塔里木盆地第三系伊利石结晶度纵向变化的地质意义

塔里木盆地第三系处于早成岩阶段, 泥岩中的伊利石结晶度至今仍保持着盆地周围造山带近变质物源的结构特征。伊利石的结晶度由下向上变好, 纵向上变化的两个明显台阶正好与喜马拉雅造山运动抬升的第Ⅰ 、Ⅱ幕时期相一致, 反映了造山带不断抬升剥蚀的快速沉积特征。研究认为,快速抬升、剥蚀、堆积和低的成岩程度是近变质伊利石的结构特征能够保存的两个必要条件, 也是决定泥岩粘土矿物组成特征的最主要因素。

GEOLOGIC SIGNIFICANCE OF ILLITE CRYSTALLINITY IN TERTIARY MUDSTONE, TARIM BASIN

The Tertiary in Tarim basin is in the early diagenesis stage. The illite crystallinity in Tertiary mudstone remains the same as the anchi metamorphic source rock in orogenic belt in the periphery, and becomes better from bottom to top. The vertical illite crystallinity variation remarkably divides into two stages, just consistent with the first and second episodes during the elevation stage of Himalayan movement, which reflects the rapid sedimentary characteristics of continuous uplift and denudation of orogenic belt. It is believed that rapid uplifting, denudation, accumulation, and low diagenetic degree are necessary to allow the structural features of anchi metamorphic illites preserved, and also the most important control on the compositional characteristics of clay mineral in mudstone.