Coal forming environments and their relationship to tectonic activity in the Cévennes Stephanian coal basin

Coal forming environments in the tectonically controlled intermontane Stephanian Cévennes coal basin (Massif central, France) show a complex interelationship between structural and sedimentological features. The study of the general structural features and the geometry of the coal beds developed during the different stages in the evolution of the basin, and the spatial relation of the lithofacial units to the early tectonic activities, lead the authors to suggest the following model. The synsedimentary faults that occurred as both intrabasinal and marginal faults controlled not only the spatial distribution, shape and thickness of the detrital rock units and coal seams, but also caused the inversion of the tectonic style. The marginal faults exercised important controls on the geometry of the basin and the distribution of lithofacial units. However due to the subsidence of the central part of the basin and the depocenter, and the to differences in the timing and intensity of the displacement the coal enrichment zones shifted both vertically and laterally. This eventually resulted in the inversion of the whole tectonic framework from semi graben through graben to a new semi graben. The style and rate of the tectonic movement and basin filling that occurred in the Stephanian Cévennes coal basin were in turn closely linked with the tectonic movement in the surrounding area. Therefore the authors propose that the environment and processes of coal formation in this basin are closely linked to its tectonic evolution.

Cevennes盆地北坳陷区独特的沉积与构造演化的耦合关系

发育于法国Cevennes聚煤盆地北坳陷区斯蒂芬期 (Stephanian)同沉积断层在空间上局部控制了碎屑体及煤层的形态、厚度 ,且在时间上完成了构造反转。盆缘断层控制了盆地自身的几何形态及其岩相古地理格局 ,它们的活动性及强度的差异致使盆地沉降或沉积中心、富煤带的侧向迁移 ,使盆地整体的构造格架发生了由半地堑 地堑 新型式的半地堑的转化。在不同的演化时期 ,盆地独特的沉积、充填作用对构造的活动与演化给予了积极的响应 ,体现了两者间清楚的耦合关系。盆地的充填与构造的活动方式及强度又与盆地周围古构造应力场在斯蒂芬期所发生的变化息息相关。

中国斯蒂芬期植物群的基本特征

重新定义后的中国斯蒂芬期植物群所对应的岩石地层单元只限于太原组下部晋祠段。该植物群以石松纲、楔叶纲、真蕨纲和种子蕨纲为主，也有一定数量的瓢叶纲和科达纲植物分子。尽管中国斯蒂芬期植物群与欧美同期植物群有一定共性，但二者差别仍很明显。

同沉积构造及其演化背景分析——以塞文煤盆地为例

同沉积构造在法国塞文煤盆地表现为盆内断层、盆缘断层及褶曲变形,发育在盆内斯蒂芬期含煤岩系中的几个主要同沉积正(逆)断层不但在空间上局部控制了碎屑体和厚煤层的分布形态、厚度大小,而且在时间上完成了正(逆)构造反转,盆缘断层控制了盆地自身的几何形态及其岩相古地理分布的格局,它们活动的先后及强度的差异导致盆地沉降中心或沉积中心和富煤带的侧向迁移,使盆地整体的构造格架发生了由半地堑→地堑→新型式的半地堑的转化,在不同的演化时期,盆内盆缘断层活动方式的改变或活动强度的变化对盆地周围古构造应力场在斯蒂芬期所发生的90°的旋转给予了积极的响应。

中国斯蒂芬期植物群的植物地理区系性质

以晋祠段为代表的中国斯蒂芬期植物群与欧美同期植物群有许多相同分子，但其中地方性植物分子比重较大，应属早期华夏植物群的一部分．该植物群与以太原组中上部为代表的Ｎｅｕｒｏｐｔｅｒｉｓｐｓｅｕｄｏｖａｔａ－Ｌｅｐｉｄｏｄｅｎｄｒｏｎｐｏｓｔｈｕｍｉｉ组合也存在一定差别，表现在典型的华夏植物群的重要成员尚未出现．

塞文煤盆地煤化作用研究

本文以煤的挥发分百分含量为指标对法国斯蒂芬期塞文煤盆地的煤化作用和古地温进行了研究,综合考虑和比较等挥发分线与盆地基底表面、煤层和上覆中生代地层的几何形态之间的关系,可定性地识别对煤化作用起主导控制作用的3个基本条件:(1)基底的起伏性;(2)中生代地层的巨厚覆盖;(3)断裂作用。定量计算所得到的古地温梯度表明该盆地为一“热”盆地,结合盆地的沉积充填史和构造演化史,提出了多期煤化作用的演化模式。