胶莱盆地胶州组生物地层及白垩系/古近系界线

胶莱盆地是我国东部典型的陆相中生代断陷盆地,盆地内王氏群胶州组为一套河湖相沉积,为跨晚白垩世和古新世的岩石地层单元.为确定胶莱盆地的白垩系/古近系(K/Pg)界线位置,笔者对胶州市的胶州组露头剖面进行测量,并实施了科学钻探JZK01孔和JZK02孔.对露头和钻孔剖面进行系统取样,在胶州组下部发现 Turbochara specialis-Collichara taizhouensis-Hornichara prolixa-Raskyaechara gobica轮藻组合、Talicypridea reticulata-Cypridea cavernosa-Mongolocypris distributa-Ziziphocypris simakovi介形类组合,以及3个孢粉组合:Ulmoideipites-Ulmipollenites minor-Aquilapollenites minor孢粉组合、Deltoidospora-Schizaeoisporites孢粉组合和Callistopollenites-Quercoidites-榆科孢粉组合.在胶州组上部发现Peckichara varians-Grovesichara changzhuensis-Chara yuntaishanensis轮藻组合和Porpocypris sphaeroidalis-Sinocypris cf.funingensis-Mongolocypris longa介形类组合.胶州组下部和上部层位的时代分别被确定为晚白垩世马斯特里赫特期和古新世早、中期,并将JZK02孔的K/Pg界线确定在40.95-73 m之间,JZK01孔确定在9.7-35.55 m之间.