柴达木盆地西部地区第三系碎屑岩粒度概率累积曲线特征

Probability cumulative grain size curves in terrigenous of the Tertiary in west Qaidam Basin

在岩心观察的基础上,利用主要取心井的粒度分析资料,对柴达木盆地西部地区第三系碎屑岩主要沉积环境的粒度概率曲线进行了研究。研究表明,该地区发育的沉积相有扇三角洲、冲积平原、三角洲、湖泊、湖底扇,每一种沉积相又分为几种沉积亚相类型;该地区碎屑岩的粒度概率累积曲线特征主要包括:“上拱弧形”式、一段式、两段式、三段式、多段式、复杂两段式和复杂三段式、“低斜多段”式、“高斜多跳一悬”式和“高斜多跳一悬夹过渡”式、“高斜多跳”式、“宽缓上拱”式等,每种沉积亚相类型对应其独特的粒度概率累积曲线特征。该研究成果可为新探区的沉积环境判断提供参考。

Base on observation of cores and analyzing data of grain size, the probability cumulative grain size curves in the main sedimentary environments of the Tertiary in west Qaidam Basin were summarized. The researches show that fan delta, alluvial plain, delta, lacus and sublacustrine fan develop, each sedimentary facies are divided into several subfacis again. The probability cumulative grain size curves incude “uphill arched arc” pattern, one segment attern, bi-segment pattern, tri-segments pattern, multi-segments pattern, complicated hi-segment pattern, complicated tri-segments pattern, “low slope multi-segments” pattern, “high slope muhi-bouncing population-one suspension population” pattern,“high slope multi-bouncing population-one suspension population-transitional zone” pattern,“high slope and multi-bouncing population” pattern, “broadly uphill arched arc” pattern and so on, each subfacis has own peculiar probability cumulative grain size curves. This research can provide reference for judgement of new prospect＇s sedimentary environment.