摘要:
造山带古地理的恢复与重建难度较大且尚无研究方法体系可循。选择地处复杂中央造山带的甘肃省奥陶纪为例,结合前人研究资料首次编制了早、中晚奥陶世的沉积构造格架及沉积盆地类型图,分析了它们之间的空间配置关系。在“构造控盆、盆控相”的思路控制下,以沉积岩性、结构—构造、古生物组合等为基础,以优势相原则,共划分出滨浅海相、浅海陆棚相、开阔台地相、台地边缘浅滩相、潮坪相以及半深海(含斜坡相)—深海相等7类沉积相类型,采用“在同一板块、构造背景下形成的沉积盆地内及空间连续配置的沉积盆地之间采用瓦尔特相律对古地理进行合理的恢复;对不同的板块及构造背景下形成的沉积盆地或者是空间不连续配置的沉积盆地之间,古地理单元的恢复则按现今出露地层所反应出的沉积环境忠实地表现,古地理单元之间可以不遵循瓦尔特相律”的方法恢复与重建了研究区的古地理面貌,编制了相应的古地理图。为造山带岩相古地理的研究提供了一种编图思路,具理论和实践意义。
Abstract:
It's difficult to restore and reconstruct the palaeogeographic of the orogenic belt, and there was no research method system to follow. Ordovician in Gansu province was the study target. Combined with the existing study, compiled the sedimentary tectonic map and the sedimentary basin type map of the Lower-Middle-Late Ordovician, the relationship of spatial disposition between them was analyzed. Under the "basin-controlling tectonic, facies-controlling basin" thought, on the basis of the sedimentary lithology, texture-structure and the paleontological, and using the dominant facies principle, littoral-neritic facies, shelf facies, open sea platform facies, platform margin shoals facies, tidal flat facies, bathyal facies (including slope facies) and abyssal facies were figured outin study area. "In the same plate and the same tectonic settings, or in the sedimentary basin which have the space connection configuration, the Walther facies law was used to restore the paleogeographic of the basin. However, restoring paleogeographic of the basin by the real sedimentary environment of the emergence stratums, Palaeogeographic units can't follow the Walther facies law." Under the guidance of the principle, Paleogeography of the study area was restored and rebuilt, also, the corresponding paleogeographic map was established. It provides a mapping train of restoring lithofacies-paleogeographic for orogenic belt, which has the theoretical and practical significance.
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