究表明,不同矿种的矿床稀土元素地球化学具有极强的相似性和弱差异性.矿床稀土元素总量w(REE)=69.7×10-6～245.27×10-6,单个矿床稀土元素总量变...     

The Solid-liquid Transformation of Low-grade Solid Potash Deposit in Dalangtan Basin and the Simplification of the Liquid Phase System

正We studied the solid-liquid transformation of low-grade solid potash deposit in Dalangtan Basin and simplified the liquid phase system.We did experiments to optimize conditions of the solid-liquid transformation.The Suitable     

东天山喀尔里克山北坡淖毛湖盆地土壤粒度分布特征及成因

对东天山喀尔里克山北坡-淖毛湖盆地不同类型土壤的粒度进行分析.结果表明:研究区土壤主要由粉粒和砂粒组成,从喀尔里克山北坡、中部地区到淖毛湖盆地,土壤粒度平均值逐渐变大,颗粒分选性差,偏度多属极正偏或正偏,峰态集中在宽、中等和窄3个等级,表明其成土母质较粗、来源相对复杂.土壤的粒度参数Mz、σ、SK和KG值很好地表征了不同土地类型和植被类型及盖度对土壤粒度特征的影响.土壤粒度分维值呈现出随海拔降低逐渐减小的趋势,并且分维值与粘粒含量呈正相关关系.喀尔里克山北坡土壤中粘粒的含量高于中部地区和淖毛湖盆地的土壤,反映出不同地区土壤母质来源和沉积环境的差异.不同地带土壤概率累积曲线的空间变化及综合参数特征表现出地形和气候对颗粒运动形式有一定影响,并且不同地区土壤在成因上既有区别又有联系.     

我国湖泊环境演变及其成因机制研究现状

湖泊沉积忠实地记录了湖泊环境变化的各类信息.不同时问尺度的湖泊环境变化分别受到构造、气候与人类活动三个方面的驱动机制的影响.影响中同湖泊环境变化的最主要的构造运动是青藏高原的隆升;气候变化的影响主要是东亚季风系统带来的一系列作用;而人类活动的影响则比较复杂,不仅有流域植被、土壤性质的改变导致输入湖泊物质的变化,也有人类活动直接改造湖泊,如围垦、封堵等.准确地分析湖泊环境变化的各种过程与规律,特别是定量刻画人与自然相互作用下的湖泊环境响应过程与驱动机理,是当今科学界的热点.     

兰州新一代天气雷达数据误差来源分析

新一代天气雷达目前已经成为对兰州市及周边地区短时强烈天气进行监测的主要手段之一。为了方便资料的处理和分析,提高观测资料准确度,为预报员和科研人员分析资料提供方便,通过对雷达数据前端生成和后端处理传输2个过程的分析,找出兰州新一代多普勒天气雷达数据误差的来源,并进行分析,发现地物回波、雷达天线增益、测量距离等因素和数据插值、坐标转换、远距离多终端传输等因素分别是前端数据产生过程中和后端数据处理传输过程中数据误差的主要来源。     

Nature and Evolution of Pre-Neoproterozoic Continental Crust in South China: A Review and Tectonic Implications

South China as an amalgamation of the Yangtze and Cathaysia blocks is composed of Archean to Mesoproterozoic basement overlain by Neoproterozoic and younger cover. Both the constituent Yangtze and Cathaysia blocks contain well-preserved Neoproterozoic rocks that have been extensively studied in terms of the age and tectonic nature, but less is known about their earlier crustal history due to the incomplete rock record. Recent efforts in investigating the yet survived crustal nature based on isotopic and elemental signatures preserved in igneous and sedimentary rocks have steadily improved our knowledge about the pre-Neoproterozoic continental crustal evolution in South China. In this paper, we summarize the up-to-date pre-Neoproterozoic records, including petrological, geochronological, geochemical and geophysical data, across South China, and discuss its spatiotemporal patterns of the pre-Neoproterozoic crust and the relevant tectonic events. While the xenocrystic/inherited and detrital zircon records suggest widespread Archean (mainly ca. 2.5 Ga) crustal components within both the Yangtze and Cathaysia blocks, exposed Archean rocks are only limited to isolated crustal provinces in the Yangtze Block. These Archean rocks are dominated by TTGs (tonalite-trondhjemite-granodiorite) with varied ages (3.3–2.5 Ga) and zircon Hf isotopes, indicating a compositionally heterogeneous nature of the Archean Yangtze Block and, by inference, the development of multiple ancient terranes. The early Paleoproterozoic (2.4–2.2 Ga) tectonomagmatic events characterize the western Yangtze Block and are supportive of an east-west subdivision of the Yangtze basement, whereas the late Paleoproterozoic (2.1–1.7 Ga) orogeneses may have affected a larger area covering both the western and eastern parts of the Yangtze Block, and also the Cathaysia Block. The eastern Yangtze Block with generally northeastward-younging late Paleoproterozoic magmatism and metamorphism likely experienced a prolonged 2.05–1.75 Ga orogenic process welding the various Archean proto-continents, consistent with the documentation of a buried late Paleoproterozoic orogenic belt imaged by deep seismic profiling from its central part and of a slightly older ophiolitic mélange in the northern part. The Cathaysia Block was probably involved in a short-lived 1.9–1.8 Ga orogenic event. The two orogeneses overlapped in time and may have contributed to the cratonization of a possible unified South China, and are referred to be linked with the assembly of the Nuna Supercontinent. The subsequent late Paleoproterozoic to early Mesoproterozoic rift successions and intrusions (1.7–1.5 Ga) in the southwestern Yangtze Block, and the ca. 1.43 Ga rifting in Hainan Island of the Cathaysia Block could be responses to the Nuna break-up. Late Mesoproterozoic (1.2–1.0 Ga) magmatism of varied age and nature in different localities of the Yangtze Block is reflective of a complex tectonic process in the context of the assembly of the Rodinia Supercontinent. Similar-aged metamorphism (1.3–1.0 Ga) is recorded in Hainan Island, reflecting the Grenvillian continental collision during the Rodinia assembly, but further studies are necessary to better constrain the late Mesoproterozoic tectonic framework of South China.     

我国产区的几种海水和淡水贝壳珍珠层粉成分的初步对比研究

为了系统研究和比较我国产区的一些海水和淡水贝壳珍珠层的物相和元素成分,我们采集了2种淡水育珠三角帆蚌壳和8种海水贝壳,其中4种是海水育珠马氏珠母贝壳,另4种是其它海水贝壳,并进行预处理以制备其贝壳珍珠层。然后使用X射线衍射、氨基酸分析、原子吸收光谱、原子荧光光谱法对贝壳珍珠层进行分析。结果表明这10种贝壳珍珠层的矿物物相都十分简单,主要由文石组成,仅含少量的方解石,并且它们的物相成分无明显的差别,难以通过X射线衍射（XRD）分析技术加以鉴定。与其它4种海水贝壳珍珠层相比,马氏珠母贝和三角帆蚌壳珍珠层的氨基酸含量明显大些。各种贝壳珍珠层的微量元素Na、Pb、Hg、As、Cu、Se、Cr、Mn的含量,与其品种基本无关,但可能与其生长的水环境有关。     

黔南坳陷下寒武统烃源岩地球化学特征及成因

为明确黔南坳陷下寒武统烃源岩地球化学特征及成因,采用岩石热解、GC、GC-MS等方法对3个典型剖面样品进行了系统分析。结果表明:黔南坳陷下寒武统黑色岩系为一套区域性海相优质烃源岩,厚约50~150 m;烃源岩TOC值为0.13%～15.40%,平均3.31%(n=169);烃源岩干酪根δ13C值为-35.79‰～-29.88‰,平均-32.85‰(n=35),显微组分主要为腐泥组;烃源岩干酪根海相镜质体反射率值为1.95%～3.96%,其等效镜质体反射率值为2.02%～3.47%;烃源岩饱和烃正构烷烃分布多为单峰形,主峰碳多为C22,C30藿烷和C27规则甾烷含量高,规则甾烷多为C27>C29>C28,Pr/Ph值为0.27～0.62,具较高的伽马蜡烷和硫芴含量,OEP值为0.82~1.11,C31升藿烷22S/(22S+22R)值为0.56~0.63,平均0.59;烃源岩总体具有富集轻稀土元素,Ba、Mo、V、U等元素含量高,具较强Ce负异常、Eu正异常和较高U/Th值等特征。总之,黔南坳陷下寒武统海相烃源岩分布广,厚度较大,有机质丰度高,类型好,热演化程度高,是高古生产力和缺氧环境共同作用的产物,可为黔南坳陷油气生成提供雄厚的成烃物质。