渤海湾西岸QG01钻孔沉积物黏土矿物分布及古气候替代指标研究

The studyof claymineral assemblages and paleoclimatic proxies of borehole QG01 in the western coast of Bohai Bay,China

对渤海湾西岸QG01钻孔12.7～17.4m段沉积物进行了粒度测试、X射线衍射(XRD)和光释光(OSL)测年,分析了该段岩心的黏土矿物特征及其对古气候的响应。该段沉积物由砂质粉砂、粉砂质砂和黏土质粉砂组成,平均粒径介于4.11～7.79Φ之间;黏土矿物以伊利石为主,其次为绿泥石和高岭石,蒙脱石含量最少。将伊利石结晶度(KI)和黏土矿物组合比值((伊利石+绿泥石)/(高岭石+蒙脱石))作为古气候替代指标,发现当KI与黏土矿物组合比值反映的气候变化趋势一致时,可反映气候变化特征;当KI与黏土矿物组合比值反映的气候变化趋势不一致时,沉积物来源发生改变,不能反映气候特征。

The sediments from 12.7m to 17.4m in the core QG01which was taken from the west coast of Bohai Bay were analyzed with grain size analysis,XRD and OSL,the characteristics of clay mineral assemblages and used as paleoclimatic proxies were also investigated.The sediments are composed of sandy silt,siIty sand,and clayey silt,with the rage 4.11--7.79Ф.The results show that illite-chlorite-kaolinite- smectite is the main clay mineraI assemblage.The KI and the ratio values of "(illite+chlorite)/(kaoliniteq- smectite)"are used as paleoclimate proxies.The results show that two proxies can reflect the feature of climate change when the trends of the two proxies are corresponding.On the contrary,when the trends of the two proxies do not correspond with each other,they cannot be used as paleoclimatic proxies since the source of sediments may change.