渤海湾西岸BQ1孔揭示的沉积环境与海面波动

Sedimentary environment and sea-level fluctuations revealed by Borehole BQ1 on the west coast of the Bohai Bay, China. Geological Bulletin of China,

渤海湾西岸BQ1孔位于歧口凹陷区内,孔深95.6m,揭露了晚更新世以来比较连续的沉积。通过对109个样品鉴定和环境分析,共分辨出Ⅱ、Ⅱ、Ⅲ三个海相层及其内部的海面波动。每个海相层内均有前后2次海侵高峰和中间的海退。在全新世海侵层中共区分出9次海面波动,分辨率达500～800a级；第Ⅲ海相层存在5次海面波动,与深海O同位素的5a、5c、5e分期的峰值大体对应。在海相层中,海陆过渡相层位占较大比例,其中的石膏结晶和黄铁矿晶簇是该相的重要指相矿物。所见的Ⅰ、Ⅱ、Ⅲ海相层皆为平均海平面下数米的浅海沉积。

The BQ1 core （95.6 m）, located in the Qikou tectonic subbasin on the west coast of the Bohai Bay, has revealed relatively continuous sediments since the late Pleistocene. Through identification of 109 samples and analysis of the sedimentary environment, three marine beds （ Ⅰ、Ⅱ and Ⅲ ） and their internal sea-level fluctuations are distinguished. Each rnarine bed contains peaks of two transgressions and one regression between the two transgressions. Nine sea-level fluctuations are further distinguished in the Holocene marine beds with a resolution of 500-800 years. In marine bed Ⅲ there are five sealevel fluctuations, which largely correspond to the peaks of deep-sea oxygen isotope stages 5a, 5c and 5e. The transitional facies sequences have a large proportion in all marine beds, in which gypsum and pyrite are important diagnostic minerals of the facies. All of the observed marine beds are intertidal and shallow-water sediments.