Chinese Continental Blocks in Global Paleocontinental Reconstruction during Paleozoic and Mesozoic

The Cambrian to Cretaceous paleomagnetic data from Chinese continental and adjacent blocks were collected using principles to obtain reliable and high-precision paleomagnetic data and to pay attention to the similarity of paleobiogeography and the coordination of tectonic evolution. The Chinese continental blocks were laid up on the reconstruction of proposed global paleocontinents with almost the same scale. Thus, it can be clearly recognized that the global continents, including Chinese continental blocks, range along latitudes on the southern side of the equator during the Early Paleozoic. In the Paleozoic, Chinese continental blocks were still located among the Laurentia, Siberia and Gondwana plates, following the fast moving of the Siberia Plate northwards, the amalgamation in a north-south direction at the western parts of the Laurentia and Gondwana plates, and the Iapetus and Rheic Oceans were subducted, eventually to form a uniform Pangea in the Late Paleozoic. The Australian and Indian plates of Eastern Gondwana moved and dispersed gradually southwards, continued to extend the Paleo-Tethys Ocean. The Chinese continental and adjacent blocks were still located in the Paleo-Tethys Ocean, preserved the status of dispersion, gradually moving northwards, showing characteristics of ranging along a north–south orientation until the Permian. In addition, a series of local collisions happened during the Triassic, and consequently most of the Chinese continental blocks were amalgamated into the Pangea, except for the Gangdise and Himalayan blocks. There was a counter-clockwise rotation of the Eastern Asian continent in the Jurassic and northwards migration of the Chinese continent in varying degrees during the Cretaceous, but the Himalayan and Indian plates did not collide into the Chinese continent during this period.     

大火成岩省及其在古大陆重建及裂解研究中的应用

大火成岩省是地质历史上与地球深部过程（如地幔柱）密切相关的极端地质事件,以相对较短时期内形成规模宏大的板内幔源基性岩浆活动为主要特征,对研究全球性大气—海洋环境的巨变与生物灭绝、大规模成矿及超大陆的重建和裂解均有重要意义。从潘吉亚超大陆的裂解过程可以看出,尽管不是所有的大火成岩省都与大陆裂解有关,但几乎每一次重要的裂解事件都伴有大火成岩省的出现,因此大火成岩省对于研究前潘吉亚超大陆,特别是对于缺少古生物等重建标志,古地磁数据偏少的前寒武纪超大陆重建及裂解研究有重要价值。近20多年来随着年代学技术的进步及研究工作的不断深入,大火成岩省在古大陆重建及裂解方面取得了一些重要进展,并发挥了越来越重要的作用。前寒武纪大火成岩省由于经历了多次裂解事件改造及后期抬升剥蚀或覆盖的影响,现今保留的是一些分散在不同大陆上的大火成岩省残片或碎片。用大火成岩省开展古大陆重建及裂解的目标就是通过不同陆块大火成岩省或大规模基性岩浆活动的年代学、岩石学及地球化学对比,结合其他证据,恢复大火成岩省形成时的时空分布特征,据此来确定这些陆块在超大陆中的相对或绝对位置。与其他前寒武纪大陆重建标志相似,大火成岩省也有一些局限性及不确定性,因此应用大火成岩省开展古大陆重建及裂解研究中要与前岩浆期沉积地层中的特殊事件层（如冰碛岩、火山灰、黑色页岩、不整合面、古生物等）对比、岩墙几何学产状、基性岩浆事件序列对比、古地磁、大型构造（如造山带）对比及深部地球物理等多学科方法相结合。     

华北克拉通北缘凉城基性岩墙成因及古地理的重建意义

为揭示华北克拉通北缘凉城基性岩墙的形成时代、岩石成因、构造背景及对罗迪尼亚超大陆重建的意义,本研究借助激光烧蚀多接收器等离子质谱(LA-MC-ICP-MS)锆石U-Pb定年、Hf同位素及全岩地球化学研究手段,对凉城桃花沟岩墙开展了系统研究。研究结果显示,凉城桃花沟岩墙为新元古代早期(903±15 Ma)基性岩浆活动的产物,归属拉斑岩石系列,具有较高的TFeO(12.78%～16.30%)及TiO₂(2.59%～3.31%)含量、较低的MgO(2.87%～3.83%)、Cr(32.7×10^-6～42.0×10^-6)、Ni(11.6×10^-6～14.5×10^-6)含量及Mg^#值(29～38),富集轻稀土元素(LREE)、Rb、Pb、Zr及Hf元素,亏损Ba、Sr、Nb、Ta、Ti及Eu(Eu/Eu^*=0.74～0.83)元素。锆石原位ε_Hf(t)范围为2.4～13.4,单阶段Hf模式年龄(t_DM1     

汉南—川东北灯影组古地理演化:晚震旦世扬子西北缘拉张背景的沉积学证据

古地理面貌的呈现往往是构造演化与沉积充填共同作用的结果。通过对野外露头系统的观察与分析,在汉南—川东北地区进行了晚震旦世灯影期沉积相分析,识别出古隆起、局限台地、开阔台地和台缘斜坡4种类型的古地理单元;确定了汉南—川东北地区地势南高北低、各沉积单元呈南北向和北东向展布,且在平面上呈现"一隆两凹"的古地理面貌特征。在露头及盆地内钻井岩芯识别出的同沉积断层等特征,反映了沉积区处于拉张构造背景;且古地理研究中所确定的沉积坳陷区与隆起区的位置与重磁震等地球物理资料中识别出的裂陷/坳陷和古隆起位置相吻合,证实了四川盆地内绵竹—乐至—隆昌—长宁拉张槽/裂陷槽和万源—达州裂陷槽的存在,表明灯影期汉南—川东北地区处于拉张的构造背景,反映古地理背景发生了由稳定沉积到活动拉张的变化,并且经历了稳定沉积、拉张前奏和主体拉张三个阶段,进一步印证了沉积演化与构造背景之间的耦合关系。     

吐哈盆地西山窑组第二段岩相古地理和聚煤作用

吐哈盆地烃源岩主要是早朱罗世八弯组和中侏罗世西山窑组的煤和碳质泥岩。本文对该盆地主要含煤段－西山窑组第二段沉积期岩相古地理进行了分析，编制了各种图件，总结出该期岩相古地理特征并分析了聚煤作用的控制因素。     

滇中（楚雄）晚三叠世盆地成因机制、聚煤古地理类型与找煤方向

滇中盆地是在长期隆起的川滇古陆核（习称康滇古陆）于印支晚期经剧烈沉降形成的中、新生代沉积盆地。其中的晚三叠世含煤岩系是滇中与川西南重要含煤层位。通过对该区历年煤炭资源地勘资料、区域地质调查与科研成果的综合分析,在盆地成因、古构造活动与后期改造及聚煤古地理类型方面形成了新的认识,提出了在原大、中型煤矿区外围深部有利地带寻找隐伏煤田的具体意见,企盼滇中盆地的找煤工作有新的突破。     

中国生物礁时空分布特征及其地质意义

中国生物礁从震旦纪至新近纪均有发育，分布范围广，并有泥盆纪、二叠纪和新近纪3个主要造礁期。不同地史时期造礁生物及其附礁生物的组合不同，形成的礁体具有不同的类型、规模和特征。生物礁的发育受构造作用、海平面变化及古地理环境控制，同时也受遣礁生物兴衰演化的控制。生物礁与油气藏、金属矿床空间上关系密切，成因上可有联系。笔者系统总结了20多年来中国生物礁的研究进展和成果，并指出利用多学科综合方法能较成功地预测隐伏生物礁的发育和分布，寻找礁型油气藏和礁型矿床。     

Tectonic Evolution and Key Geological Issues of the Proto‐South China Sea

There are numerous controversies surrounding the tectonic properties and evolution of the Proto-South China Sea(PSCS).By combining data from previously published works with our geological and paleontological observations of the South China Sea(SCS),we propose that the PSCS should be analyzed within two separate contexts:its paleogeographic location and the history of its oceanic crust.With respect to its paleogeographic location,the tectonic properties of the PSCS vary widely from the Triassic to the mid-Late Cretaceous.In the Triassic,the Paleo-Tethys and the Paleo-Pacific Oceans were the major causes of tectonic changes in the SCS,while the PCSC may have been a remnant sea residing upon Tethys or Paleo-Pacific oceanic crust.In the Jurassic,the Meso-Tethys and the Paleo-Pacific oceans joined,creating a PSCS back-arc basin consisting of Meso-Tethys and/or Paleo-Pacific oceanic crust.From the Early Cretaceous to the midLate Cretaceous,the Paleo-Pacific Ocean was the main tectonic body affecting the SCS;the PSCS may have been a marginal sea or a back-arc basin with Paleo-Pacific oceanic crust.With respect to its oceanic crust,due to the subduction and retreat of the Paleo-Pacific plate in Southeast Asia at the end of the Late Cretaceous,the SCS probably produced new oceanic crust,which allowed the PSCS to formally emerge.At this time,the PSCS was most likely a combination of a new marginal sea and a remnant sea;its oceanic crust,which eventually subducted and became extinct,consisted of both new oceanic crust and remnant oceanic crust from the Paleo-Pacific Ocean.In the present day,the remnant PSCS oceanic crust is located in the southwestern Nansha Trough.     

Tectonic implications of Late Paleozoic stratigraphic distribution in Northeast China and adjacent region

An analysis of the distribution of the Late Paleozoic strata on Northeast China and adjacent region reveals a zonal pattern of the distribution around the core of the Jiamusi-Mongolia Block. The main part of Late Paleozoic marine strata in this area is considered the continental margin deposits of the Jiamusi-Mongolia Block by analyzing the stratigraphic contact relationship, lithofacies, etc. The results are exhibited in a series of tectonic paleogeographic maps. This presents an important proof for the foundation of the Jiamusi-Mongolia Block, and confines the forming time of Jiamusi-Mongolia Block to the Late Silurian. Supported by Science and Technology Project of Sinopec (Grant No. G0800-06-ZS-324)