节点文献
贵州峨眉山玄武岩喷发期的岩相古地理研究
STUDY ON LITHOFACIES PALAEOGEOGRAPHY DURING THE PERMIAN EMEISHAN BASALT EXPLOSION IN GUIZHOU PROVINCE
【摘要】 贵州峨眉山玄武岩喷发 ,从动态的角度可以分为茅口期晚期和龙潭期 (吴家坪期 ) ,龙潭期又可分为三个喷发旋回 ,对应于四个不同的岩相古地理环境 ,体现了东吴运动在造成贵州地区地壳抬升、下沉和接受最大海侵之后 ,又上升、拉张、沉陷带发生地裂 (又称峨眉地裂 )以及地幔物质喷溢等地质活动 ,具间歇性和多旋回性的特点。本文从研究海陆变迁入手 ,揭示峨眉山玄武岩喷发与沉积作用的内在联系 ,进而探讨其与金、锑等矿产的成因联系 ,提出该期各相区与成矿区的形成模式。通过对贵州峨眉山玄武岩不同喷发期岩相古地理的研究可以看出 ,茅口期晚期和龙潭期早期海域的沉积韵律和相带展布格局与玄武岩喷发的间歇性和多旋回性特征完全一致。玄武岩的喷发为成矿提供了物质基础 ,玄武岩喷发的间歇期又为沉积矿产的富集提供了机遇。这种岩浆期后气液以富硅和二氧化碳为特征的玄武岩 ,本身富含铁、锰、铜、铅、锌、锑、砷、汞、金、银、氟、磷以及一些稀散和放射性元素等成矿组分。在喷发过程中 ,气液成分有一定变化 ,各阶段和离岩浆的远近距离不同以及喷发性质和环境差异 ,形成了火山气液矿床、火山沉积矿床和沉积矿床的不同成矿带。
【Abstract】 Explosion phases of the Emeishan basalt in Guizhou Province of China, can be divided into late Maokou phase and Longtan phase (or Wujiaping phase) according to the intensity and time of explosion. The Longtan phase may be subdivided into 3 explosion cycles corresponding to 4 different environments of lithofacies palaeogeography. It is shown that the Dongwu Movement caused elevation and subsidence of the earth crust and accepted regression and transgression, then following elevating, spreading and cracking (or called as Emeishan cracking), and of exploiting mantle material with the discontinuous and multicycled features. The interrelationship between process of the Emeishan basalt explosion and the sedimentation process is revealed on the study of evolution of palaeogeography in Permian. The relationships between genesis of gold and stibium deposits and the Emeishan basalt explosion as well as the evolution of palaeogeography are discussed. The relationship models between lithofacies and minerogenetic province are set up. It can be seen that the sediment cycles and the distribution of lithofacies in Maokou Stage and Early Longtan Stage are consistent with the Emeishan basalt explosion episodes and cycles. The Emeishan basalt explosion supplied a lot of materials for forming the mineral resources. The intervals of the Emeishan basalt explosion were favorable to the accumulation of the abundant and different deposits. The basalt is rich in Si and CO 2 during the gas-hydrate interval of magma effusion process, and also rich in Fe, Mn, Cu, Pb, Zn, Sb, Hg, As, Au, Ag, F, P and the rare and radioactive elements. The distribution of mineral regions, such as volcano-gas-hydrate mineral region, volcano-sediment mineral region and sediment mineral region was controlled by the distances to the crater and magma, as well as the different volcano compositions mineral environments.
【Key words】 Lithofacies palaeogeography; Emeishan basalt; mineral genesis pattern; Guizhou Province;
- 【文献出处】 古地理学报 ,Journal of Palaeogeography , 编辑部邮箱 ,2003年01期
- 【分类号】P531
- 【被引频次】96
- 【下载频次】1079