蒙甘青地区早白垩世原型盆地特征及其对烃源岩分布的控制

岩相古地理图可以大体反映盆地形成时的盆山格局和原始沉积特征。蒙甘青地区早白垩世岩相古地理图揭示了研究区在早白垩世发育了众多大小不一的沉积盆地群。由于早白垩世研究区处于伸展构造环境，这些盆地群构造性质多为拉张断陷盆地,普遍接受了下白垩统湖相—河流相沉积。早白垩世的沉积环境及岩相古地理条件有利于油气的形成，烃源岩主要分布在北祁连—阿拉善裂谷断陷盆地群中的次一级断陷中。烃源岩岩性为一套湖相的深灰色、灰黑色含钙质泥岩，明显受（浅湖—半深湖—深）湖相沉积体系的控制。此外，该区烃源岩的分布还受早白垩世“南干北湿”的气候带所控制。

CHARACTERISTICS OF EARLY CRETACEOUS PROTOTYPE BASIN AND ITS CONTROL ON SOURCE ROCK IN MONGOLIA-GANSU-QINGHAI AREA

The lithofacies palaeogeography map can show the pattern of basins and mountains and the characteristics of original deposition. The map of Mongolia-Gansu-Qinghai area revealed lots of different sizes sedimentary basin groups formed in early Cretaceous in study area. These basins often belonged to extension rift basin, received lacustrine-fluvial deposition of Lower Cretaceous due to extensional tectonics movement of early Cretaceous. The sedimentary environments and situation of lithofacies palaeogeography of early Cretaceous are favorable for hydrocarbon. The source rocks were mainly distributed in sub-depression of Northern Qilian-Alashan fault depression Group. The source rock is a set of grey and grey to dark calcareous mudstones of lacustrine, which were controlled by lacustrine depositional system (shallow-moderate-deep lake). Besides, the distribution of source rocks were dominated by the climate belts, dry in south and moist in north'.